Starvation Mode - Adaptive Thermogenesis and Weight Loss

This is great! Thanks Evgeni!

Ok, not sure if anyone has already asked this but....

Is there any evidence to support the idea that people who end up obese have more efficient metabolisms to start with than "naturally skinny" people? I would imagine that if you are pre-disposed to a more efficient calorie absorption, you would need fewer calories to maintain, which would make you more likely to gain weight.

The reason I ask is because (anecdotally) everyone has that skinny friend who seems to eat like a horse, does no excercise, but still doesn't put on weight! If there are genuine differences in metabolic efficiency between people, then might that explain the annoying skinniness of those people? Could that also explain the drop in EE after weight-loss?

Anyone know of any research into this?

Thankyou for the informative post! Very interesting especially regarding maintenance TDEE after weight loss. It would be good to see a graph of amount weight lost = final TDEE -x% to maintain.

Thankyou for the informative post! Very interesting especially regarding maintenance TDEE after weight loss. It would be good to see a graph of amount weight lost = final TDEE -x% to maintain.

There isn't a fixed amount of AT and it seems to vary on diet, duration and possibly other factors. A few of the references did have graphs but I'm not going to dig those up now - I'm working on something else.

If you are interested in estimating a potential variation for yourself you can do this by taking one of the standard equations like Ketch-McArdle and graphing it versus weight or bf%. Oh, heck, I'll do one over the next day....

Oh gosh haha I didn't mean for you to go out of your way I was just thinking out loud but if you did that would be awesome! But seriously the info you have already gathered is really fascinating and will help me when I'm back on maintenance to slowly up my cals until I hit correct TDEE instead of bam MFP suggested TDEE (although I didn't really track when I was maintaining and that was the reason I ended up gaining again)

Cheers EvgeniZyntx!

Very, very interesting, thanks heybales. Also I find particularly noteworthy that sedentary TDEE did not drop in the exercise group, despite the fact that no strenght training was used.

Too bad the study lasted only six months, it would be interesting to see the long term effects.

Request to include another study and brief write-up from my blog entry referenced above.

So several studies have pointed to this effect of adaptive thermogenesis, some of which is expected. But found a nice recent one that covered several effects at once nicely.

First, the totally expected part. I'll try not to use the term metabolism as an all day type thing including all activities when that is really TDEE. Metabolism is mainly the lower level functions, some base and required though can be slowed down, some higher level functions like cell replacement for skin, hair, nail, muscle growth which can really be slowed down or skipped, and even higher level stuff like processing foods which probably shouldn't be considered metabolism normally, but some do ("kick start your metabolism by eating breakfast" misunderstanding).

Your TDEE is composed of your BMR (Basal metabolism) + NEAT (Non-Exercise activity) + TEF (energy burned processing food eaten) + EAT (Exercise activity).

If you eat less, your TEF burn (usually about 10% of what you eat) goes down, so TDEE goes down. So eating 2000 TEF is 200 of that, go to eating 1600 TEF is 160, so loss of 40 calories to TDEE, not much.

As you start to weigh less, NEAT and EAT (if pace & intensity kept the same) go down since you are moving less mass around, so TDEE goes down. What may happen though is you move more since you weigh less, and exercise harder. So perhaps no adjustment to TDEE, but probably lowering.

As there is less body mass for functions, the BMR will go down slightly. If mainly fat mass lost, not that bad since it didn't require much energy anyway (2 cal/lb a day). But muscle mass lost, while resting energy use isn't much (6 cal/lb a day), that lost muscle being used daily could impact TDEE badly. Along with less mass is perhaps less LBM which includes blood volume, less muscle is also less glucose stores (with water), and water management is a decent calorie burn too. So as weight goes down, BMR goes down somewhat depending on what is lost, and therefore TDEE will lower too.

So outside all those known and expected reasons for your metabolism and TDEE to burn less as you diet and lose weight, there is the one that could be avoided, and perhaps you want to avoid it to make maintenance easier.

And that is a drop in TDEE unrelated to any of the above, and is just the body getting more efficient with BMR, TEF, NEAT, and EAT altogether, metabolic adaptation is what it's usually called. Sometimes called metabolic damage, if you consider lower than what it was and could be damage, or merely the body doing what it has to do.

Here's the 6 month study in full if you want to dig in to it, I thought I'd point out some tidbits.

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004377

Participants had to be between BMI 25-30, overweight category, but healthy otherwise. They were excluded if they smoked, exercised more than twice a week, were pregnant, lactating or post-menopausal, had a history of obesity (BMI>32), diabetes, cardiovascular disease, eating disorders, psychological disorders, substance abuse or regularly used medications except for birth control. So that may have a bearing in comparison.

Diet was 55 / 15 / 30 for C / P / F.

CR (Calorie Restriction) was 25% deficit from TDEE, so not massive.

CR + EX (EXercise) was 12.5% deficit plus 12.5% calories burned in cardio exercise 5 x week, each session being 403-569 calories for 45-53 min (women and men difference).

LCD (Low Calorie Diet) was 890 cal/day until 15% of weight was loss, then back to maintenance calories by month 3, whatever it was then. That's a tad massive

DEXA scans for body composition of LBM (Fat Free Mass (FFM)) and Fat Mass (FM). Sedentary TDEE measurements in a metabolic chamber for 23 hrs. SMR (Sleeping Metabolic Rate (BMR)) measured chunk of night no movement.

Several formulas related to measured Sedentary TDEE at baseline based on all available stats, to compare down the road when stats changed.

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

At 6 month check, there was some recovery to be had, and reminder the LCD was at maintenance this entire time from 3-6 months...
CR - 209
CREX - 129 over expected
LCD - 275

So notice that even after 3 months maintenance level eating, the initial LCD group still had a TDEE 275 below what was expected for their current LBM and FM. Perhaps more time at maintenance it would have recovered?
The CR group slightly recovered, but still 209 lower than expected.
The CR+EX group actually had an increased TDEE.
Now that was Sedentary TDEE in the lab that was compared.

Daily TDEE with all activity was also compared to their SMR, TDEE/SMR for physical activity rate (PAR).
At month 3, CR and LCD had significant drops in PAR below what would have been expected for their current LBM and FM, by CR 350 and LCD 497, with CR-EX having none. At month 6, CR 215 and LCD 241, so again some recovery.

So the NEAT part of their day decreased as expected because of lower weight, but even more than expected because of less movement, resulting in lowered figures above.

So, that is how much their TDEE dropped along with their lower eating level and weight.

Now imagine during your weight loss, is your TDEE being lower going to help or hinder you for sticking to an eating level? May depend on how little you really want to eat.

They lost in total CR - 8.3, CR-EX - 8.4, LCD - 11.2.
So while the LCD did lose the most (in 3 months too compared to 6), their TDEE had only recovered from 496 to 275 below what it could be, perhaps more recovery was coming. So no wonder the first few months of maintenance could be the hardest, you have the most suppressed metabolism then.

And notice that even the great results of the CR-EX group, still meant 8.4 lbs in 6 months of dieting, with a 25% deficit in essence, 12.5 created by diet, with additional 12.5 by extra exercise. But no loss of TDEE, in fact increase, and mere decent level of cardio.

Other point to keep in mind - no more than 2 x exercise a week was being done prior - so they had a lot of room for improvement. No weight loss prior, so full burning metabolism. And in overweight range, not obese where these effects might not be so bad.

Thought it was interesting info to know. So when you are talking about metabolism slowing down, it's more correctly your TDEE slowing down with all the components of it to some degree, beyond what was going to happen anyway. And recovery to expected levels could be well over 3 months when at maintenance.

Here is another study reference a lot like the one above, this one trying to come up with a formula to take into account this more than expected downgrade in metabolism/TDEE.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2764961/

While strength training was not used in this group, remember that these are individuals where selected so that they did no exercise prior to the eval and, for the period given, walking cycling or running might be considered an initial increase in load and as such, "resistance training".

True, good point. And that is another reason why it would have been nice to have a longer observation period - to be able to establish if there is some sort of adaptation to the cardio workout. I think it would be interesting to see if during a long (1-2 years) period of caloric restriction cardio exercise alone could be enough to contrast the effect of AT.

And the study details don't mention it, but I'd imagine that in 3 months from little to no exercise, to 5 x a week, their VO2max improved decently. Improved fitness level means you can do harder work at same HR, so more calorie burn.

And since they measured calorie burn on treadmill and noted HR that matched what they wanted at the start, then maintained that HR it sounds like through the whole study time, that would actually start causing more calorie burn later as they got more fit.

If so that would mean, the CREX group was likely really burning more calories in exercise in the end than the desired 12.5% of non-exercise TDEE.

How much? Well, slightly less weight to move, so less calories then, but if they maintained HR, more calories then.
It's those unstated things that make you wonder, did they take it in to account and not mention it - or no one thought of those things?

Like my still big question I didn't see stated one way or another, after they got more accurate TDEE figures at 3 months, did they adjust the 25% and 12.5% based on new tested TDEE, or the original TDEE? The LCD that went to maintenance sounds like they started eating at that new TDEE found.

If the original, I'm wondering how bad would the adaptation have been if they had basically chased the adapted TDEE lower, would there have been that slight recovery, the same lowered amount, or even worse?
If the new tested TDEE, and it still recovered a tad like it did, that would speak well to finally getting a full recovery to what is expected.

I should probably read this..to my feed.

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This is the probably the single most informative, well researched discussion and article I've stumbled across in 18 months. I can't thank you enough for taking the time to research and post this information.

I started a massive weight loss journey in 2010. I was over 350 lbs and 40% body fat. The first 18 months were one success after the other. At one point I had lost 93 pounds and was at 24% body fat. Then I plateaued. The last 18 months I have been on that plateau. Last year I tried several extreme nutrition changes to break this plateau (paleo, low carb, low cal, high cal) and over a 3 month period from March to May a certified nutritionist put me on an 1800/day plan with minimal protein intake and I gained almost 20 lbs as a result. I've struggled physically, mentally and emotionally with the stalled progress and this post gives me hope. I rededicated myself in January and set my intake to my BMR with a focus on protein and will know the results of this first month on Saturday. Without knowing it I may have started what will be a prefect real-world test of several of these theories, with 3 years of measured data to support the results. I have considered through my own observations that there are limits on the amount of fatty acids that can be metabolized and this discussion has given credence to those observations. I have often discussed with my best friend, an doctor, that there MUST be something larger at play for a man who has lost a substantial amount of weight versus a man who has just started, that my body is coping with physiological changes now that weren't in play during the first 18 months. I can't believe that I found this post today, and the knowledge it has given me.

Thank you again.

Would some of you say that adaptive thermogenesis affects teenagers?

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Holy Science Batman. I love this stuff.

psulemon


How is it that you've just found this thread? :laugh: