Metabolism has changed, must eat 20% less...

brower47

Just finished watching "Weight of the Nation", an HBO miniseries documentary. It was interesting but I found myself squinting at the screen and pursing my lips at several of the points made. This is the one that stuck with me the most.

Quote from the series:

"Did you know that once you lose weight, you have to eat 20% less than a person who weighs the same but has never been overweight to maintain your weight loss. Why? Because your metabolism has changed. This is a fundamental reason why most people regain weight after losing it."

This sounds sketchy to me. Does anyone have any thoughts about this claim?

Francl27

I can see that. I just don't think it's necessary true for all cases. If you lose weight at TDEE-20%, for example, you'll be fine at TDEE. I you lose weight at TDEE-35% or something (looking at you, 1200 calories eaters), your metabolism will be shot and you'll probably gain it all back once you start eating more again... and more. Speaking from experience.

brower47

I can see that. I just don't think it's necessary true for all cases. If you lose weight at TDEE-20%, for example, you'll be fine at TDEE. I you lose weight at TDEE-35% or something (looking at you, 1200 calories eaters), your metabolism will be shot and you'll probably gain it all back once you start eating more again... and more. Speaking from experience.

What bothered me about it was that they said the effect lasts for life. So no matter what you do, you will always have to eat 20% less or exercise 20% more than your hypothetical identical twin that never became overweight in the first place.

If it's true, it's a bit depressing.

bcattoes

I've read many conflicting articles on this. I don't think there is any proof of it, but there is probably enough evidence to make it a controversial subject. I don't think I've ever lost a significant enough amount of weight to say if it personally seems true or not.

But, you could always just burn 20% more calories and eat the same.

eep223

I could see saying you have to eat less because your weight has changed... is that what they mean? I mean, a smaller body uses fewer calories. I suppose in some sense that means your "metabolism has changed." But yeah, if you eat at TDEE, you should be fine. [Your TDEE is lower than it was when you were a heavier weight, though.]

brower47

I could see saying you have to eat less because your weight has changed... is that what they mean? I mean, a smaller body uses fewer calories. I suppose in some sense that means your "metabolism has changed." But yeah, if you eat at TDEE, you should be fine. [Your TDEE is lower than it was when you were a heavier weight, though.]

They way they made it seem was that if you had an identical twin and over the course of several years, you became overweight/obese while your twin remained at a healthy weight, THEN you lost the weight, if the two of you sat down to a meal, she could eat 20% more than you if you were both ate at maintenance. So they are basically saying that once you become overweight, your metabolism will slow by 20% for the rest of your life.

I personally don't put much stock in it even though it was presented as undeniable fact in the documentary.

cwolfman13

Your metabolism is very much adaptable...it is always striving to maintain weight. Of course, we can override this by vastly over or under eating, but ultimately our metabolism will adjust to the new calorie intake and become either more efficient or less efficient.

As an example, while I was eating 2150 gross calories per day while I was losing...by the time I got around to hitting my goal weight, I was pretty much maintaining at that level...where before I was losing 1 - 1.5 Lbs per week. I thought exactly what that show says happens, happened. I sat there at around 2150 gross and just maintained. I decided to very slowly up my calories just to see what would happen...I did this over the course of about 6 weeks, very slowly and am now consuming upwards of 2700 calories (my TDEE) and maintaining. Of course, I'm also maintaining my activity level, especially the weight lifting part...maybe my muscles are just happy to have all of those extra calories because my linear strength gains went through the roof for those 6 weeks or so.