Eating back calories burned from exercise? Why?

MFP has the deficit for you to lose 2 lbs a week already built into your daily target. That is if you did no exercise at all. The site has you eat exercise calories back so you are not eating at a level that is too low for a safe weight loss.

It depends on how you set your calorie goal. If you do it through MFP, it sets the goal based on the loss you tell it you want (which for the majority of people means the max goal that MFP considers safely possible, either 2 lbs or 1 kg/week, depending) assuming that you will not exercise. Then, if you do, it adds the exercise back in and increases the calories.

You can compare this to an alternative way of setting a goal which is to cut 500 calories (for 1 lb) from food and plan to exercise another 500 calories on average (for another 1 lb). As you can see, if you do the planned exercise, that and the MFP way end up the same, it's just that MFP gives you a higher goal to start so you won't lose less if you fail to exercise. (You could do this same method through MFP directly by choosing 1 lb/week and not eating exercise back.)

The reason you eat exercise back, then, is because cutting 1000 calories plus adding exercise is extremely aggressive and for everyone but the super obese (who likely are not able to exercise extremely hard) it's going to be more aggressive than is ideal. This is especially the case for the smaller people who often choose 2 lbs/week when they'd be better off at 1 lb or less.

The argument against eating exercise back is that a lot of people don't log that well and it's easy to overcount exercise, so it could all wash out with the exercising making up for logging errors. If you are someone who tends to log more loosely and especially if your exercise isn't that intense, I think that's fine. I also think that someone who mostly does a lot of walking or other regular exercise that isn't super intense might do well just putting in a more active activity level -- as someone who does TDEE method, I get not wanting to bother logging all exercise and trying to estimate the calories burned. But I DON'T think this is a good approach if you do lots of intense exercise--for example, running 40-50 miles a week and then saying it all evens out. It won't unless you are a truly dreadful logger, so you are likely to be undereating beyond what's typically recommended and creating an overly aggressive deficit.

Philminator wrote: »

Ah ok thanks. I have in MFB 5x a week walking for 30 min. So it takes into account that. With any extra exercise I do, I guess I should eat back some of it so I don't crash. Thanks for the info

If you mean when you set it up and asked you what exercise you do, that's something that really confuses people (it did me when I started), but it does not take that into account. It just asks you that so you can set it as a goal for yourself. So you would want to include it. That said, that's the kind of exercise that I think can often be covered by making sure you have an appropriate activity level (like lightly active, depending on what else you may do) and not just sedentary.

Philminator wrote: »

Ah ok thanks. I have in MFB 5x a week walking for 30 min. So it takes into account that. With any extra exercise I do, I guess I should eat back some of it so I don't crash. Thanks for the info

NO, this is just a fitness goal, it has nothing to do with your caloric intake.

Nothing to add really to what anyone else has wrote, I have lost 50lb and I don't usually eat many exercise cals back. If I'm hungry I'll eat 100/200 or so back, if you don't you may feel like you have zero energy.

I just wanted to say well done on losing 100lb that's bloody amazing!!!

Philminator wrote: »

Oh lol. Oops, I thought it already did. Thanks for clarifying that. It's assuming I'm sitting on my *kitten*. I put that I weigh 230 pounds and want to be 200 @ 2lbs a week so it gave me 1470 calories, which isn't a lot. So I guess if I work out at gym or shovel snow an hour at a time, eating back 50-75% of calories burned won't slow my progress.

You got it. I like this me because if I sit on my hands I still lose or maintain. I use exercise for cardiovascular and strength benefits.

Philminator wrote: »

Oh lol. Oops, I thought it already did. Thanks for clarifying that. It's assuming I'm sitting on my *kitten*. I put that I weigh 230 pounds and want to be 200 @ 2lbs a week so it gave me 1470 calories, which isn't a lot. So I guess if I work out at gym or shovel snow an hour at a time, eating back 50-75% of calories burned won't slow my progress.

That's basically it. You don't want to go too low or you will lose lean body mass.

I err on the conservative side and allow some wiggle room. I have MFP set to lose 1 lb. a week and eat back about 1/3 to 1/2 of my exercise calories because I assume they are overestimated. I have averaged 1.3 lb a week loss for the 51 weeks I have been on MFP. I could try to be more exact but this is working for me. I am eating plenty (currently 1800 calories a day), have energy, and am rarely hungry.