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I hear sometimes that after running you should wait with eating for 30 or 40 minutes (may be the metabolism is still in fat burning mode?).

What is the reason for this advice? How long exactly should I wait? And is it valid for any food or is e.g. okay to eat a banana after the exercise?

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3 Answers 3

Yes, the body is still in full gear burning calories for a time (up to an hour) after exercise (especially cardio). After that your metabolism will slow again. So the idea is to burn as much fat from your body for fuel as possible, rather than fueling it with food, especially carbohydrate-rich foods which are converted faster to energy and will prevent the body from burning it's own fat stores first. However, if you aren't worried about burning fat, there's really no other reason to wait.

On the other hand, on days you do strength training or muscle building workouts, eating a short time after your workout is fine, as your metabolism isn't in high gear the same way, and the extra protein that you might consume will help to begin rebuilding your muscles.

This is not to say that you should overeat. If you take in more calories than you burn during your exercise, you will gain weight.

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I have to disagree with this one. Digestion takes several hours for complete meals. Even simple carbs (chowing down on a bagel, say) are not going to become blood sugar until much of that hour is up. Blood sugar is the only chemical pathway for stored fat in the body... –  Greg Mar 8 '11 at 16:15
    
Actually the OP asks broadly for all foods, but if you clarify your answer to represent just simple carbs (assuming you agree with me) then I won't be so opposed to it. Throwing down some candy or a sugary energy drink on an empty stomach just afterward actually might hit the bloodstream fast enough... –  Greg Mar 8 '11 at 16:19
    
@Greg Is is just the time the sugar from the eaten stuff arrives in the blood or are there also other factors (maybe the arrival of food in the stomach triggers a hormonal reaction and changes the metabolism mode)? –  pesche Mar 8 '11 at 19:46
    
@pesche Well other factors certainly could come into play (I don't think so, but I can't prove that). My objection to this answer was the idea of the new food providing fuel for the exercise. That can't happen because the body simply can't digest the food quickly enough to fit the time window that you asked about in your question. –  Greg Mar 8 '11 at 19:51
    
@Greg - I would agree that it is dependent on the food, but digestion begins immediately, and much sugar can be absorbed into the bloodstream in a matter of a few minutes after eating or drinking (a significant portion of a piece of candy can be absorbed in a matter of about 5 minutes). If you want to maximize lean muscle, avoiding non-fiber carbohydrates while the body is still in high gear is essential. –  Nathan Wheeler Mar 8 '11 at 22:19

It depends on your goals. If you want to lose weight, don't consume food after a run; wait up to two hours if you can. If you want to to go hard your next run, consume food (80% carb / 20% protein) within 30 minutes.

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Is there any reference/study that backs up your answer? I'm really looking for a long term plan for my meals post my running sessions, and I really want o make sure I've read up all the pro's and cons! –  TCSGrad Dec 4 '12 at 23:49

You get free increased calorie burning after exercise for up to two hours, so if you can hold off that long you'll still be burning calories at a higher rate than you BMR. You can drink water during this period to help stave it off, 30 minutes is about the length I can manage without grabbing at least a fruit drink.

Carbohydrates are best for post run, combined with protein on a 60/40 ratio. For example a yoghurt and sandwich - it promotes protein synthesis in the muscles and also glycogen recovery.

The first few chapters of this Anita Bean book goes into masses of detail on pre-workout, during-workout and post-workout foods.

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@Chris If I read you correctly, you speak about what and when to eat before a run, not after. I know that it's crucial to refill carbohydrates before and during longer runs. And thanks for the link, the book looks interesting. –  pesche Mar 8 '11 at 19:56
    
@pesche good point, I skim read my mistake. I've updated –  Chris S Mar 8 '11 at 21:35
    
If you're on a ketogenic diet, you don't need the carbohydrates at all. You can refuel using fat and protein only. I know several athletes who haven't really eaten carbohydrates in years (they do eat very small portions of green, leafy vegetables). No bread, no fruit, no potatoes or corn. –  Nathan Wheeler Mar 9 '11 at 15:05
    
@md5sum but surely not for endurance sports? –  Chris S Mar 9 '11 at 15:32
    
@Chris S - Yes, I run and I'm on an almost fully ketogenic diet. Most days about an hour after my run I have some 73/27 hamburger meat with a little cheese. –  Nathan Wheeler Mar 9 '11 at 15:42

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