Eating back the exercise.

mrFerris · January 2012

I am wondering if anyone can give me the scientific reason for eating the extra calories we are exercising? I understand the point of exercising to burn calories and get fitter but I am wondering why we need to eat the extra calories we burnt off! I know if I understand the reason for it I will feel less guilty about adding that extra 100 kcal after burning 100 in the walk.

Thanks.

ElizabethRoad · January 2012

Losing weight comes from your calorie deficit. If your normal daily energy expenditure is 2000 calories, and you eat 1500 calories, you have a 500-calorie deficit. That will result in a pound per week loss. If you exercise and burn another 500 calories, if you didn't eat them you'd be at a 1000-calorie deficit.

It's really simple: you need fuel to move. If you move more, you need more fuel.

mrFerris · January 2012

Losing weight comes from your calorie deficit. If your normal daily energy expenditure is 2000 calories, and you eat 1500 calories, you have a 500-calorie deficit. That will result in a pound per week loss. If you exercise and burn another 500 calories, if you didn't eat them you'd be at a 1000-calorie deficit.

It's really simple: you need fuel to move. If you move more, you need more fuel.

Hi thanks ...so all it is doing then is providing more fuel for the extra activity? I thought there was a more scientific reason behind it. That I already knew but every other diet plan I have been on didn't add exercise calories back into the food.

alyssamiller77 · January 2012

Losing weight comes from your calorie deficit. If your normal daily energy expenditure is 2000 calories, and you eat 1500 calories, you have a 500-calorie deficit. That will result in a pound per week loss. If you exercise and burn another 500 calories, if you didn't eat them you'd be at a 1000-calorie deficit.

It's really simple: you need fuel to move. If you move more, you need more fuel.

Hi thanks ...so all it is doing then is providing more fuel for the extra activity? I thought there was a more scientific reason behind it. That I already knew but every other diet plan I have been on didn't add exercise calories back into the food.

We answer this question quite a lot on this board, but I'll give it another go. MFP bases your calories goals off of a few averages. First, it calculates what it believes is your daily calories expenditure (before any workout exercises) based off your age, weight and the activity level you specified when you signed up. It uses some averages to make this calculation but in most cases it's pretty close. Next, you told MFP how much weight you wanted to lose per week. MFP knows that it takes a calorie deficit of 3500 cal over a week to lose one pond (this is a reliable constant). So it then divides that by 7 (500 cal) and subtracts that from your total daily expenditure that it calculated to set your daily goal. Simple math. Now if you go and exercise over and above your specified activity level, you burn additional calories not included in the calculation, so you now have a bigger deficit. To keep you on your goal of losing 1 lb per week, it adds those calories into you daily goal. If it did not eat those calories, you would in theory lose weight at a faster rate which depending on your circumstances could be unhealthy.

So it's just simple mathematics coupled with simple simple biological truths.

Jo2926 · January 2012

When you set up MFP you tell the computer your goal weight loss, and from this the computer sets your calories to help you lose exactly that - no more, no less. If you exercise you will burn more calories and therefore the commuter compensates, increasing the calories you should eat to still meet that same weight loss goal.

You do not have to eat these back, you could for example set your weight loss goal to 1/2lb a week, and any additional calories you burn are a bonus and you may lose 1lb. If your goal is already higher though, and you add in a significant amount of exercise, the increased deficit you create could lead to a weight loss stall because you do not fuel your body enough for the amount of exercise you are trying to do.

I think everyone is slightly different so you need to experiment to see what gets you the best results. And you need to make sure you are not overestimating the calories you burn too. I use a HRM most of the time, which shows I burn significantly less than MFP estimates.

MaximalLife · January 2012

I am wondering if anyone can give me the scientific reason for eating the extra calories we are exercising? I understand the point of exercising to burn calories and get fitter but I am wondering why we need to eat the extra calories we burnt off! I know if I understand the reason for it I will feel less guilty about adding that extra 100 kcal after burning 100 in the walk.

Thanks.

Simply stated MFP has already figured out your total calories you need to eat per day to lose 1lb etc. a week. That's WITHOUT exercise. You'll notice that when you actually add exercise in, the calorie limit goes up. Why? Because it's telling you to eat your exercise calories. Large deficits aren't really good to do because while you will lose weight, what kind of weight will it be? In many cases you'll lose lean muscle tissue which LOWERS your metabolic rate even more. Then you have to eat even less to compensate for less of a calorie burn to continue to lose the same amount of weight each week.
Be efficient. Exercise hard and eat back the calories. The hard exercise will RAISE your metabolic rate and burn more fat at rest.

taso42 · January 2012

http://www.bodyrecomposition.com/fat-loss/why-big-caloric-deficits-and-lots-of-activity-can-hurt-fat-loss.html

http://www.myfitnesspal.com/topics/show/390145-should-i-eat-my-exercise-calories

valeriek1970 · January 2012

It depends. It all depends on your daily calorie intake. Example: My calories for a day are 1210, which is pretty low. If i go much lower the body goes into starvation mode and it stores intead of burns. So if I restrict calories to 1210 then exercise and burn off say 200, then I am at 1010, which isn't enough fuel for your body to function properly. So at the end of the day after i reduced my calorie intake and have burned off calories exercising I should be at 1210. Hope this makes sense.

jacksonpt · January 2012

Eating back exercise calories is not an absolute, hard and fast rule for everyone all the time... it's just the prevailing recommendation here because it is how MFP is setup.

There are 2 ways to lose weight:

1) Set your daily caloric intake at a deficit
This is what most people do, and is how MFP is designed to work. You figure out your daily caloric need (BMR), then set your calorie goal lower than that. For example.. if your BMR is 1800, you might set your daily calorie goal to 1400. That puts you in a caloric deficit and you will start to lose weight**. When you exercise you burn additional calories. These burned calories are not accounted for in your BMR or the calorie goal you set based on your BMR. So exercising increases that caloric deficit. The thing to watch here is how big that deficit gets. Every body responds differently, but the larger the deficit the worse it is for your body (the assumption is that the larger the deficit gets the harder it is to properly fuel your body). And this is why people recommend eating back exercise calories.

2) Use exercise to create the deficit
With this method you set your daily caloric intake to equal your BRM. Then you exercise and burn calories. Those burned calories are not accounted for when you set your daily goal equal to your BMR, and thus you end up in a deficit. The size of that deficit is dependent on your workouts. You burn 75cals walking the dog and your deficit is 75 cals. You burn 500 cals running and the deficit is 500.

**This is VERY simiplified and makes A LOT of assumptions, but is good enough for this conversation.

XXXMinnieXXX · January 2012

Here's a curve ball. Lol. I'm under weight management and see 3 different dietitians all of the same opinion. I'm currently 240lbs\17 stone. They tell me I DON'T need to eat my exercise calories until I'm very close to my goal weight. [Within a healthy bmi] If you are above healthy bmi eg overweight\obese you MUST eat atleast 1200 cals as we know, but when you exercise, if your body needs more it will use your fat stores. Your body doesn't go into starvation mode through exercising the same way as undereating it does. Once your near goal you MUST eat all exercise calories back as if your body doesn't have enough food it will start to eat away at your muscles, including around vital organs and the heart is obviously a muscle. Its a myth that if your above a healthy bmi you need to eat exercise calories back. If I burn 3-400 calories I'm not usually any hungrier and stick to my 1300 calories for a 2lb loss. If I've burnt of 1000 which I do regularly I usually eat 1500ish. You only need to eat extra if your hungry and if your in the healthy bmi range. I got 3 opinions to clarify this, and its got me 59lbs down the road so far. The pic on this post is before I lost any weight... I'm now a different person and my health is so much better following the dietitians advice. If I ever felt hungry or weak etc I'd eat more, but I've been told that's the only time I need to. Hope this helps! X

jacksonpt · January 2012

Losing weight comes from your calorie deficit. If your normal daily energy expenditure is 2000 calories, and you eat 1500 calories, you have a 500-calorie deficit. That will result in a pound per week loss. If you exercise and burn another 500 calories, if you didn't eat them you'd be at a 1000-calorie deficit.

It's really simple: you need fuel to move. If you move more, you need more fuel.

Hi thanks ...so all it is doing then is providing more fuel for the extra activity? I thought there was a more scientific reason behind it. That I already knew but every other diet plan I have been on didn't add exercise calories back into the food.

It's dependent on how you calculate your daily caloric intake goal. If the program you are on accounts for exercise (as many do), then you won't want to eat them back. If it doesn't (as is the case for MFP), then you will want to eat them back.

iamMaLisa · January 2012

Losing weight comes from your calorie deficit. If your normal daily energy expenditure is 2000 calories, and you eat 1500 calories, you have a 500-calorie deficit. That will result in a pound per week loss. If you exercise and burn another 500 calories, if you didn't eat them you'd be at a 1000-calorie deficit.

It's really simple: you need fuel to move. If you move more, you need more fuel.

Hi thanks ...so all it is doing then is providing more fuel for the extra activity? I thought there was a more scientific reason behind it. That I already knew but every other diet plan I have been on didn't add exercise calories back into the food.

We answer this question quite a lot on this board, but I'll give it another go. MFP bases your calories goals off of a few averages. First, it calculates what it believes is your daily calories expenditure (before any workout exercises) based off your age, weight and the activity level you specified when you signed up. It uses some averages to make this calculation but in most cases it's pretty close. Next, you told MFP how much weight you wanted to lose per week. MFP knows that it takes a calorie deficit of 3500 cal over a week to lose one pond (this is a reliable constant). So it then divides that by 7 (500 cal) and subtracts that from your total daily expenditure that it calculated to set your daily goal. Simple math. Now if you go and exercise over and above your specified activity level, you burn additional calories not included in the calculation, so you now have a bigger deficit. To keep you on your goal of losing 1 lb per week, it adds those calories into you daily goal. If it did not eat those calories, you would in theory lose weight at a faster rate which depending on your circumstances could be unhealthy.

So it's just simple mathematics coupled with simple simple biological truths.

great explaination ! perfect

LorinaLynn · January 2012

Hi thanks ...so all it is doing then is providing more fuel for the extra activity? I thought there was a more scientific reason behind it. That I already knew but every other diet plan I have been on didn't add exercise calories back into the food.

That's because most plans factor in the amount of exercise you say you're going to do into your calorie goal.

MFP doesn't factor it into your calorie goal unless and until you do it.

It's really the same math, just with the numbers added at different times.

jetscreaminagain · January 2012

Look at the links that GuruMeditationError posted. They are what I was going to answer, and they are very enlightening. If you don't get enough "fuel for your exercise" you'll start burning the lean mass you have. That's the opposite of what you want, I bet, so it isn't a small deal.

mrFerris · January 2012

Thanks everyone ... Really appreciate that.

jillica · January 2012

Yes, great comments! I try to exercise everyday. I find that if I don't eat back some of my exercise calories, my energy starts to fade in those workouts and have almost felt sick after some of them.

Eating back the exercise.

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