The FastDay Forum

Is it due solely to lower weight or is there more to it, and if so what?

This topic has come up a few times lately in other threads, for example re: plateaus. As we lose weight our TDEE drops. We weigh less, so we burn fewer calories moving around. But, some research suggests that as we lose weight, our TDEE drops below what would be due to weight loss alone.

I've linked to this article in the NYTimes a few times: http://www.nytimes.com/2012/01/01/magaz ... wanted=all

and a link to the actual publication: http://www.nejm.org/doi/full/10.1056/NEJMoa1105816

Is this phenomenon the same as "famine reaction", "starvation mode", "set point" and various other phrases kicking around? Is it possible that part or all of this additional (beyond what lower weight alone causes) lowering of TDEE is due to loss of muscle, which has much higher metabolic activity than fat, an idea I originally found on Krista Varady's EOD Facebook page, which unfortunately didn't give a reference.

I'm not as up on the literature as @carorees; I'm more likely to pick things up from popular science sources like the NYTimes "Health" pages.

I thought this topic deserved a thread of its own. I'm curious what other people think, or what other research people have come across.

BTW, I just calculated the difference in my TDEE from when I started this WOE vs. now (based on a calculator--so predicted TDEE not necessarily my real TDEE): almost 300 cals! I am wondering if this alone can explain my weight loss slowing down. I'm using MFP now, so I should be able to make a better calculation at my real TDEE soon.

I guess I'm also wondering whether IF will get around this problem: is it weigh loss per se that causes it or prolonged calorie restriction? If the muscle theory explains it all, if there is hardly any muscle loss with IF, perhaps it won't be a problem? It has been shown (I think) that muscle loss is reduces with AFD vs. CR. But I don't know whether the hormonal changes have been measured in this context, and certainly after 1 yr of maintenance as in the NEJM publication.

Hi:

TDEE is a mystery to me.

On Dr. M's exercise program on the BBC an expert he interviewed just laughed at the various exercise equipment's add ons that purported to measure calories burned. It seems every body is different, from muscle mass to metabolism.

The various TDEE calculators I've seen only account for age, height, weight, gender and physical activity. Muscle mass is not a variable, which has always led me to question the claim that muscle mass increases metabolism. When you play with the formulas (just input different info, like weight) you will find that sometimes as weight falls TDEE rises.

That's why when I run into someone who says they are doing diet days properly and eating to their TDEE and still not losing weight, I simply respond that they need to eat less to lose weight - the TDEE they calculated is wrong for them.

Without the fancy equipment used to accurately measure TDEE that measures exhaled breath, all calculations are estimations that should be modified if the facts don't match expectations when it comes to weight loss.

Always the pragmatist, @simcoeluv

sure, calculated TDEE (for which there isn't a single value anyway, given the number of different calculators out there) and "real" TDEE can be different. I'm trying to get at the reasons why, especially the increase in this difference that happens with weight loss.

At the end of the day, though, you're right: to maintain weight (or to keep losing weight, if that's your goal) you need to eat based on your "real" TDEE, however different it happens to be from what you calculated. I was surprised by the 300cal difference just based on weight loss along predicted by the MifflinStJeor equation for TDEE. I had done this calculation awhile back but had forgotten about it. Now that I am tracking my calories with MFP, I can see that I am overeating on some non-fast days, though so far not by more than 300 cals. It seems my body's idea of "normal" eating is still adjusted for my old weight, even though I had gotten the impression my appetite had gone down with this WOE.

I wonder if this research group (or another group) plans to do a similar study on people who lost weight by different means. That would be cool.

Hi:

I've posted this before, but if you want to see an example of different metabolisms and how they work (and why there may not be one answer to TDEE questions), this is a must see: http://topdocumentaryfilms.com/why-are- ... e-not-fat/

I just noticed this response to a question on Krista Varady's Facebook page. I will look around for the refs…

"Should one keep their calories up on feast days in order for metabolism to not slow down?"

Unfortunately, all weight loss diets lower your metabolism by 10-15% when you reduce your body weight by 10% or more. This occurs with both daily calorie restriction and intermittent fasting. The only way to prevent this drop in metabolic rate is to exercise 5 times per week for 45 min/session (which increases your muscle mass). Since your muscle mass is a key determinant of your metabolic rate, increasing muscle mass will ensure your metabolism stays high, even post-weight loss. Hope this helps!

Thanks for that input, @kencc

I'm currently trying to reduce bf%, since, if my scales are correct, it's still shockingly high in spite of the weight loss. At this point for me, it's a more important goal than losing any more weight, though the two may go together.

OMG I'm so excited. It has a name: adaptive thermogenesis. And I've found loads of references. I will report back with links in case anyone is interested.

edit to add:
so there's this blog post: http://www.myfitnesspal.com/topics/show ... eight-loss
which refers to this review: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673773/

[carorees]

@MaryAnn Thanks for posting this link...what a great review paper!

One thing that is not mentioned in the paper is the potential link between lowered TDEE and longevity. There is a school of thought that the reason why the CRON (calorie restricted optimal nutrition) protocols may have led to prolonged life in animal studies is because their metabolic rate may have been reduced. So rather than attempt to fight the reduction in TDEE, perhaps we should embrace it?

Here are some interesting papers on calorie restriction and longevity:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000242/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278796/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2253665/

Another thought regarding the weight regain problem, is that lowered leptin levels which occur with dieting increase appetite and may contribute to the weight regain (as detailed in the review paper), but intermittent fasting (specifically Ramadan fasting) has been shown to increase leptin levels: http://apjcn.nhri.org.tw/server/APJCN/12/4/483.pdf What is interesting about this paper is that the participants studied ate about the same or slightly more calories during Ramadan than before yet their weight either stayed the same or decreased while their leptin levels increased.
Generally the month of Ramadan involves a nightly feast following the daytime fast, at which food is often high fat (http://www.ncbi.nlm.nih.gov/pubmed/17193859) so of course it might be the change to a higher fat diet as well or instead of the fasting that increased leptin.

Thanks for linking to these very interesting articles.

Pulling a sentence out of the NYT article "Studies suggest that even a 5 percent weight loss can lower a person’s risk for diabetes, heart disease and other health problems associated with obesity." I've often heard this said, and wondered if the improvement in the risk factors is due to the very hormonal changes that then push us to regain the weight. So while the 250 pound woman of their example is fighting her urges and maintaining her loss, or continuing to lose, her health benefits remain. But perhaps if she maintains long enough that her hormones re-set, ie the 95% weight is her new normal and she doesn't struggle to maintain any more, then maybe the health benefits disappear - since 5% isn't much of a change for a very fat person. And in the case that she falls off the wagon and ends up heavier than she started, she must surely be even worse off for risk factors.

Do you know if there are any studies which show a long-term improvement in risk factors? Or are the results, as I suspect, based on measures at the end of a 6 week or 12 week diet study, while the subjects' bodies are still in dieting mode?

Thanks for this thread @MaryAnn - the topic is well worth space of its own (I keep posting those links too!).

Anyone able to get their mitts on this? Looks mighty interesting and is slightly more recent...

"Adaptive thermogenesis in human body weight regulation: more of a concept than a measurable entity?"

http://www.ncbi.nlm.nih.gov/pubmed/23107264

And for those who'd like an easier read (myself included when it comes to new concepts initially), I thought this was a stonker:

http://www.burnthefatblog.com/archives/ ... isited.php

Cheers, FatDog

[carorees]

I thought this was a stonker:

http://www.burnthefatblog.com/archives/ ... isited.php

Cheers, @FatDog

I mis-read the last link as "burntheFatDog.com" !!!

[carorees]

I've been reading a bit lately about the science behind how our bodies change as we lose weight, in particular what happens to the number of calories we use (TDEE). Several studies have found that TDEE declines more following weight loss than would be predicted by the TDEE calculation formulas (such as used by the progress tracker).

This is a subject that has been much debated. The recent paper Adaptive Thermogenesis in Humans by Michael Rosenbaum and Rudolph L. Leibel http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673773/ tries to cut through what is known. Much of the debate surrounds whether the lower energy expenditure is due to fundamental changes in our metabolic rate or whether it is down to becoming more lethargic (i.e., sleeping more, wriggling less).

To my mind, it doesn't much matter exactly how much of the change in TDEE is due to us being smaller, a change in metabolic rate or not wriggling so much, but what does matter is that we are aware that our TDEE might actually be less than we think.

Rosenbaum and Leibel say:

Maintenance of a 10% or greater reduction in body weight in lean or obese individuals is accompanied by an approximate 20%-25% decline in 24-hour energy expenditure. This decrease in weight maintenance calories is 10–15% below what is predicted solely on the basis of alterations in fat and lean mass. Thus, a formerly obese individual will require ~300–400 fewer calories per day to maintain the same body weight and physical activity level as a never-obese individual of the same body weight and composition...the reduction in twenty four hour energy expenditure (TEE) persists in subjects who have sustained weight loss for extended periods of time (6 months – 7 years)...

I am thinking that this is really really important.

I have lost considerably more than 10% of my body weight: more like 35%. According to the TDEE calculators my (sedentary) TDEE has gone down from 1924 cals/day to 1524 cals/day, but if I add an extra 10-15% reduction, that would be around 1300 cals/day. Over 200 cals less than the progress tracker is telling me.

I wonder if some people who have lost weight only to have plateaued are suffering from this problem and assuming that their TDEE is higher than it actually is. Might it be worth thinking about your calorie needs as potentially being less than the progress tracker says?

Also, consider your final goal. If your daily calorie needs are going to be so much lower at your target weight than currently, can you keep eating that way for 7 years (or more) in order to maintain that loss? If not, perhaps you should not set a weight loss goal so much as set a TDEE you can stick to and see what weight you end up at!

Thank you for this @carorees...I was talking to my husband about this very same thing yesterday (i.e. the amount of food we might need on a daily basis when we reach our goal weights) and we've decided that we will need to continue this WOE for a very, very long time...probably for the rest of our lives. Your post has confirmed that we WILL in deed have to carry on with a reduced intake as neither of us wish to return to our old overweight selves.
I am here for the long term that's for sure.

Sounds like that might be one reason why it's so easy to put the weight back on when you come off a diet and start eating 'normally'. If you need less calories that a 'never overweight' person does for a similar weight and activity level you might think you are being good, but you're still overeating.

Hmmm...very interesting!