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A friend of mine told me that you can pretty much eat whatever you want within about 15 minutes of a big exercise session without putting on weight. I can't really understand the science behind this. Is there any truth to this?

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within 15 mins - 1 hour there's a small window of time that you can intake carbohydrates that would be absorbed pretty quickly. However, in take too much junk is always a no no. –  kjy112 Mar 1 '11 at 21:29
    
I would choose not to eat anything you want but I would at least eat ssomething so you don't stave. –  Benny Mar 6 '11 at 5:02
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Even if this was true, your muscles still need proteins to grow and repair. Choose your post-workout meal carefully –  bobobobo Jul 2 '11 at 5:51
    
@Benny. Oh, bad, bad advice. fitness.stackexchange.com/questions/3480/… –  Ryan Miller Sep 5 '11 at 20:53

4 Answers 4

up vote 18 down vote accepted

This is not true. Your body will process the food that you ingest, and if the caloric intake of the food is greater than the amount of calories burned during the ensuing exercise, you will gain weight.

You can have some carbohydrates before your workout if you find that your diet doesn't supply you with enough energy to not feel weak or excessively tired during your workout. You can also add protein before your workout if you find yourself incredibly hungry in the middle of your exercise. Again though, if you take in more than you burn, you will gain weight.

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+1; also, calories aside, unhealthy food is always unhealthy no matter what and how you exercise. –  Alex Florescu Mar 1 '11 at 20:56
    
i think the open window after workout is between 15-60mins and intake for the food has to be good quality food...something like chocolate milk –  kjy112 Mar 1 '11 at 21:37
    
@kjy112 erm, chocolate milk with the sugar (or corn syrup, ugh!) that gets dumped in just about any grocery brand? I think I'd stick to regular milk (whole milk too, but I suspect mentioning that could open up a holy war!) –  Greg Mar 1 '11 at 22:26
    
@Greg - the point is the carbohydrates (sugar) in this scenario (if it were true). The carbohydrates will give you a bigger energy boost faster than fat or protein will. –  Nathan Wheeler Mar 1 '11 at 22:30
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@Greg - an ounce of prevention is worth a pound of cure. –  Nathan Wheeler Mar 1 '11 at 22:43

I understand that there is a window (not sure if it's 15 minutes exactly, I suspect longer, and there's probably a gradual drop-off) after a heavy strength-training session in which your body is in a hormonal state that causes it to route most e.g. carbohydrates into repair and refueling your muscles & supporting systems, rather than routing it into fat storage.

Keep in mind as well, however, that digestion takes time and certainly more than 15 minutes so you might be better off doing that eating before or during your workout (not to the point of being stuffed) or immediately afterward.

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Why the downvote without explanation? –  Greg Mar 1 '11 at 21:54
    
@Greg - sorry, I apparently didn't submit it. The hormonal state will still not account for excess calories. At best you will stall any attempts at weight loss, and at worst you will gain weight. Your body absolutely will put energy to repairs first, but it will still convert excess to fat. –  Nathan Wheeler Mar 1 '11 at 22:20
    
@md5 - no problem with comment delay - just trying to learn here! :-) I think you're right about excess calories, but the question becomes the caloric intake that qualifies as excess. During that state immediately after a heavy workout, "excess" will be much higher than normal. –  Greg Mar 1 '11 at 22:24
    
@Greg - Excess will consist of everything you ate that you didn't burn. –  Nathan Wheeler Mar 1 '11 at 22:27
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@md5 Everything you ate you didn't burn DURING REPAIR, which should be quite a bit more than otherwise. Steroids aside, all the big gym rats get big by eating first and foremost! They don't get fat even though they take in a ton of calories, and it can't all be explained by calories burned during their actual workouts. –  Greg Mar 1 '11 at 22:35

The information is sort of correct, except it's supposed to be roughly a 2 hour window of increased metabolic rate after doing exercise that is primarily anaerobic. However, this doesn't mean you can eat anything you want, in fact almost the opposite - the benefit comes from eating a small snack during this period and enjoying the 'free' increased calorie burn.

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There was a recent study suggesting that just the opposite is true. Generally exercise causes short term appetite increases. This study's results showed that if you ate something before exercise, your brain doesn't compensate for those calories as much as it should, so you end up eating more overall.

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