Exercise on a fast day

This topic contains 5 replies, has 5 voices, and was last updated by franfit 10 years, 6 months ago.

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Imadamdylion

4:18 pm
16 Jun 14
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If I burn calories exercising on a fast day, does that mean I can have 500 calories PLUS whatever I have burnt off?

barbarita

4:30 pm
16 Jun 14
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No, stick to a 500 calorie maximum and regard your exercise calories as a bonus contribution to your deficit.

Stef.

4:51 pm
16 Jun 14
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Well…I do it my way and yes I eat of my exercise calories back.

Let me explain:

I work out with a heart rate monitor and a multi sports watch so I know pretty exactly how many calories I burn, regularly in excess of 1000.

I have been on the 5:2 for over six months and I am very close to maintenance (500 grams missing). My goal is not only to lose the 500 grams but overall fitness, health and muscle retention.

It is VERY difficult to built muscle and impossible (!) when you are in calorie deficit! The best you can do is trying to maintain your existing muscles by doing weight or resistance training. If I do not eat some if not all of my exercise calories back, I risk losing the existing muscle mass.

This can lead to a downward spiral: the more muscles you have the more calories you burn even during times that you do not move. So losing muscle is counter productive.

I know it says somewhere you should not eat them back and at the beginning of your 5:2 diet it might be good to not do so, but always keep in mind, you do NOT want to lose your muscle mass.

Best of luck
Stef.

simcoeluv

5:28 pm
16 Jun 14
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Hi:

The concept of ‘eating back’ is interesting. If you believe in the concept, then you could apply it seven days a week – eat more whenever you exercise.

But exercise calories are already included in your TDEE, so if you ‘eat back’ then you will be by definition ‘overeating’.

Also, people tend to not remember that if they don’t exercise, they still burn calories. So if you compute you burned, say, 400 calories while you were exercising, you did not burn an extra 400 calories. The ‘extra’ number would be somewhat less than 400.

If you ‘eat back’ on diet days, you also reduce the calorie restriction that is the secret to IF. So if you burn 1000 calories exercising on a diet day and eat them back, you will eat 1500 calories and have little calorie restriction.

Research shows that a very large majority of weight lost via IF is fat weight – much more so than with standard reduced calorie diets. I guess it depends on what your goal is. If it is to lose weight, then eat less. If it is to build muscle, then eat more and lose weight more slowly.

Whatever works for you!

Stef.

6:16 pm
16 Jun 14
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I am not aware that exercise calories are included in your TDEE if you set it to sedentary and then add the exercise calories extra.

I am fully aware that you burn calories while sleeping. The average amount of calories you burn by doing nothing is your TDEE set to sedentary divided by 24. As you already burn roughly somewhere around 70 calories per hour (in my case of a TDEE or roughly 1700) you would have to deduct this from your exercise calories or alternatively, just reduce the amount of exercise calories that you eat by around 25-30%.

I fully understand that you loose more weight if you do not eat some of your exercise calories back but in the longer term I believe this can be counter productive as muscle loss can be a side effect of losing weight too quickly.

If I burn 1000 calories and only eat 500 than I am in a minus of 500 which means not enough fuel for my body.

I would love to see some comments from Michael about this as he is not really doing exercise, apart from HIIT a couple of times per week and he only started to introduce exercise after being in maintenance!

As you rightly say, it depends on your goal and I also believe on how long you have been doing this. As argued in the other thread about ADF, I believe it is vital to eat them back when you are dieting every second day. Re the other beneficial side effect of intermittent fasting, you might be right that eating your exercise calories back might be not good for those, but then is this REALLY thoroughly researched?

Dr. Krista Varadi is even saying they do not know enough about the side effects of intermittent fasting and to the best of my knowledge there has not been enough research to conclusively say what the side effects are. It is also interesting that not everybody experiences those positive side effects, rather some experience negative side effects.

Anyhow, I will rest my case as I believe for beginners to follow the rules is quite important to get into a routine. If you up your exercise level to an extent where you need to refuel your body you might want to reconsider. I do at least two hours of sport per day and for me the refueling is an important health aspect.

Stef.

franfit

9:45 pm
16 Jun 14
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Imadamdylion, if you are just starting 5:2 because you have a lot of weight to lose and are doing a fairly ordinary amount of exercising, the usual practice is not to ‘eat back’ exercise calories burned. If you do very vigorous exercise and are already in a normal weight range, you might need to make an adjustment to that. It depends on what your goals are.