Carbohydrate Term Paper :/
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CATindeeHAT
Posts: 332 Member
Hey all!
I'm in the middle of writing my midterm paper for my Integrative Human Systems Physiology Class and I seriously need to take a break. :noway:
The assignment is to write a 27-page paper explaining how over-consumption of dietary carbohydrates leads to weight-gain in the general population and it's mechanisms. I'm on page 18 and my head is starting to hurt so I figured I would take a break and share with you what I'm learning since some of you may be interested! :flowerforyou
I figured the best way to share my learning experience is to just simply share some of my sources. That way we can avoid any discrepancies concerning the 'accuracy' of my information. :huh:
So here you go!
Oh, and P.S. All of these articles were published in 2012.
Cheers! :drinker:
Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22673594
Talib A. Hussain, M.B., Ch.B., R.C.G.P.a, Thazhumpal C. Mathew, M.Sc., Ph.D., F.R.C.Path.b, Ali A. Dashti, M.Sc., Ph.D.b, Sami Asfar, M.B., Ch.B., M.D., F.R.C.S., F.A.C.S.c, Naji Al-Zaid, B.Sc., Ph.D.d, Hussein M. Dashti, M.D., Ph.D., F.I.C.S., F.A.C.S.c, ,
Abstract
Effective diabetic management requires reasonable weight control. Previous studies from our laboratory have shown the beneficial effects of a low-carbohydrate ketogenic diet (LCKD) in patients with type 2 diabetes after its long term administration. Furthermore, it favorably alters the cardiac risk factors even in hyperlipidemic obese subjects. These studies have indicated that, in addition to decreasing body weight and improving glycemia, LCKD can be effective in decreasing antidiabetic medication dosage. Similar to the LCKD, the conventional low-calorie, high nutritional value diet is also used for weight loss. The purpose of this study was to understand the beneficial effects of LCKD compared with the low-calorie diet (LCD) in improving glycemia.
Methods
Three hundred and sixty-three overweight and obese participants were recruited from the Al-Shaab Clinic for a 24-wk diet intervention trial; 102 of them had type 2 diabetes. The participants were advised to choose LCD or LDKD, depending on their preference. Body weight, body mass index, changes in waist circumference, blood glucose level, changes in hemoglobin and glycosylated hemoglobin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, urea and creatinine were determined before and at 4, 8, 12, 16, 20, and 24 wk after the administration of the LCD or LCKD. The initial dose of some antidiabetic medications was decreased to half and some were discontinued at the beginning of the dietary program in the LCKD group. Dietary counseling and further medication adjustment were done on a biweekly basis.
Results
The LCD and LCKD had beneficial effects on all the parameters examined. Interestingly, these changes were <b>more significant</b> in subjects who were on the LCKD as compared with those on the LCD. Changes in the level of creatinine were not statistically significant.
Conclusion
This study shows the beneficial effects of a ketogenic diet over the conventional LCD in obese diabetic subjects. The ketogenic diet appears to improve glycemic control. Therefore, diabetic patients on a ketogenic diet should be under strict medical supervision because the LCKD can significantly lower blood glucose levels.
Effect of a low-carbohydrate, ketogenic diet program compared to a low-fat diet on fasting lipoprotein subclasses
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/16297472
Eric C. Westmana, William S. Yancy Jr.a, b, Maren K. Olsenb, c, Tara Dudleyb, John R. Guytona
• a Department of Medicine, Duke University Medical Center, Durham, NC, USA
• b Center for Health Services Research in Primary Care, Department of Veterans' Affairs Medical Center, Durham, NC, USA
• c Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA
Abstract
Background
Low-carbohydrate, ketogenic diets (LCKD) are effective for weight loss, <b>but concerns remain regarding cardiovascular risk.</b> The purpose of this study was to determine the effect of an LCKD program on serum lipoprotein subclasses.
Methods
This was a randomized, two-arm clinical trial in an outpatient research clinic involving overweight, hyperlipidemic community volunteers motivated to lose weight. Subjects were randomized to either an LCKD (n = 59) and nutritional supplementation (including fish, borage and flaxseed oil), or a low-fat, reduced-calorie diet (LFD, n = 60). The main outcomes were fasting serum lipoprotein subclasses determined by nuclear magnetic resonance analysis.
Results
The mean age of subjects was 44.9 years, the mean BMI was 34.4 kg/m2, and 76% were women. Comparing baseline to 6 months, the LCKD group had significant changes in large VLDL (− 78%), medium VLDL (− 60%), small VLDL (− 57%), LDL particle size (+ 2%), large LDL (+ 54%), medium LDL (− 42%), small LDL (− 78%), HDL particle size (+ 5%), large HDL (+ 21%), and LDL particle concentration (− 11%). Compared with the LFD group, the LCKD group had greater reductions in medium VLDL (p = 0.01), small VLDL (p = 0.01) and medium LDL (p = 0.02), and greater increases in VLDL particle size (p = 0.01), large LDL (p = 0.004), and HDL particle size (p = 0.05).
Conclusions
The LCKD with nutritional supplementation led to beneficial changes in serum lipid subclasses during weight loss. <b>While the LCKD did not lower total LDL cholesterol, it did result in a shift from small, dense LDL to large, buoyant LDL, which could lower cardiovascular disease risk.</b>
Low-carbohydrate diet bested standard calorie restriction for lowering glucose levels, weight loss
SOURCE: http://www.healio.com/footer/account-information/login?returnUrl=/endocrinology/obesity/news/print/endocrine-today/{75887CF5-7B4B-4F01-9DEC-CC4C05F9A67E}/Low-carbohydrate-diet-bested-standard-calorie-restriction-for-lowering-glucose-levels-weight-loss
Foster, Melissa; Shafer, Emily. Endocrine Today 10. 1 (Jan 2012): 16.
Adhering to a strict, low-carbohydrate diet 2 days per week led to greater reductions in weight and insulin levels when compared with standard daily dieting.
Weight loss and reduced insulin levels are required for breast cancer prevention, but [these levels] are difficult to achieve and maintain with conventional dietary approaches," Michelle Harvie, PhD, registered dietitian at the Genesis Prevention Center at the University Hospital in South Manchester, England, said in a press release.
To investigate the efficacy and feasibility of two intermittent, low-carbohydrate diets, Harvie and colleagues randomly assigned 115 overweight or obese women at increased risk for breast cancer to three different diets for 4 months: a low-carbohydrate, restricted calorie diet for 2 days per week; an "ad lib" low-carbohydrate diet that included other foods such as protein for 2 days per week; and a standard daily restricted Mediterranean diet.
Patients in the standard diet group experienced 2.4-kg weight loss (95% CI, 1.2-3.4), researchers said. Patients in the restricted low-carbohydrate diet group lost 4.3 kg (95% CI, 3-5.6), and patients in the ad lib low-carbohydrate diet lost 4.1 kg (95% CI, 3.1-5.2), researchers said.
"It is interesting that the diet that only restricts carbohydrates, but allows proteins and fats, is as effective as the calorie- restricted, low-carbohydrate diet," Harvie said.
Additionally, patients in the intermittent, low-carbohydrate diet study arms demonstrated greater reductions in insulin resistance vs. those in the standard diet arm. Mean difference from baseline to study conclusion was 22% for patients in the restricted-calorie group and 14% in the ad lib group vs. 4% in the standard diet group, according to the data.
"Greater weight loss, fewer dropouts and greater reductions in insulin resistance with the novel intermittent and low-carbohydrate diets indicate that these are alternative approaches for energy restriction for potentially reducing risk for breast cancer and other diseases," the researchers concluded.
No changes in time trial performance of master endurance athletes after 4 weeks on a low carbohydrate diet
SOURCE: http://rd.springer.com/article/10.1007/s11332-012-0129-2
Maria Francesca Piacentini, Attilio Parisi, Nicole Verticchio, Stefania Comotto, Romain Meeusen and Laura Capranica
Abstract
The purpose of the present study was to evaluate the effects of a 4-week low-carbohydrate (CHO) diet regimen on body weight, exercise performance and hormonal response to running in master athletes. Six endurance master athletes performed three 30-min time trials, before (TT1), after 15 days (TT2) and after 30 days (TT3) on a low CHO diet. Blood samples were collected for hormonal and lactate measurements. After 15 days body weight had decreased (TT1 72.3 ± 2.4 kg, TT2 70.0 ± 2.7 kg; P = 0.006) and then remained stable. No differences were observed in performance (TT1 7,015 ± 273 m, TT2 6,920 ± 286 m, TT3 7,202 ± 315 m) and in the insulin/glucagon ratio. After 2 and 4 weeks, adrenocorticotropic hormone decreased significantly both at rest (baseline: TT1 42.5 ± 7.8 pg•ml−1, TT3 21.6 ± 3.2 pg•ml−1) and during exercise (end of exercise: TT1 120 ± 20 pg•ml−1, TT2 80 ± 16 pg•ml−1, TT3 31 ± 2 pg•ml−1). Baseline cortisol concentrations had increased significantly after as little as 15 days on the low CHO diet. The results of the present study demonstrate no changes in time trial performance in master endurance athletes after 4 weeks on a low CHO diet. However, an effect on the hypothalamic pituitary adrenal axis emerged.
Low-carbohydrate high-fat diets in combination with daily exercise in rats: effects on body weight regulation, body composition and exercise capacity
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22342194
by Caton, Samantha J; Obici, Silvana; Kienzle, Ellen; Tschöp, Matthias H; Bidlingmaier, Martin; Bielohuby, Maximilian (more...)
Abstract
The aim of the current investigation was to examine the effects of consuming a low-carbohydrate high-fat diet (LC-HFD) in combination with daily exercise on body weight, body composition, endocrine control of the energy balance system and exercise capacity in adolescent and mature rats. Adolescent (n=23) and mature rats (n=16) were maintained on either a standard chow diet (CH) or a LC-HFD for a period of ten days prior to daily exercise training for 21 days in forced running wheel system. At the end of the 21 day training sessions all rats took part in an exercise performance test where time to exhaustion was measured. Rats maintained on the LC-HFD demonstrated a significant lack of body weight gain (p<0.05) compared to CH maintained rats, despite equicaloric intake and performing identical amounts of daily exercise. Body composition was significantly altered in the LC-HFD rats (p<0.05) with increased body fat (p<0.01). Leptin concentrations were higher (p<0.05) and IGF-I concentrations were lower (p<0.01) in the LC-HFD fed rats. Exercise performance was not diminished in the LC-HFD group despite the higher fat mass. Both groups irrespective of age performed equally as well in the time to exhaustion test (p>0.05). Maintenance on the LC-HFD in combination with forced daily exercise did not impact exercise capacity (total distance and meters per minute). <b>Additionally consumption of an extreme LC-HFD in combination with daily exercise resulted in significantly less body weight gain but increased fat mass. When combined with daily exercise this diet clearly had a negative impact on body composition, but did not affect exercise capacity.</b>
Optimal Weight Loss Diet to Reduce Cardiovascular Risk
Source: Clinical Cardiology Alert. (Feb. 1, 2012):
Document Type: Clinical report
SOURCE: http://www.highbeam.com/doc/1G1-285208898.html
Abstract & Commentary
By Michael H. Crawford, MD, Editor
Source: Gogebakan O, et al.
Effects of weight loss and long-term maintenance with diets varying in protein and glycemic index on cardiovascular risk factors: The Diet, Obesity, and Genes (DiOGenes) study: A randomized controlled trial. Circulation 2011;124:2829-2838.
This pan-European multicultural study investigates whether after initial weight loss in overweight subjects, a subsequent diet of high or low carbohydrate (glycemic index) or protein diets helped subjects maintain their new weight better. Their initial results showed that the low glycemic, high-protein diet was superior for maintaining their weight for 26 weeks. The present study evaluated which diet best improved hsCRP, triglycerides, cholesterol levels, and blood pressure vs a control group in 932 overweight adults who lost weight on an 8-week low-calorie diet. Of the 773 randomized to one of the four diets, 71% completed the study. Average weight loss in the low-calorie period was 11 kg. Of the subsequent diets, only the low-protein high-glycemic diet resulted in weight regain (+ 1.7 kg). Weight loss reduced hsCRP, cholesterol (HDL and LDL), triglycerides, and blood pressure. During the maintenance phase, hsCRP was reduced further in the low-glycemic diets vs high and on low protein diets vs high. Cholesterol, triglycerides, and blood pressure were not differentially affected by the four diets. The authors conclude that after weight loss, a low glycemic index and, to a lesser extent, low-protein diet may reduce inflammation associated with cardiovascular disease in overweight adults.
Commentary
With two-thirds of American adults being either overweight or obese, scientific data on appropriate diets are important. The original trial report of this study showed that caloric restriction was necessary for weight loss and diet composition had little effect. The emphasis on low-fat diets to reduce cholesterol and reduce cardiovascular risk may be thwarted if subjects substitute carbohydrates for the fat calories, resulting in little or no weight loss. As this follow-up study shows, a high glycemic index diet may also blunt the decrease in low-grade inflammation associated with weight loss and increase cardiovascular risk. Maintaining a high-protein diet also can blunt the decrease in hsCRP following weight loss, but to a much lesser extent than a high-glycemic diet. However, high-protein diets are known to improve lipid profiles. What the balance between lower LDL cholesterol and higher inflammation will do to subsequent cardiovascular risk is not known, but since cholesterol can be lowered by other means, the lower inflammation on a low-glycemic diet could be more important. In summary, this study argues for adopting low glycemic index diets with lower protein content for weight loss and maintenance.
The strengths of this study are that the subjects were otherwise healthy without diabetes, morbid obesity, and other chronic diseases. Also, the study separated the effects of weight loss from the effects of dietary composition. However, it must be emphasized that the effects of weight loss on all the metabolic, inflammatory, and blood pressure measures was greater than the effects of dietary composition.
Carbohydrate restriction uniquely benefits metabolic syndrome and saturated fat metabolism
SOURCE: http://www.biomedcentral.com/1753-6561/6/S3/O27
Jeff S Volek
From Metabolism, diet and disease
Washington, DC, USA. 29-31 May 2012
Metabolic syndrome (insulin resistance syndrome) represents a group of physiologic signs that indicate a predisposition to obesity, diabetes, and cardiovascular disease. Consistent with the idea that intolerance to carbohydrate is an underlying feature of metabolic syndrome, we present results showing that a low carbohydrate diet results in global improvement in traditional and emerging markers associated with metabolic syndrome. Control diets, restricted in fat, are shown to be less effective. Recent research results mandate a careful re-evaluation of the widespread belief that dietary saturated fat is harmful. Specifically, multiple recent reports find no association between dietary saturated fat intakes and cardiovascular disease (CVD). There is, however, a consistent pattern of increased risk for both CVD and type-2 diabetes associated with increased levels of saturated fatty acids (SFA) in circulating lipids. This raises the important question as to what contributes to increased levels of saturated fat in the blood? Whereas dietary intake of saturated fats and serum levels of SFA show virtually no correlation, an increased intake of carbohydrate is associated with higher levels of circulating SFA. This leads to the paradoxical conclusion that dietary saturated fat is not the problem; rather it’s the over-consumption of carbohydrate relative to the individual’s ability to metabolize glucose without resorting to de novo lipogenesis. From this perspective, insulin resistant states like metabolic syndrome and type-2 diabetes can be viewed as carbohydrate intolerance, in which a high carbohydrate intake translates to increased serum SFA and therefore increased risk. We all stand to benefit, both now and in the future, if a well-formulated low carbohydrate diet becomes an accepted option in promoting health across many sub-groups in our population.
Published: 1 June 2012
doi:10.1186/1753-6561-6-S3-O27
Volek: Carbohydrate restriction uniquely benefits
metabolic syndrome and saturated fat metabolism. BMC Proceedings
2012 6(Suppl 3):O27
Differential effects of high-carbohydrate and high-fat diet composition on metabolic control and insulin resistance in normal rats
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22754464
by Ble-Castillo, Jorge L; Aparicio-Trapala, María A; Juárez-Rojop, Isela E; Torres-Lopez, Jorge E; Mendez, Jose D; Aguilar-Mariscal, Hidemi (more...)
Abstract
The macronutrient component of diets is critical for metabolic control and insulin action. The aim of this study was to compare the effects of high fat diets (HFDs) vs. high carbohydrate diets (HCDs) on metabolic control and insulin resistance in Wistar rats. Thirty animals divided into five groups (n = 6) were fed: (1) Control diet (CD); (2) High-saturated fat diet (HSFD); (3) High-unsaturated fat diet (HUFD); (4) High-digestible starch diet, (HDSD); and (5) High-resistant starch diet (HRSD) during eight weeks. HFDs and HCDs reduced weight gain in comparison with CD, however no statistical significance was reached. Calorie intake was similar in both HFDs and CD, but rats receiving HCDs showed higher calorie consumption than other groups, (p < 0.01). HRSD showed the lowest levels of serum and hepatic lipids. The HUFD induced the lowest fasting glycemia levels and HOMA-IR values. The HDSD group exhibited the highest insulin resistance and hepatic cholesterol content. In conclusion, HUFD exhibited the most beneficial effects on glycemic control meanwhile HRSD induced the highest reduction on lipid content and did not modify insulin sensitivity. In both groups, HFDs and HCDs, the diet constituents were more important factors than caloric intake for metabolic disturbance and insulin resistance.
International journal of environmental research and public health
Three weight-loss diets yield varied metabolic effects
SOURCE: http://www.thefreelibrary.com/Three+weight-loss+diets+yield+varied+metabolic+effects.-a0299640041
Author(s): Mary Ann Moon
Source: Internal Medicine News. 45.12 (July 1, 2012): p7.
Document Type: Article
Three different diets designed to maintain a recent weight loss were found to exert markedly different metabolic effects independently of their energy content in obese and overweight young adults.
"The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective," said Cara B. Ebbeling, Ph.D., of the New Balance Foundation Obesity Prevention Center, Children's Hospital Boston, and her associates.
During the run-in phase of the study, 32 subjects aged 18-40 years with a body mass index of 27 or higher followed a standard low-calorie diet that restricted energy intake to achieve a 12.5% decrease in body weight. Detailed assessments also were done to establish each subject's energy requirements for stabilizing their weight at this reduced level.
After the subjects achieved a 10%-15% weight reduction, they each consumed one of the three isocaloric diets for 4 weeks, then switched to another of the diets for another 4 weeks, then to the third diet for a final 4 weeks in a three-way crossover design.
The three diets were the following: a low-fat diet with a high glycemic load and 20% of energy from protein, which reflected conventional recommendations to reduce fat, increase whole grain products, and include a variety of vegetables and fruits; a low-glycemic-index diet with moderate glycemic load and and 20% of energy from protein, which replaced some grain products and starchy vegetables with other vegetables, legumes, and fruits; and a very-low-carbohydrate diet with a low glycemic load and 30% of energy from protein, which was modeled on the Atkins diet.
Both resting energy expenditure and total energy expenditure decreased with all the diets, but the decrease was significantly greater with the low-fat diet. In addition, serum leptin levels were highest with the low-fat diet. These two findings suggest that people following the low-fat diet would be more likely to regain weight than those following the other diets, the investigators said (JAMA 2012;307: 2627-34).
Moreover, the low-fat diet also had the most unfavorable effects on peripheral and hepatic insulin sensitivity, serum HDL cholesterol, triglycerides, and plasminogen activator inhibitor 1.
In contrast, the very-low-carbohydrate diet had the most favorable effects on these components of the metabolic syndrome and on energy expenditure.
The very-low-carbohydrate diet, however, produced higher C-reactive protein levels and higher cortisol excretion levels than the other diets, both of which signal physiological stress and chronic inflammation.
This study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center for Research Resources, and the New Balance Foundation.
Moon, Mary Ann
Source Citation (MLA 7th Edition)
Moon, Mary Ann. "Three weight-loss diets yield varied metabolic effects." Internal Medicine News 1 July 2012: 7. Academic OneFile. Web. 2 Oct. 2012.
I'm in the middle of writing my midterm paper for my Integrative Human Systems Physiology Class and I seriously need to take a break. :noway:
The assignment is to write a 27-page paper explaining how over-consumption of dietary carbohydrates leads to weight-gain in the general population and it's mechanisms. I'm on page 18 and my head is starting to hurt so I figured I would take a break and share with you what I'm learning since some of you may be interested! :flowerforyou
I figured the best way to share my learning experience is to just simply share some of my sources. That way we can avoid any discrepancies concerning the 'accuracy' of my information. :huh:
So here you go!
Oh, and P.S. All of these articles were published in 2012.
Cheers! :drinker:
Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22673594
Talib A. Hussain, M.B., Ch.B., R.C.G.P.a, Thazhumpal C. Mathew, M.Sc., Ph.D., F.R.C.Path.b, Ali A. Dashti, M.Sc., Ph.D.b, Sami Asfar, M.B., Ch.B., M.D., F.R.C.S., F.A.C.S.c, Naji Al-Zaid, B.Sc., Ph.D.d, Hussein M. Dashti, M.D., Ph.D., F.I.C.S., F.A.C.S.c, ,
Abstract
Effective diabetic management requires reasonable weight control. Previous studies from our laboratory have shown the beneficial effects of a low-carbohydrate ketogenic diet (LCKD) in patients with type 2 diabetes after its long term administration. Furthermore, it favorably alters the cardiac risk factors even in hyperlipidemic obese subjects. These studies have indicated that, in addition to decreasing body weight and improving glycemia, LCKD can be effective in decreasing antidiabetic medication dosage. Similar to the LCKD, the conventional low-calorie, high nutritional value diet is also used for weight loss. The purpose of this study was to understand the beneficial effects of LCKD compared with the low-calorie diet (LCD) in improving glycemia.
Methods
Three hundred and sixty-three overweight and obese participants were recruited from the Al-Shaab Clinic for a 24-wk diet intervention trial; 102 of them had type 2 diabetes. The participants were advised to choose LCD or LDKD, depending on their preference. Body weight, body mass index, changes in waist circumference, blood glucose level, changes in hemoglobin and glycosylated hemoglobin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, urea and creatinine were determined before and at 4, 8, 12, 16, 20, and 24 wk after the administration of the LCD or LCKD. The initial dose of some antidiabetic medications was decreased to half and some were discontinued at the beginning of the dietary program in the LCKD group. Dietary counseling and further medication adjustment were done on a biweekly basis.
Results
The LCD and LCKD had beneficial effects on all the parameters examined. Interestingly, these changes were <b>more significant</b> in subjects who were on the LCKD as compared with those on the LCD. Changes in the level of creatinine were not statistically significant.
Conclusion
This study shows the beneficial effects of a ketogenic diet over the conventional LCD in obese diabetic subjects. The ketogenic diet appears to improve glycemic control. Therefore, diabetic patients on a ketogenic diet should be under strict medical supervision because the LCKD can significantly lower blood glucose levels.
Effect of a low-carbohydrate, ketogenic diet program compared to a low-fat diet on fasting lipoprotein subclasses
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/16297472
Eric C. Westmana, William S. Yancy Jr.a, b, Maren K. Olsenb, c, Tara Dudleyb, John R. Guytona
• a Department of Medicine, Duke University Medical Center, Durham, NC, USA
• b Center for Health Services Research in Primary Care, Department of Veterans' Affairs Medical Center, Durham, NC, USA
• c Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA
Abstract
Background
Low-carbohydrate, ketogenic diets (LCKD) are effective for weight loss, <b>but concerns remain regarding cardiovascular risk.</b> The purpose of this study was to determine the effect of an LCKD program on serum lipoprotein subclasses.
Methods
This was a randomized, two-arm clinical trial in an outpatient research clinic involving overweight, hyperlipidemic community volunteers motivated to lose weight. Subjects were randomized to either an LCKD (n = 59) and nutritional supplementation (including fish, borage and flaxseed oil), or a low-fat, reduced-calorie diet (LFD, n = 60). The main outcomes were fasting serum lipoprotein subclasses determined by nuclear magnetic resonance analysis.
Results
The mean age of subjects was 44.9 years, the mean BMI was 34.4 kg/m2, and 76% were women. Comparing baseline to 6 months, the LCKD group had significant changes in large VLDL (− 78%), medium VLDL (− 60%), small VLDL (− 57%), LDL particle size (+ 2%), large LDL (+ 54%), medium LDL (− 42%), small LDL (− 78%), HDL particle size (+ 5%), large HDL (+ 21%), and LDL particle concentration (− 11%). Compared with the LFD group, the LCKD group had greater reductions in medium VLDL (p = 0.01), small VLDL (p = 0.01) and medium LDL (p = 0.02), and greater increases in VLDL particle size (p = 0.01), large LDL (p = 0.004), and HDL particle size (p = 0.05).
Conclusions
The LCKD with nutritional supplementation led to beneficial changes in serum lipid subclasses during weight loss. <b>While the LCKD did not lower total LDL cholesterol, it did result in a shift from small, dense LDL to large, buoyant LDL, which could lower cardiovascular disease risk.</b>
Low-carbohydrate diet bested standard calorie restriction for lowering glucose levels, weight loss
SOURCE: http://www.healio.com/footer/account-information/login?returnUrl=/endocrinology/obesity/news/print/endocrine-today/{75887CF5-7B4B-4F01-9DEC-CC4C05F9A67E}/Low-carbohydrate-diet-bested-standard-calorie-restriction-for-lowering-glucose-levels-weight-loss
Foster, Melissa; Shafer, Emily. Endocrine Today 10. 1 (Jan 2012): 16.
Adhering to a strict, low-carbohydrate diet 2 days per week led to greater reductions in weight and insulin levels when compared with standard daily dieting.
Weight loss and reduced insulin levels are required for breast cancer prevention, but [these levels] are difficult to achieve and maintain with conventional dietary approaches," Michelle Harvie, PhD, registered dietitian at the Genesis Prevention Center at the University Hospital in South Manchester, England, said in a press release.
To investigate the efficacy and feasibility of two intermittent, low-carbohydrate diets, Harvie and colleagues randomly assigned 115 overweight or obese women at increased risk for breast cancer to three different diets for 4 months: a low-carbohydrate, restricted calorie diet for 2 days per week; an "ad lib" low-carbohydrate diet that included other foods such as protein for 2 days per week; and a standard daily restricted Mediterranean diet.
Patients in the standard diet group experienced 2.4-kg weight loss (95% CI, 1.2-3.4), researchers said. Patients in the restricted low-carbohydrate diet group lost 4.3 kg (95% CI, 3-5.6), and patients in the ad lib low-carbohydrate diet lost 4.1 kg (95% CI, 3.1-5.2), researchers said.
"It is interesting that the diet that only restricts carbohydrates, but allows proteins and fats, is as effective as the calorie- restricted, low-carbohydrate diet," Harvie said.
Additionally, patients in the intermittent, low-carbohydrate diet study arms demonstrated greater reductions in insulin resistance vs. those in the standard diet arm. Mean difference from baseline to study conclusion was 22% for patients in the restricted-calorie group and 14% in the ad lib group vs. 4% in the standard diet group, according to the data.
"Greater weight loss, fewer dropouts and greater reductions in insulin resistance with the novel intermittent and low-carbohydrate diets indicate that these are alternative approaches for energy restriction for potentially reducing risk for breast cancer and other diseases," the researchers concluded.
No changes in time trial performance of master endurance athletes after 4 weeks on a low carbohydrate diet
SOURCE: http://rd.springer.com/article/10.1007/s11332-012-0129-2
Maria Francesca Piacentini, Attilio Parisi, Nicole Verticchio, Stefania Comotto, Romain Meeusen and Laura Capranica
Abstract
The purpose of the present study was to evaluate the effects of a 4-week low-carbohydrate (CHO) diet regimen on body weight, exercise performance and hormonal response to running in master athletes. Six endurance master athletes performed three 30-min time trials, before (TT1), after 15 days (TT2) and after 30 days (TT3) on a low CHO diet. Blood samples were collected for hormonal and lactate measurements. After 15 days body weight had decreased (TT1 72.3 ± 2.4 kg, TT2 70.0 ± 2.7 kg; P = 0.006) and then remained stable. No differences were observed in performance (TT1 7,015 ± 273 m, TT2 6,920 ± 286 m, TT3 7,202 ± 315 m) and in the insulin/glucagon ratio. After 2 and 4 weeks, adrenocorticotropic hormone decreased significantly both at rest (baseline: TT1 42.5 ± 7.8 pg•ml−1, TT3 21.6 ± 3.2 pg•ml−1) and during exercise (end of exercise: TT1 120 ± 20 pg•ml−1, TT2 80 ± 16 pg•ml−1, TT3 31 ± 2 pg•ml−1). Baseline cortisol concentrations had increased significantly after as little as 15 days on the low CHO diet. The results of the present study demonstrate no changes in time trial performance in master endurance athletes after 4 weeks on a low CHO diet. However, an effect on the hypothalamic pituitary adrenal axis emerged.
Low-carbohydrate high-fat diets in combination with daily exercise in rats: effects on body weight regulation, body composition and exercise capacity
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22342194
by Caton, Samantha J; Obici, Silvana; Kienzle, Ellen; Tschöp, Matthias H; Bidlingmaier, Martin; Bielohuby, Maximilian (more...)
Abstract
The aim of the current investigation was to examine the effects of consuming a low-carbohydrate high-fat diet (LC-HFD) in combination with daily exercise on body weight, body composition, endocrine control of the energy balance system and exercise capacity in adolescent and mature rats. Adolescent (n=23) and mature rats (n=16) were maintained on either a standard chow diet (CH) or a LC-HFD for a period of ten days prior to daily exercise training for 21 days in forced running wheel system. At the end of the 21 day training sessions all rats took part in an exercise performance test where time to exhaustion was measured. Rats maintained on the LC-HFD demonstrated a significant lack of body weight gain (p<0.05) compared to CH maintained rats, despite equicaloric intake and performing identical amounts of daily exercise. Body composition was significantly altered in the LC-HFD rats (p<0.05) with increased body fat (p<0.01). Leptin concentrations were higher (p<0.05) and IGF-I concentrations were lower (p<0.01) in the LC-HFD fed rats. Exercise performance was not diminished in the LC-HFD group despite the higher fat mass. Both groups irrespective of age performed equally as well in the time to exhaustion test (p>0.05). Maintenance on the LC-HFD in combination with forced daily exercise did not impact exercise capacity (total distance and meters per minute). <b>Additionally consumption of an extreme LC-HFD in combination with daily exercise resulted in significantly less body weight gain but increased fat mass. When combined with daily exercise this diet clearly had a negative impact on body composition, but did not affect exercise capacity.</b>
Optimal Weight Loss Diet to Reduce Cardiovascular Risk
Source: Clinical Cardiology Alert. (Feb. 1, 2012):
Document Type: Clinical report
SOURCE: http://www.highbeam.com/doc/1G1-285208898.html
Abstract & Commentary
By Michael H. Crawford, MD, Editor
Source: Gogebakan O, et al.
Effects of weight loss and long-term maintenance with diets varying in protein and glycemic index on cardiovascular risk factors: The Diet, Obesity, and Genes (DiOGenes) study: A randomized controlled trial. Circulation 2011;124:2829-2838.
This pan-European multicultural study investigates whether after initial weight loss in overweight subjects, a subsequent diet of high or low carbohydrate (glycemic index) or protein diets helped subjects maintain their new weight better. Their initial results showed that the low glycemic, high-protein diet was superior for maintaining their weight for 26 weeks. The present study evaluated which diet best improved hsCRP, triglycerides, cholesterol levels, and blood pressure vs a control group in 932 overweight adults who lost weight on an 8-week low-calorie diet. Of the 773 randomized to one of the four diets, 71% completed the study. Average weight loss in the low-calorie period was 11 kg. Of the subsequent diets, only the low-protein high-glycemic diet resulted in weight regain (+ 1.7 kg). Weight loss reduced hsCRP, cholesterol (HDL and LDL), triglycerides, and blood pressure. During the maintenance phase, hsCRP was reduced further in the low-glycemic diets vs high and on low protein diets vs high. Cholesterol, triglycerides, and blood pressure were not differentially affected by the four diets. The authors conclude that after weight loss, a low glycemic index and, to a lesser extent, low-protein diet may reduce inflammation associated with cardiovascular disease in overweight adults.
Commentary
With two-thirds of American adults being either overweight or obese, scientific data on appropriate diets are important. The original trial report of this study showed that caloric restriction was necessary for weight loss and diet composition had little effect. The emphasis on low-fat diets to reduce cholesterol and reduce cardiovascular risk may be thwarted if subjects substitute carbohydrates for the fat calories, resulting in little or no weight loss. As this follow-up study shows, a high glycemic index diet may also blunt the decrease in low-grade inflammation associated with weight loss and increase cardiovascular risk. Maintaining a high-protein diet also can blunt the decrease in hsCRP following weight loss, but to a much lesser extent than a high-glycemic diet. However, high-protein diets are known to improve lipid profiles. What the balance between lower LDL cholesterol and higher inflammation will do to subsequent cardiovascular risk is not known, but since cholesterol can be lowered by other means, the lower inflammation on a low-glycemic diet could be more important. In summary, this study argues for adopting low glycemic index diets with lower protein content for weight loss and maintenance.
The strengths of this study are that the subjects were otherwise healthy without diabetes, morbid obesity, and other chronic diseases. Also, the study separated the effects of weight loss from the effects of dietary composition. However, it must be emphasized that the effects of weight loss on all the metabolic, inflammatory, and blood pressure measures was greater than the effects of dietary composition.
Carbohydrate restriction uniquely benefits metabolic syndrome and saturated fat metabolism
SOURCE: http://www.biomedcentral.com/1753-6561/6/S3/O27
Jeff S Volek
From Metabolism, diet and disease
Washington, DC, USA. 29-31 May 2012
Metabolic syndrome (insulin resistance syndrome) represents a group of physiologic signs that indicate a predisposition to obesity, diabetes, and cardiovascular disease. Consistent with the idea that intolerance to carbohydrate is an underlying feature of metabolic syndrome, we present results showing that a low carbohydrate diet results in global improvement in traditional and emerging markers associated with metabolic syndrome. Control diets, restricted in fat, are shown to be less effective. Recent research results mandate a careful re-evaluation of the widespread belief that dietary saturated fat is harmful. Specifically, multiple recent reports find no association between dietary saturated fat intakes and cardiovascular disease (CVD). There is, however, a consistent pattern of increased risk for both CVD and type-2 diabetes associated with increased levels of saturated fatty acids (SFA) in circulating lipids. This raises the important question as to what contributes to increased levels of saturated fat in the blood? Whereas dietary intake of saturated fats and serum levels of SFA show virtually no correlation, an increased intake of carbohydrate is associated with higher levels of circulating SFA. This leads to the paradoxical conclusion that dietary saturated fat is not the problem; rather it’s the over-consumption of carbohydrate relative to the individual’s ability to metabolize glucose without resorting to de novo lipogenesis. From this perspective, insulin resistant states like metabolic syndrome and type-2 diabetes can be viewed as carbohydrate intolerance, in which a high carbohydrate intake translates to increased serum SFA and therefore increased risk. We all stand to benefit, both now and in the future, if a well-formulated low carbohydrate diet becomes an accepted option in promoting health across many sub-groups in our population.
Published: 1 June 2012
doi:10.1186/1753-6561-6-S3-O27
Volek: Carbohydrate restriction uniquely benefits
metabolic syndrome and saturated fat metabolism. BMC Proceedings
2012 6(Suppl 3):O27
Differential effects of high-carbohydrate and high-fat diet composition on metabolic control and insulin resistance in normal rats
SOURCE: http://www.ncbi.nlm.nih.gov/pubmed/22754464
by Ble-Castillo, Jorge L; Aparicio-Trapala, María A; Juárez-Rojop, Isela E; Torres-Lopez, Jorge E; Mendez, Jose D; Aguilar-Mariscal, Hidemi (more...)
Abstract
The macronutrient component of diets is critical for metabolic control and insulin action. The aim of this study was to compare the effects of high fat diets (HFDs) vs. high carbohydrate diets (HCDs) on metabolic control and insulin resistance in Wistar rats. Thirty animals divided into five groups (n = 6) were fed: (1) Control diet (CD); (2) High-saturated fat diet (HSFD); (3) High-unsaturated fat diet (HUFD); (4) High-digestible starch diet, (HDSD); and (5) High-resistant starch diet (HRSD) during eight weeks. HFDs and HCDs reduced weight gain in comparison with CD, however no statistical significance was reached. Calorie intake was similar in both HFDs and CD, but rats receiving HCDs showed higher calorie consumption than other groups, (p < 0.01). HRSD showed the lowest levels of serum and hepatic lipids. The HUFD induced the lowest fasting glycemia levels and HOMA-IR values. The HDSD group exhibited the highest insulin resistance and hepatic cholesterol content. In conclusion, HUFD exhibited the most beneficial effects on glycemic control meanwhile HRSD induced the highest reduction on lipid content and did not modify insulin sensitivity. In both groups, HFDs and HCDs, the diet constituents were more important factors than caloric intake for metabolic disturbance and insulin resistance.
International journal of environmental research and public health
Three weight-loss diets yield varied metabolic effects
SOURCE: http://www.thefreelibrary.com/Three+weight-loss+diets+yield+varied+metabolic+effects.-a0299640041
Author(s): Mary Ann Moon
Source: Internal Medicine News. 45.12 (July 1, 2012): p7.
Document Type: Article
Three different diets designed to maintain a recent weight loss were found to exert markedly different metabolic effects independently of their energy content in obese and overweight young adults.
"The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective," said Cara B. Ebbeling, Ph.D., of the New Balance Foundation Obesity Prevention Center, Children's Hospital Boston, and her associates.
During the run-in phase of the study, 32 subjects aged 18-40 years with a body mass index of 27 or higher followed a standard low-calorie diet that restricted energy intake to achieve a 12.5% decrease in body weight. Detailed assessments also were done to establish each subject's energy requirements for stabilizing their weight at this reduced level.
After the subjects achieved a 10%-15% weight reduction, they each consumed one of the three isocaloric diets for 4 weeks, then switched to another of the diets for another 4 weeks, then to the third diet for a final 4 weeks in a three-way crossover design.
The three diets were the following: a low-fat diet with a high glycemic load and 20% of energy from protein, which reflected conventional recommendations to reduce fat, increase whole grain products, and include a variety of vegetables and fruits; a low-glycemic-index diet with moderate glycemic load and and 20% of energy from protein, which replaced some grain products and starchy vegetables with other vegetables, legumes, and fruits; and a very-low-carbohydrate diet with a low glycemic load and 30% of energy from protein, which was modeled on the Atkins diet.
Both resting energy expenditure and total energy expenditure decreased with all the diets, but the decrease was significantly greater with the low-fat diet. In addition, serum leptin levels were highest with the low-fat diet. These two findings suggest that people following the low-fat diet would be more likely to regain weight than those following the other diets, the investigators said (JAMA 2012;307: 2627-34).
Moreover, the low-fat diet also had the most unfavorable effects on peripheral and hepatic insulin sensitivity, serum HDL cholesterol, triglycerides, and plasminogen activator inhibitor 1.
In contrast, the very-low-carbohydrate diet had the most favorable effects on these components of the metabolic syndrome and on energy expenditure.
The very-low-carbohydrate diet, however, produced higher C-reactive protein levels and higher cortisol excretion levels than the other diets, both of which signal physiological stress and chronic inflammation.
This study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center for Research Resources, and the New Balance Foundation.
Moon, Mary Ann
Source Citation (MLA 7th Edition)
Moon, Mary Ann. "Three weight-loss diets yield varied metabolic effects." Internal Medicine News 1 July 2012: 7. Academic OneFile. Web. 2 Oct. 2012.
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OH well done you! I've read some of the research on sites we have access to through the college I teach at. I don't have an account for the American Journal of Medicine, there was another I couldn't get to the papers called the Diabetic something something society and there was one other website of research at the University of Oklahoma and I couldn't open any of that either.
Thanks for this. I'll copy and paste it and keep it in a file on a USB. Much appreciated indeed.
Mathematics is the language of nature.0 -
thanks katastic!!0
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Thanks for the info. Just by experimenting, I have found a low-carb diet best for me (I am pre-diabetic). Interesting to see there's so much research to back it up too.0
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Thank you for such an interesting survey of the papers you have been reading. I have read a number of books on this subject (including one co-authored by one of the researchers you abstract, Volek), but it is great to know what the latest research is suggesting, since these post-date nearly all the books. Interestingly, the 2012 articles you cite reinforce many of the points raised in the books:
--Very low-carb diets produce generally quicker fat loss than other diets; low-carbohydrate consumption seems to stabilize fasting blood glucose, lower triglycerides significantly, lower total cholesterol, raise HDL and generally leave LDL levels alone (but with suggestions that LDL particle size increases, which is thought to be good.) I have read that a measure of LDL size is indicated by the ratio of total cholesterol to HDL; a ratio of less than 4.4 is considered a good sign (i.e. of larger LDL particles.)
But the articles you have collected also seem to raise the possibility that low-carb diets increase cortisol, which is a sign of stress, which in turn is associated with increased inflammation -- those two are not so positive. Unfortunately, these are not discussed in the books I read but have been described in a number of Internet blogs and discussions, particularly those that are opposed to low-carb routines. (I don't have those at my fingertip at the moment.) It seems to me (as a former college writing instructor) that your paper should not fail to note those issues very directly; doing so will strengthen the objectivity of your work.
If low-carb diets are conclusively found to be effective at lowering blood lipids, fasting glucose and of course weight, it may be that certain adjustments could be used to also limit less favorable cortisol rises. Such as: Vitamins? Herbs? Yoga? Occasional planned lapses from the diet so as to reduce mental stress caused by thoughts of "I can never eat my favorite comfort food again!" Strenuous exercise? That could be a great area for research. (Hint!)
Anyway, good luck on a great topic and thanks for the effort of sharing so much information.0 -
Sorry -- one more thing:
Gary Taube's "Why We Get Fat" (2011, I believe) explores precisely the topic you are working on and includes many many references.0 -
Thank you for such an interesting survey of the papers you have been reading. I have read a number of books on this subject (including one co-authored by one of the researchers you abstract, Volek), but it is great to know what the latest research is suggesting, since these post-date nearly all the books. Interestingly, the 2012 articles you cite reinforce many of the points raised in the books:
--Very low-carb diets produce generally quicker fat loss than other diets; low-carbohydrate consumption seems to stabilize fasting blood glucose, lower triglycerides significantly, lower total cholesterol, raise HDL and generally leave LDL levels alone (but with suggestions that LDL particle size increases, which is thought to be good.) I have read that a measure of LDL size is indicated by the ratio of total cholesterol to HDL; a ratio of less than 4.4 is considered a good sign (i.e. of larger LDL particles.)
But the articles you have collected also seem to raise the possibility that low-carb diets increase cortisol, which is a sign of stress, which in turn is associated with increased inflammation -- those two are not so positive. Unfortunately, these are not discussed in the books I read but have been described in a number of Internet blogs and discussions, particularly those that are opposed to low-carb routines. (I don't have those at my fingertip at the moment.) It seems to me (as a former college writing instructor) that your paper should not fail to note those issues very directly; doing so will strengthen the objectivity of your work.
If low-carb diets are conclusively found to be effective at lowering blood lipids, fasting glucose and of course weight, it may be that certain adjustments could be used to also limit less favorable cortisol rises. Such as: Vitamins? Herbs? Yoga? Occasional planned lapses from the diet so as to reduce mental stress caused by thoughts of "I can never eat my favorite comfort food again!" Strenuous exercise? That could be a great area for research. (Hint!)
Anyway, good luck on a great topic and thanks for the effort of sharing so much information.
I am SUPER interested in this!! I had no idea it raised cortisol!0 -
Thank you for such an interesting survey of the papers you have been reading. I have read a number of books on this subject (including one co-authored by one of the researchers you abstract, Volek), but it is great to know what the latest research is suggesting, since these post-date nearly all the books. Interestingly, the 2012 articles you cite reinforce many of the points raised in the books:
--Very low-carb diets produce generally quicker fat loss than other diets; low-carbohydrate consumption seems to stabilize fasting blood glucose, lower triglycerides significantly, lower total cholesterol, raise HDL and generally leave LDL levels alone (but with suggestions that LDL particle size increases, which is thought to be good.) I have read that a measure of LDL size is indicated by the ratio of total cholesterol to HDL; a ratio of less than 4.4 is considered a good sign (i.e. of larger LDL particles.)
But the articles you have collected also seem to raise the possibility that low-carb diets increase cortisol, which is a sign of stress, which in turn is associated with increased inflammation -- those two are not so positive. Unfortunately, these are not discussed in the books I read but have been described in a number of Internet blogs and discussions, particularly those that are opposed to low-carb routines. (I don't have those at my fingertip at the moment.) It seems to me (as a former college writing instructor) that your paper should not fail to note those issues very directly; doing so will strengthen the objectivity of your work.
If low-carb diets are conclusively found to be effective at lowering blood lipids, fasting glucose and of course weight, it may be that certain adjustments could be used to also limit less favorable cortisol rises. Such as: Vitamins? Herbs? Yoga? Occasional planned lapses from the diet so as to reduce mental stress caused by thoughts of "I can never eat my favorite comfort food again!" Strenuous exercise? That could be a great area for research. (Hint!)
Anyway, good luck on a great topic and thanks for the effort of sharing so much information.
I am SUPER interested in this!! I had no idea it raised cortisol!
Oh yes love. Low-Carb diets raise cortisol significantly! However, for some people (metabolically resistant individuals) low-carb is simply the lesser of two evils, but by no means is it flawless.0 -
Thank you for such an interesting survey of the papers you have been reading. I have read a number of books on this subject (including one co-authored by one of the researchers you abstract, Volek), but it is great to know what the latest research is suggesting, since these post-date nearly all the books. Interestingly, the 2012 articles you cite reinforce many of the points raised in the books:
--Very low-carb diets produce generally quicker fat loss than other diets; low-carbohydrate consumption seems to stabilize fasting blood glucose, lower triglycerides significantly, lower total cholesterol, raise HDL and generally leave LDL levels alone (but with suggestions that LDL particle size increases, which is thought to be good.) I have read that a measure of LDL size is indicated by the ratio of total cholesterol to HDL; a ratio of less than 4.4 is considered a good sign (i.e. of larger LDL particles.)
But the articles you have collected also seem to raise the possibility that low-carb diets increase cortisol, which is a sign of stress, which in turn is associated with increased inflammation -- those two are not so positive. Unfortunately, these are not discussed in the books I read but have been described in a number of Internet blogs and discussions, particularly those that are opposed to low-carb routines. (I don't have those at my fingertip at the moment.) It seems to me (as a former college writing instructor) that your paper should not fail to note those issues very directly; doing so will strengthen the objectivity of your work.
If low-carb diets are conclusively found to be effective at lowering blood lipids, fasting glucose and of course weight, it may be that certain adjustments could be used to also limit less favorable cortisol rises. Such as: Vitamins? Herbs? Yoga? Occasional planned lapses from the diet so as to reduce mental stress caused by thoughts of "I can never eat my favorite comfort food again!" Strenuous exercise? That could be a great area for research. (Hint!)
Anyway, good luck on a great topic and thanks for the effort of sharing so much information.
Yes. Low-carb diets SIGNIFICANTLY increase cortisol levels, but like I said for some people (metabolically resistant people, myself included) a low-carb diet is the lesser of two evils, but by NO MEANS is it flawless. If you are steadfast in believing that low-carb is the answer to everything for everybody it's time for a major paradigm shift. Low-Carb has it's problems to.
As well intentioned as these books may be, that just goes to show that they illuminate only one side of the story and are not objective.Unfortunately, these are not discussed in the books I read
Opposing views are important to consider for they help point us along our way to the objective truth.0 -
I read a few things online about the whole cortisol thing... could it be from eating crappy low carb foods - like low carb tortillas? or does it happen no matter what? Could it happen more if we eat too much protein and not enough fat and we have to keep converting the protein to get energy?
I would love to know more about this... I had NO idea!0
