Advanced calorie deficits (Fair Warning - long post)
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Tagging post.
Would be really nice to see this in a sticky somewhere... Or may be added to the "links on MFP you want to reread"? For geeky noobs like me, that's the kind of info I am looking for.0 -
Bump0
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Glucose and ketones are the brains preferred fuels, but fat is the preferred fuel of muscle especially in aerobic conditions. This is why your liver converts all excess carbs via into fatty acids for storage.
This is kinda true. I say that because when muscle is in a resting state, there's a balance between glycogen and FFA usage depending on serum glucose levels in the body, low serum levels means more glycogen usage. I can't speak to whether that's the reason why the body converts energy into FFA's, I've never read any studies postulating that before. To me it was just common sense, the body will use the most efficient storage path, with 9 calories per g for lipids vs 4 (+-) for carbohydrates, it's just reasonable to assume it will use the most efficient storage method. Whether that's accurate, I don't know. But if you have some studies or research that shows evidence of reasoning for conversion to lipids, I would truely like to read it.
I'm not being snarky at all, I mean it, I would like to read any information you have.
I make no bones about my own knowledge level, there's plenty I don't know, even after studying this stuff for many years. I'm always willing to learn more, and not afraid to say when I'm mistaken or misinformed about something.
Actually the whole explanation of fat metabolism was off as well. Triglycerides have a glycerol backbone. When the fats are being metabolized they are not converted to glucose. The fat is burned and then the glycerol backbone is released from the triglyceride and it is converted to glucose for storage as glycogen, release to the blood, or immediate consumption depending on the situation. You are correct that glucose is burned when blood serum glucose levels are high. However, I would consider this more of a disposal mechanism that a normal state of metabolism as your body does everything it can to quickly return blood glucose levels to normal after eating carbs. The preferred fuel for the body is fat and only during intense periods of exercise do your muscles rely on glycogen.
Two questions:
1. What do you mean when you say "fat is burned"?
2. When talking about preferred fuel, you mention glycogen, but from what I have read, glucose is the fuel we are talking about for preference (versus fat and ketones). Does the formula still hold for glucose vs. fat/ketones? Maybe my understanding about glucose --> glycogen or glycogen --> glucose is wrong.
When I say fat is "burned" I really mean metabolized.
I used glucose and glycogen interchangeably. However, during periods of intense exercise my understanding states that muscles will draw down stored glycogen stores and pull from blood glucose for energy. Your liver will try to maintain blood glucose levels and also generate ketones depending on liver stores of glycogen (which are relatively small). Glycogen is released in your muscles as glucose when needed. You muscles in aerobic conditions will tend to metabolize fat over glucose and this is greatly affected by dietary choices. However, fat metabolization is preferable for many reasons.0 -
Bump for later0
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Thanks- I plan to read these and comment when I have more time this weekend. It takes some time to look at exactly what they are saying, what they did, what controls were done, etc, and what it has to do with the concept of a "starvation mode."
First glance- from the article in heybales's post- the numbers posted regarding a drop in energy expended beyond that expected are TDEE, not basal metabolic rate, which I think is what people generally mean when they talk about a drop in "metabolism." Looks like they are saying people who were on low calorie diets (without exercise) ended up with the "behavioral adaptation" of moving less throughout the day. In fig 4, they show the drop in metabolic rate (measured during sleep) in Cal/day before and after caloric restriction was a more modest ~130 Calories/day, and this number does not account for changes in weight and body composition. Also the group on a lower calorie diet lost more weight total (fig 2). But... I didn't read the whole thing yet, just looked at the figures. Thanks for posting.
Any researchers in this field care to chime in?0 -
Thank you for sharing your knowledge. The article content is thought provoking and a boost to help me on my health journey.0
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Thanks- I plan to read these and comment when I have more time this weekend. It takes some time to look at exactly what they are saying, what they did, what controls were done, etc, and what it has to do with the concept of a "starvation mode."
First glance- from the article in heybales's post- the numbers posted regarding a drop in energy expended beyond that expected are TDEE, not basal metabolic rate, which I think is what people generally mean when they talk about a drop in "metabolism." Looks like they are saying people who were on low calorie diets (without exercise) ended up with the "behavioral adaptation" of moving less throughout the day. In fig 4, they show the drop in metabolic rate (measured during sleep) in Cal/day before and after caloric restriction was a more modest ~130 Calories/day, and this number does not account for changes in weight and body composition. Also the group on a lower calorie diet lost more weight total (fig 2). But... I didn't read the whole thing yet, just looked at the figures. Thanks for posting.
Any researchers in this field care to chime in?
In many of the studies that I posted, you will see that there is a drop in the RMR after about 72 hours (after an initial minor increase in energy which is postulated to be because of the energy needed to convert fat stores), which continues throughout the starvation period and underfeeding periods (depending on which study you are looking at). Most talk about the depletion of glycogen reserves and the transition to a lower level of insulin production0 -
Thanks- I plan to read these and comment when I have more time this weekend. It takes some time to look at exactly what they are saying, what they did, what controls were done, etc, and what it has to do with the concept of a "starvation mode."
First glance- from the article in heybales's post- the numbers posted regarding a drop in energy expended beyond that expected are TDEE, not basal metabolic rate, which I think is what people generally mean when they talk about a drop in "metabolism." Looks like they are saying people who were on low calorie diets (without exercise) ended up with the "behavioral adaptation" of moving less throughout the day. In fig 4, they show the drop in metabolic rate (measured during sleep) in Cal/day before and after caloric restriction was a more modest ~130 Calories/day, and this number does not account for changes in weight and body composition. Also the group on a lower calorie diet lost more weight total (fig 2). But... I didn't read the whole thing yet, just looked at the figures. Thanks for posting.
Any researchers in this field care to chime in?
That's not how I'm interpreting it. If you read the discussion, they clearly (in the second paragraph) state that they observed a real metabolic adaptation even after TDEE was adjusted for the lower metabolic rates of reduced FFM and FM.
here's the quote from the part I am talking about:
"Now for the first time, we objectively characterized the response in all the components of daily energy expenditure to caloric restriction by combining doubly labeled water and indirect calorimetry (Figure 4). In response to caloric restriction (CR/LCD) we observed a true metabolic adaptation at months 3 and 6 of the intervention. To exclude the contribution of sedentary energy expenditure (the largest component of daily energy expenditure), we adjusted TDEE for sedentary energy expenditure (24h-EE and SMR) and observed that measured TDEE was significantly less than predicted at both month 3 and month 6 of CR. Interestingly no metabolic adaptation was observed in CR+EX. Together, this data indicates that TDEE is reduced with caloric restriction and is likely the result of a metabolic adaptation in the sedentary state accompanied by a reduction in activity-related energy expenditure and reduced levels of physical activity (Figure 3). Therefore, this study supports a ‘metabolic adaptation’ in response to weight loss in humans and demonstrates for the first time a reduction in all components of daily energy expenditure with dietary-induced weight loss, including the level physical activity. Importantly, CR in combination with exercise (CR+EX) did not result in metabolic adaptation while inducing similar changes in body composition as with CR alone."
for the record, even though this is a much longer term study then the ones I posted, most of the data correlates with some minor variation. I especcially love the study done by MacDonald and Webber called Feeding, fasting and starvation: factors affecting fuel utilization. I believe it's the first link I posted, it's the one that goes to cambridge.org0 -
You wrote "The less fat you have the more difficult it is to keep a deficit"
I'm not sure what you are trying to say there. First off, the three energy systems are in constant use, lipid oxidation is a permanent process, it's use, in terms of energy availability varies but it is still always present. Fat is constant being liberated and free plasma fatty acids are sufficient for exercise needs in excess of hours in the non- fasting individual. While fat does have a metabolic cost, to release it's incorrect to think of it in terms of an energy cost but rather a enzymatic/conversion rate cost. You can only deliver so much free FA at any time.
If anything, the less LBM you have, the more difficult it is to keep a deficit.0 -
Glucose and ketones are the brains preferred fuels, but fat is the preferred fuel of muscle especially in aerobic conditions. This is why your liver converts all excess carbs via into fatty acids for storage.
This is kinda true. I say that because when muscle is in a resting state, there's a balance between glycogen and FFA usage depending on serum glucose levels in the body, low serum levels means more glycogen usage. I can't speak to whether that's the reason why the body converts energy into FFA's, I've never read any studies postulating that before. To me it was just common sense, the body will use the most efficient storage path, with 9 calories per g for lipids vs 4 (+-) for carbohydrates, it's just reasonable to assume it will use the most efficient storage method. Whether that's accurate, I don't know. But if you have some studies or research that shows evidence of reasoning for conversion to lipids, I would truely like to read it.
I'm not being snarky at all, I mean it, I would like to read any information you have.
I make no bones about my own knowledge level, there's plenty I don't know, even after studying this stuff for many years. I'm always willing to learn more, and not afraid to say when I'm mistaken or misinformed about something.
Actually the whole explanation of fat metabolism was off as well. Triglycerides have a glycerol backbone. When the fats are being metabolized they are not converted to glucose. The fat is burned and then the glycerol backbone is released from the triglyceride and it is converted to glucose for storage as glycogen, release to the blood, or immediate consumption depending on the situation. You are correct that glucose is burned when blood serum glucose levels are high. However, I would consider this more of a disposal mechanism that a normal state of metabolism as your body does everything it can to quickly return blood glucose levels to normal after eating carbs. The preferred fuel for the body is fat and only during intense periods of exercise do your muscles rely on glycogen.
Two questions:
1. What do you mean when you say "fat is burned"?
2. When talking about preferred fuel, you mention glycogen, but from what I have read, glucose is the fuel we are talking about for preference (versus fat and ketones). Does the formula still hold for glucose vs. fat/ketones? Maybe my understanding about glucose --> glycogen or glycogen --> glucose is wrong.
When I say fat is "burned" I really mean metabolized.
I used glucose and glycogen interchangeably. However, during periods of intense exercise my understanding states that muscles will draw down stored glycogen stores and pull from blood glucose for energy. Your liver will try to maintain blood glucose levels and also generate ketones depending on liver stores of glycogen (which are relatively small). Glycogen is released in your muscles as glucose when needed. You muscles in aerobic conditions will tend to metabolize fat over glucose and this is greatly affected by dietary choices. However, fat metabolization is preferable for many reasons.
Liver stores of glycogen are not small. It about 10-15 percent of total organ weight and really, along with plasma stores, the primary source for non-muscle organs.0 -
When I say fat is "burned" I really mean metabolized.
I used glucose and glycogen interchangeably. However, during periods of intense exercise my understanding states that muscles will draw down stored glycogen stores and pull from blood glucose for energy. Your liver will try to maintain blood glucose levels and also generate ketones depending on liver stores of glycogen (which are relatively small). Glycogen is released in your muscles as glucose when needed. You muscles in aerobic conditions will tend to metabolize fat over glucose and this is greatly affected by dietary choices. However, fat metabolization is preferable for many reasons.
Liver stores of glycogen are not small. It about 10-15 percent of total organ weight and really, along with plasma stores, the primary source for non-muscle organs.
I believe I've normally seen mentioned 400-500 calories worth, sound right?
Even compared to what your muscles in total could be holding, again usually seen referenced 1000-2000 total body, it's not a small % either.
I think it's interesting that if you look at VO2 test graphs for athletes, new, recreational, and pros, the point that fat metabolism in aerobic exercise drops to 50% isn't that high in the span up to lactate threshold, certainly not max HR. Unless you look at endurance athletes, the long endurance guys.
While it may be preferable or desired by the one carrying the fat, I'd say the intensity that most exercise at is well beyond it being preferred. And that preferred state only really improves with some specific training, which many aren't about to do because it's not good for weight loss (fat-burning myth) - too slow for the time taken.
Along with this, the final ratio of fat to carb as energy source is only reached after about 30 min, unless you start out fasted and lower intensity. While many do the former of fasted, they likely don't do the latter of easy cardio.0 -
When I say fat is "burned" I really mean metabolized.
I used glucose and glycogen interchangeably. However, during periods of intense exercise my understanding states that muscles will draw down stored glycogen stores and pull from blood glucose for energy. Your liver will try to maintain blood glucose levels and also generate ketones depending on liver stores of glycogen (which are relatively small). Glycogen is released in your muscles as glucose when needed. You muscles in aerobic conditions will tend to metabolize fat over glucose and this is greatly affected by dietary choices. However, fat metabolization is preferable for many reasons.
Liver stores of glycogen are not small. It about 10-15 percent of total organ weight and really, along with plasma stores, the primary source for non-muscle organs.
I believe I've normally seen mentioned 400-500 calories worth, sound right?
Even compared to what your muscles in total could be holding, again usually seen referenced 1000-2000 total body, it's not a small % either.
I think it's interesting that if you look at VO2 test graphs for athletes, new, recreational, and pros, the point that fat metabolism in aerobic exercise drops to 50% isn't that high in the span up to lactate threshold, certainly not max HR. Unless you look at endurance athletes, the long endurance guys.
While it may be preferable or desired by the one carrying the fat, I'd say the intensity that most exercise at is well beyond it being preferred. And that preferred state only really improves with some specific training, which many aren't about to do because it's not good for weight loss (fat-burning myth) - too slow for the time taken.
Along with this, the final ratio of fat to carb as energy source is only reached after about 30 min, unless you start out fasted and lower intensity. While many do the former of fasted, they likely don't do the latter of easy cardio.
400-600 sounds about right from back of envelope calculation (liver is 1.3-1.5 kg, male, adult, healthy and glucose @ 4 cals/g).
And yes, I agree with Bales and see issues with the bold stated above, while fat use might be preferable it just does not happen alone, for most people.
There are really two places where one can get 80%-90% energy use from fat: at rest or at very high duration of low intensity activity (upon muscular depletion of glycogen). But in reality, it's academic. What you use up in exercise is rebalanced from available substrates and various studies have shown that long-term, for the average person, it doesn't really matter.
Muscle will NOT tend to metabolize fat over glucose in aerobic conditions. It really depends on intensity and duration for any exercise activity that has general duration (say a 20 min run, a zumba class) these will be around half and half. Increase the intensity and one burns more carbohydrates, decrease the intensity and one burns more fat (as a percent of total burn, but less burn overall - also known as: fat burning zone myth). At very long duration of exercise, we can consider fat metabolism to increase significantly but who is running maximal marathons weekly? (Yeah, those long endurance guys, bales mentions).
I'd like to know what the OP means by "greatly affected by diatery choices". Can of worms territory, right there.
(...and a nagging voice in my head says - keep it simple - exercise for fitness, not fat burn. Eat at a deficit and balanced for weightloss. Assure variety and macros for performance.)0 -
In to refer back to, thanks!0
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All good debate folks thanks.
I'm hoping to stay on track here. While the individual talking points of energy usage are important, lets all remember we're talking about functional calorie deficits not theoretical burn rates.
By that I mean, while it's important to know how some of the individual processes work as a function of the whole (by that I mean our TDEE). I'd hope we try to keep in mind that in the end, at least in this conversation, we're discussing ways to keep a calorie deficit without causing undo issues to the person in question or to make it harder to lose fat for that person.
I don't want to get to bogged down in the weeds.
To that end I'll ask this question: Any trainers or nutriton professionals on this thread? Thoughts on practical applications or past client experiences?
I can tell you that myself, as a trainer, I've turned around 2 different people by simply changing their routine and pointing them to RD's when I listened to their current thought processes and diet. One person was seeing a nutritionist that had literally no credentials and was advising all kinds of odd dietary restrictions such as no lactose (even though the person was not lactose intolerent), no gluten (again no signs of crohn's disease or any type of wheat allergies that I could see from talking to them), and was on a strict, low intensity program of walking with some light running and the elliptical, and was at 1200 calories. I urged her to see a RD, she did, and I gave her 1 day of higher intensity cardio, 1 day of HIIT training, and 2 days of weight training along with her 2 days of light cardio and after less than a month, she was happier, had more energy, and had lost 6 lbs with a 4% reduction in Fat Mass (we had done bod pod testing at the start of the session upon my request and again at the 1 month mark). She was ecstatic as she hadn't lost weight in over a month before that point. She also looked much better and was down a full size in her clothes. At no point did I give her diet recommendations other than to see a QUALIFIED professional. I hate when trainers start giving advice to clients under the guise (intentionally or not) of being an expert in the field, unless they truely are an expert in the field.0 -
nvm.
But since there were a few questions on startvation mode and AT, I'll just suggest this thread:
http://www.myfitnesspal.com/topics/show/1077746-starvation-mode-adaptive-thermogenesis-and-weight-loss0 -
interesting read0
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All good debate folks thanks.
I'm hoping to stay on track here. While the individual talking points of energy usage are important, lets all remember we're talking about functional calorie deficits not theoretical burn rates.
By that I mean, while it's important to know how some of the individual processes work as a function of the whole (by that I mean our TDEE). I'd hope we try to keep in mind that in the end, at least in this conversation, we're discussing ways to keep a calorie deficit without causing undo issues to the person in question or to make it harder to lose fat for that person.
I don't want to get to bogged down in the weeds.
To that end I'll ask this question: Any trainers or nutriton professionals on this thread? Thoughts on practical applications or past client experiences?
I can tell you that myself, as a trainer, I've turned around 2 different people by simply changing their routine and pointing them to RD's when I listened to their current thought processes and diet. One person was seeing a nutritionist that had literally no credentials and was advising all kinds of odd dietary restrictions such as no lactose (even though the person was not lactose intolerent), no gluten (again no signs of crohn's disease or any type of wheat allergies that I could see from talking to them), and was on a strict, low intensity program of walking with some light running and the elliptical, and was at 1200 calories. I urged her to see a RD, she did, and I gave her 1 day of higher intensity cardio, 1 day of HIIT training, and 2 days of weight training along with her 2 days of light cardio and after less than a month, she was happier, had more energy, and had lost 6 lbs with a 4% reduction in Fat Mass (we had done bod pod testing at the start of the session upon my request and again at the 1 month mark). She was ecstatic as she hadn't lost weight in over a month before that point. She also looked much better and was down a full size in her clothes. At no point did I give her diet recommendations other than to see a QUALIFIED professional. I hate when trainers start giving advice to clients under the guise (intentionally or not) of being an expert in the field, unless they truely are an expert in the field.
Agree.
I think couple of us just wanting to talk to claims of energy sources used. But really, doesn't matter as you mentioned to a balanced reasonable approach.
As your example shows - higher carb burn activity gave great results, but still some recovery cardio, post meal glucose replacement happens faster, back to normal fat burning state faster. All had great results.
Those general recommendations always seem to be fine, unless there is real food allergy or sensitivities not figured out yet - unduly stressing the body.
I've talked to most of the trainers at the gym, just friendly banter discussions, so I've picked up on many of their personal choices regarding diet. And when I overhear them talking to their clients - it's coming out. Unnecessary advice and all.
Shoot, our spin bike instructor started peppering his post class comments about what to eat that night with his recent conversion to Paleo, because of some guys he runs with. And giving advice on diet in general - no numbers thank goodness.
And his fitness knowledge is already really lacking - "lets stay below 80% HRmax for this session so we burn all stored-fat, we don't want to go above 80% and start burning carbs you ate for breakfast and lunch" - never mind it 6pm class at this point.
Ugh.0 -
Agree.
I think couple of us just wanting to talk to claims of energy sources used. But really, doesn't matter as you mentioned to a balanced reasonable approach.
As your example shows - higher carb burn activity gave great results, but still some recovery cardio, post meal glucose replacement happens faster, back to normal fat burning state faster. All had great results.
Those general recommendations always seem to be fine, unless there is real food allergy or sensitivities not figured out yet - unduly stressing the body.
I've talked to most of the trainers at the gym, just friendly banter discussions, so I've picked up on many of their personal choices regarding diet. And when I overhear them talking to their clients - it's coming out. Unnecessary advice and all.
Shoot, our spin bike instructor started peppering his post class comments about what to eat that night with his recent conversion to Paleo, because of some guys he runs with. And giving advice on diet in general - no numbers thank goodness.
And his fitness knowledge is already really lacking - "lets stay below 80% HRmax for this session so we burn all stored-fat, we don't want to go above 80% and start burning carbs you ate for breakfast and lunch" - never mind it 6pm class at this point.
Ugh.
Ugh, no he didn't! Seriously with the below 80% stuff? I am fine with trainers giving out advice on food types as long as they either have (at a bare minimum) taken and passed nutrition certifications, and/or they at least preface it by saying that they are not a nutrition expert, and if someone really wants to tweak their diet to go see a qualified professional.
I mean, I've spent 7 years reading studies and completing a masters level course in "advanced nutrition and human metabolism" and I still preface advice with the "I'm not an expert" phrase. Even my GP doctor (who's a very good doctor, I got lucky with this guy" makes that statement before we chat about food. He knows I do training and do a lot of research and we trade ideas once in a while, but he always refers me to their RD in the end if I have more in-depth questions.0 -
So as not to "hijack" this one, I started a new thread about scientific experiments related specifically to "starvation mode" with responses to some of those papers above (I didn't have time to get through all of them yet).
http://www.myfitnesspal.com/topics/show/1192992-scientific-basis-of-starvation-mode
Feel free to post more studies there.0 -
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004377
At 3 month check, sedentary TDEE had dropped by the following amounts, below what the formulas would have indicated for new measured LBM and FM, and SMR. In other words, it lowered the expected amount, and an additional...
CR - 371
CREX - 2
LCD - 496
I'm not a big fan of the way they use their own small sample correlations for TDEE at baseline for the subsequent projections of "expected" TDEE etc. Hall has done this in papers and ends up with lines that are quite different in gradient to the "standard" large population correlations.
When you look at TDEE = 1630+33.4(FFM in kg) +1.9(FM in kg) for example in the above reference (I missed off age and gender terms as they are constant) and compare with say Katch-McArdle BMR = 370 + (21.6 x Lean Body Mass(kg) ) the sensitivity to FFM is much higher in their TDEE equation - a multiplier of 1.54 which is more than the TDEE/BMR activity ratio.0
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