The #1 Cause of Obesity: Insulin

Did I hear someone say Lustig?

I'll start with this. http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-about-fructose-alarmism/

Ok, now that that's out of the way. Insulin has pretty much nothing to do with obesity.

Does insulin prevent lipolysis? No. Does it reduce lipolysis? Of course it does, you've just eaten. When you eat food, your body uses the food for energy first, and only goes back to relying on lipolysis after the food has been fully digested and utilized. Leptin (the hormone that signals satiety) has also been shown to limit lipolysis. As has every other hormone that has to do with satiety.

Does insulin shuttle glucose directly to fat storage? NO. Absolutely not. Glucose is almost NEVER stored as fat. Insulin's primary job is to transport glucose to muscle cells and vital organs for normal body function. 87% of the fat in an adipose cell comes from lipids, not triglycerides.

Insulin is a key hormone in muscle building and maintenance. It has well over 100 functions in the human body, fat storage is nowhere near the top of the list.

And how do you care to explain protein eliciting high insulin responses? Protein and carbohydrates both spike insulin to similar levels when you eat. If insulin is what makes us fat, then protein must be just as bad as carbs.

The entire argument is based on fear, and a hope that the person they are trying to convince has a lack of understanding of human biology. The insulin hypothesis just doesn't stand up to actual facts.

As for low carb vs higher carb. They both cause weight loss due to a calorie deficit. Protein should always be constant, regardless of carb level. And then "weight loss" is a misleading term. Low carb diets lead to much higher losses of water weight, due to the reduction of stored glycogen in the muscles. Fat loss is identical, regardless of carb level.

How many of them matched calories and protein? Metabolic ward studies (self reported data is ridiculously unreliable). Get back to me when you read and understand what the studies are saying.

Show us a list of studies that meet your standards and show that low carb diets are worse please ? Seems to me they either come out better or the same,

In 7 of the 10 studies, there was no difference in resting or sleeping metabolic rate.33-39 When fat was substituted for carbohydrate (keeping protein matched), the 24-hour energy expenditure of the groups did not differ. In two studies that included a post- obese subgroup, 24-hour energy expenditure decreased 75–80 calories per day as a result of the higher fat intake. When the results of all 10 studies were averaged, there was zero difference in 24-hour energy expenditure between the high-carbohydrate and high-fat diets. AARR, June 2009

28. Schoeller DA, Buchholz AC. Energetics of obesity and weight control: does diet composition matter? J Am Diet Assoc. 2005 May;105(5 Suppl 1):S24-8. [Medline]

29. Schoeller DA, Buchholz AC. Is a calorie a calorie? Am J Clin Nutr. 2004 May;79(5):899S-906S. [Medline]

30. Davy KP, et al. Regulation of macronutrient balance in healthy young and older men. Int J Obes Relat Metab Disord. 2001 Oct;25(10):1497-502. [Medline]

31. Roy HJ, et al. Substrate oxidation and energy expenditure in athletes and nonathletes consuming isoenergetic high- and low- fat diets. Am J Clin Nutr. 1998 Mar;67(3):405-11. [Medline]

32. Thomas CD, et al. Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans. Am J Clin Nutr. 1992 May;55(5):934-42. [Medline]

33. Hill JO, et al. Nutrient balance in humans: effects of diet composition. Am J Clin Nutr. 1991 Jul;54(1):10-7. [Medline]
34. Rumpler WV, et al. Energy-intake restriction and diet- composition effects on energy expenditure in men. Am J Clin Nutr. 1991 Feb;53(2):430-6. [Medline]

35. Lean ME, James WP. Metabolic effects of isoenergetic nutrient exchange over 24 hours in relation to obesity in women. Int J Obes. 1988;12(1):15-27. [Medline]

36. Abbott WG, et al. Energy expenditure in humans: effects of dietary fat and carbohydrate. Am J Physiol. 1990 Feb;258(2 Pt 1):E347-51. [Medline]

37. Yerboeket-van de Venne WP, Westerterp KR. Effects of dietary fat and carbohydrate exchange on human energy metabolism. Appetite. 1996 Jun;26(3):287-300. [Medline]

38. Astrup A, et al. Failure to increase lipid oxidation in response to increasing dietary fat content in formerly obese women. Am J Physiol. 1994 Apr;266(4 Pt 1):E592-9. [Medline]

39. Whitehead JM, McNeill G, Smith JS. The effect of protein intake on 24-h energy expenditure during energy restriction. Int J Obes Relat Metab Disord. 1996 Aug;20(8):727-32. [Medline]

I don't see why calories and protein should be matched, if a low carb diet has more protein than a high carb diet that's part of the story - comparing A with B.

If protein and calories are matched,, varying levels of carbohydrate and fat makee NO DIFFERENCE. If you want to point the finger at a single macronutrient, you can't vary all three and hope to come to any reasonable conclusion (although this is one of the preferred tricks by carbophobes).

Likewise if people can happily eat 1200 calories on a self selected low carb diet but are sawing their fingers off on 1600 calories of high carb diet is this not an argument in favour of the low carb diet as well ?

Individual and highly variable. And nothing to do with insulin.

I happen to agree that reasonably high protein and calorie control are important aspects, but if we're looking for a comparison between the **** people eat normally and something that will take weight off their overhanging gut we just need something that works, for whatever reason.

No we aren't. We're comparing diets. And low-carb diets are no more effective than any other.

I'm not convinced insulin is the cause of obesity, but it inhibits lipolysis so when trying to lose weight the less of it the better.

You forget that it also promotes protein synthesis and inhibits protein degradation.

Did I hear someone say Lustig?

I'll start with this. http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-about-fructose-alarmism/

Ok, now that that's out of the way. Insulin has pretty much nothing to do with obesity.

Does insulin prevent lipolysis? No. Does it reduce lipolysis? Of course it does, you've just eaten. When you eat food, your body uses the food for energy first, and only goes back to relying on lipolysis after the food has been fully digested and utilized. Leptin (the hormone that signals satiety) has also been shown to limit lipolysis. As has every other hormone that has to do with satiety.

Does insulin shuttle glucose directly to fat storage? NO. Absolutely not. Glucose is almost NEVER stored as fat. Insulin's primary job is to transport glucose to muscle cells and vital organs for normal body function. 87% of the fat in an adipose cell comes from lipids, not triglycerides.

Insulin is a key hormone in muscle building and maintenance. It has well over 100 functions in the human body, fat storage is nowhere near the top of the list.

And how do you care to explain protein eliciting high insulin responses? Protein and carbohydrates both spike insulin to similar levels when you eat. If insulin is what makes us fat, then protein must be just as bad as carbs.

The entire argument is based on fear, and a hope that the person they are trying to convince has a lack of understanding of human biology. The insulin hypothesis just doesn't stand up to actual facts.

As for low carb vs higher carb. They both cause weight loss due to a calorie deficit. Protein should always be constant, regardless of carb level. And then "weight loss" is a misleading term. Low carb diets lead to much higher losses of water weight, due to the reduction of stored glycogen in the muscles. Fat loss is identical, regardless of carb level.

This^^ The whole post.

Tagging for further reading on the unicorn studies cited.

ROFL!

Show us a list of studies that meet your standards and show that low carb diets are worse please ? Seems to me they either come out better or the same,

I looked at each of the studies you provided to disprove that and the only thing that stands out to me is "greater average weight losses (2.5 kg over 12 weeks) have been reported for low-carbohydrate diets" and "Further research on differences in the composition of weight loss and on the influence of satiety on compliance with energy-restricted diets is needed to explain the observed increase in weight loss with diets high in protein and/or low in carbohydrate."

Admittedly, I don't understand a lot of what I'm reading but your studies seem to confirm that low carb diets ARE more effective.

28. Schoeller DA, Buchholz AC. Energetics of obesity and weight control: does diet composition matter? J Am Diet Assoc. 2005 May;105(5 Suppl 1):S24-8. [Medline]

Greater average weight losses (2.5 kg over 12 weeks) have been reported for low-carbohydrate diets (<90 g/day) compared with traditional low-fat (<25% of energy), hypocaloric diets, implying a 233 kcal/day greater energy deficit. It has therefore been suggested that a low-carbohydrate diet may provide a metabolic advantage (an increase in energy expenditure), resulting in a positive effect on weight loss and maintenance. However, a review of studies in which 24-hour energy expenditure was measured did not provide evidence to support a metabolic advantage of low-carbohydrate diets and showed little evidence of a metabolic advantage of high-protein (>25% of energy) diets. Nonetheless, diets high in protein, but either low or modest in carbohydrate, have resulted in greater weight losses than traditional low-fat diets.

http://www.ncbi.nlm.nih.gov/pubmed/15867892

29. Schoeller DA, Buchholz AC. Is a calorie a calorie? Am J Clin Nutr. 2004 May;79(5):899S-906S. [Medline]

Further research on differences in the composition of weight loss and on the influence of satiety on compliance with energy-restricted diets is needed to explain the observed increase in weight loss with diets high in protein and/or low in carbohydrate.

http://www.ajcn.org/content/79/5/899S.full

30. Davy KP, et al. Regulation of macronutrient balance in healthy young and older men. Int J Obes Relat Metab Disord. 2001 Oct;25(10):1497-502. [Medline]

To determine the influence of age on the ability to adjust macronutrient oxidation to changes in diet composition. Our hypothesis was that the ability to adjust macronutrient oxidation to changes in diet composition would be impaired with age. I didn't understand what that was saying but here's the link:

http://www.unboundmedicine.com/evidence/ub/citation/11673772/Regulation_of_macronutrient_balance_in_healthy_young_and_older_men_

31. Roy HJ, et al. Substrate oxidation and energy expenditure in athletes and nonathletes consuming isoenergetic high- and low- fat diets. Am J Clin Nutr. 1998 Mar;67(3):405-11. [Medline]

The resoults from this study show that in healthy young men, fuel oxidation shifts both actuely and chromically to apporximate the macronutrient composition of the diet. There were no differences in any aspect of substrate balance in AT athletes, WT athletes, or NA men by group Again, I didn't understand it but I'm not sure that a study on three healthly, athletic men can tell us anything about what's happening is the obese.

http://www.ajcn.org/content/67/3/405.full.pdf

32. Thomas CD, et al. Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans. Am J Clin Nutr. 1992 May;55(5):934-42. [Medline]

To study the influence of diet composition on regulation of body weight, we fed 21 weight-stable subjects (11 lean, 10 obese) high-carbohydrate (HC) and high-fat (HF) diets for 1 wk each. Although diet composition was fixed, total energy intake was unrestricted. Subjects had a higher energy intake on the HF (11,039 +/- 2700 kJ/d) than on the HC (10,672 +/- 2617 kJ/d) diet (P less than 0.05), but energy expenditure was not different between diets. On day 7 of the HC diet, carbohydrate (CHO) oxidation was significantly related to CHO intake with the slope of the regression line 0.99, suggesting that overall CHO balance was near zero. However, the slope of the regression line was greater for obese than for lean subjects. On day 7 of the HF diet, fat oxidation was significantly related to fat intake but the slope of the line was 0.50, suggesting that overall fat balance was positive. However, this relationship was due entirely to lean subjects, with obese subjects showing no relationship between fat intake and oxidation. I'm not sure what the first part is really saying but is the last line saying that lean and obese subjects responded completely different?

http://www.unboundmedicine.com/evidence/ub/citation/1570800/Nutrient_balance_and_energy_expenditure_during_ad_libitum_feeding_of_high_fat_and_high_carbohydrate_diets_in_humans_

33. Hill JO, et al. Nutrient balance in humans: effects of diet composition. Am J Clin Nutr. 1991 Jul;54(1):10-7. [Medline]

The purpose of this study was to examine the effect of alterations in diet composition on energy expenditure and nutrient balance in humans. Eight adults (three men, five women) ate a high-carbohydrate (60% of calories from carbohydrate) and a high-fat (60% of calories from fat) diet for 7 d each according to a randomized, crossover design. Six subjects were studied for an additional week on a mixed diet (45% of calories from fat). For each subject, total caloric intake was identical on all diets and was intended to provide the subject's maintenance energy requirements. All subjects spent days 3 and 7 of each week in a whole-room indirect calorimeter. Diet composition did not affect total daily energy expenditure but did affect daily nutrient oxidation by rapidly shifting substrate oxidation to more closely reflect the composition of the diet. These results show that diet composition can affect substrate oxidation without producing measurable effects on total energy expenditure. What's substrate oxidation?

http://www.unboundmedicine.com/evidence/ub/citation/2058571/Nutrient_balance_in_humans:_effects_of_diet_composition_

34. Rumpler WV, et al. Energy-intake restriction and diet- composition effects on energy expenditure in men. Am J Clin Nutr. 1991 Feb;53(2):430-6. [Medline]

I couldn't find it.

35. Lean ME, James WP. Metabolic effects of isoenergetic nutrient exchange over 24 hours in relation to obesity in women. Int J Obes. 1988;12(1):15-27. [Medline]

Twenty-four hour whole body indirect calorimetry has been used to study the effects of feeding, during a sedentary test day, isoenergetic diets which varied in fat (3 or 40 per cent of total energy) and carbohydrate (82 or 45 per cent) content. Three groups of women were studied: lean, obese and 'post-obese' after slimming. Diets weren't compared at all.

http://www.ncbi.nlm.nih.gov/pubmed/3360561

36. Abbott WG, et al. Energy expenditure in humans: effects of dietary fat and carbohydrate. Am J Physiol. 1990 Feb;258(2 Pt 1):E347-51. [Medline]

A high-dietary fat intake may be an important environmental factor leading to obesity in some people. The mechanism could be either a decrease in energy expenditure and/or an increase in caloric intake. To determine the relative importance of these mechanisms we measured 24-h energy expenditure in a whole body calorimeter in 14 nondiabetic subjects and in six subjects with non-insulin-dependent diabetes mellitus, eating isocaloric, weight-maintenance, high-fat, and high-carbohydrate diets. All subjects were Pima Indians. In nondiabetics, the mean total 24-h energy expenditure was similar (2,436 +/- 103 vs. 2,359 +/- 82 kcal/day) on high-fat and high-carbohydrate diets, respectively. The means for sleeping and resting metabolic rates, thermic effect of food, and spontaneous physical activity were unchanged. Similar results were obtained in the diabetic subjects. In summary, using a whole body calorimeter, we found no evidence of a decrease in 24-h energy expenditure on a high-fat diet compared with a high-carbohydrate diet.
http://www.unboundmedicine.com/evidence/ub/citation/2305878/Energy_expenditure_in_humans:_effects_of_dietary_fat_and_carbohydrate_

37. Yerboeket-van de Venne WP, Westerterp KR. Effects of dietary fat and carbohydrate exchange on human energy metabolism. Appetite. 1996 Jun;26(3):287-300. [Medline]

Short-term effects of low-fat (10% fat energy), mixed (30% fat energy), and high-fat (50% fat energy) diets on 24-h energy expenditure, and on its components sleeping metabolic rate, diet induced thermogenesis and energy expenditure for physical activity were studied for 3 days using a respiration chamber in twelve normal-weight female volunteers classified as restrained or unrestrained eaters. There were no significant differences in any of the four measures between the restrained and unrestrained eating subjects on any of the diets. Within the group of restrained eaters, 24-h energy expenditure was significantly decreased during consumption of the mixed diet (8.21 +/- 0.21 MJ/d; p < 0.01) and tended to be decreased on the high-fat diet (8.22 +/- 0.25 MJ/d; p = 0.055), relative to the low-fat diet (8.58 +/- 0.21 MJ/d). Diet composition had no effect on 24-h energy expenditure in the women with unrestrained eating. The results suggest that a low-fat diet would be beneficial in the treatment of obesity, especially if subjects have a restrained type of eating behaviour. Where are the carbs?

http://www.ncbi.nlm.nih.gov/pubmed/8800484

38. Astrup A, et al. Failure to increase lipid oxidation in response to increasing dietary fat content in formerly obese women. Am J Physiol. 1994 Apr;266(4 Pt 1):E592-9. [Medline]

Decreasing the dietary fat content increased 24-h EE in the postobese women (P = 0.02), whereas it was unaffected in the control group. Independent of energy balance, an increase in dietary fat content to 50% fat energy results in preferential fat storage, impaired suppression of carbohydrate oxidation, and reduction of 24-h EE in postobese women. Is that why low carb diets work so well--obese people have impaired carb oxidation?

http://www.unboundmedicine.com/evidence/ub/citation/8178980/Failure_to_increase_lipid_oxidation_in_response_to_increasing_dietary_fat_content_in_formerly_obese_women_

39. Whitehead JM, McNeill G, Smith JS. The effect of protein intake on 24-h energy expenditure during energy restriction. Int J Obes Relat Metab Disord. 1996 Aug;20(8):727-32. [Medline]

CONCLUSIONS:
Maintaining protein intake reduces the decrease in energy expenditure during energy restriction.
http://www.ncbi.nlm.nih.gov/pubmed/8856395

Notice where it said weight loss was higher, but no metabolic advantage was found, even though they expected one? That's because the extra weight lost on a low carb diet is water, not fat. When you extend studies out to a year, rather than 12 weeks, weight loss is equal, because the loss in water weight catches up in the higher carb group.

Also, your comment on study 38. That study wasn't done on obese women, it was done on healthy weight women, who were obese. Women who gained weight and then lost it. It showed they were more likely to store fat while eating a high fat diet.

Your comment on 35. Did you miss the part of the abstract that said they used 2 different diets, one that was 3% fat, 82% carb, and the other that was 40% fat, 45% carb, (both diets being 15% protein?) And you only posted part of the abstract, so you left out this line: There were no large differences in energy expenditure between the two diets or between the groups but the thermogenic effect of the high carbohydrate diet was significantly greater than that of the high fat diet (5.8 vs 3.5 per cent of energy expenditure: P less than 0.01).
No significant differences in energy expenditure with either diet. I'd say diets were compared.

For your comment on 37, do the math. Protein and calories are constants, when fat is increased or decreased, carbs are changed to compensate.

For study 32, that study essentially says that people on high fat diets eat more, and gain more fat, because humans are much more efficient at oxidizing carbohydrates for energy than fat, so higher fat intake, along with higher calorie intake, leads to more fat storage. From the actual study (you can download it from pubmed:) Our results suggest that HF diets are more obesity producing than are HC diets. This is because there was a greater total energy intake on HF than on HC diets and because humans have a lesser ability to increase fat oxidation in response to increased fat intake than to increase carbohydrate oxidation in response to increased carbohydrate intake.

Also, substrate oxidation is a catchall term for protein, fat, and carbohydrate oxidation. "Burning calories" is oxidation. You burn fat by oxidizing it, same with burning carbs or protein. So saying that "varying substrate oxidation had no effect on total energy expenditure" means that it doesn't matter what combinations of carb, protein, and fat you eat, you will expend the same amount of energy either way.

BUMP FOR LATER

It seems to me that society is always looking for a blame or a reason, rather than accepting people are over eating and not exercising, except for extremely uncommon instances the vast majority of weight gain and obesity is simply too many calories, too much sugar and zero exercise. Common sense dictates that anything in moderation is generally healthy, that would obviously preclude anything unhealthy right, Two examples that I have recently witnessed both I admit are extremes but they remain valid nontheless. I recently had to attend the emergency room for an asthma attack that got out of hand, whilst there a young boy in the next bed was violently ill and in severe abdominal pain. I guess him to be about 7 with two obese parents and he would have been an estimated 60 lbs over weight himself. When asked by the doctors what he had eaten that day his response was, potato chips, and nothing but, except for the coke... Recently whilst shopping for frozen yogourt there was a morbidly obese woman in a motorised scooter buying ice cream by the pail. Granted these are extremes but they indicate the problem with society and overeating. Low carb diets were originally thought good weight loss regimes for severely overweight people, the one main downside is they are difficult to maintain for life. Ever wonder why there is always a new diet craze, it is because we are always looking for an easy way to lose weight. There isn't one, it's by calorie deficit, exercise and hard work. That's why most of us have ended up at this website. If a programme works for you then well and good, but please always check with your doctor, I used to do Atkins until quite my accident I mentioned it to by kidney specialist (only have 1 kidney), he absolutely freaked on me and said it was far too much work on an already overworked kidney, so please always check that is is okay for you.