Fueling Your Post-Workout

Last Tuesday began for me like so many other week days: Up at 5 a.m. for a five-mile run with some friends, home by 6 and into the shower, then tag-teaming with my wife to nudge our kid up and out the door with a packed lunch and school bag by 7:45. By the time I sat down at my desk it was almost 8:15: I had been up for over three hours and hadn’t yet had breakfast.

That’s often the case, not just for me, but for any busy person: Distracted, over-scheduled, or just not hungry, post-workout fueling can often be an afterthought, if a thought at all. On those very busy mornings, between stomach growls and to-do lists, I sometimes have a passing moment of panic: Have I just undone all the exercise-related good I did for my body by skipping the right post-workout fuel?

As with so many things related to health and well-being, the answer is: Yes, maybe, but it depends.

What’s happening post-workout

If you’ve worked your muscles hard enough while exercising—and I’m not talking a stroll for a mid-morning coffee—you’ve done a couple of things. You’ve spurred your body to use up some energy stores in the form of fat. You’ve also depleted your sugar reserves, and torn muscle fibers, which, counter-intuitively, stimulates stronger muscles. So your post-exercise body is both recovering and growing, which means it’s searching for good-quality fuel to assist with that process. That fuel comes in the form of sugar and carbs for energy, and protein to build back the muscles that have exerted themselves.

So about that timing…

The commonly accepted wisdom is that if you’ve worked out hard—say, a vigorous run that lasts about 45 minutes—you need to eat within an hour or all your good deeds have been undone. Other studies have shown that the ideal post-exercise eating window is two hours and not immediately after exercise. But then some recent research indicates that while those guidelines are good and important, the timing may actually be a bit more fluid.

A 2013 study in the Journal of the International Society of Sports Nutrition found that high-quality protein—which builds strength—is important, but as it relates to what and when you’ve eaten before you’ve worked out. In general, the study found that “pre- and post-exercise meals should not be separated by more than approximately 3–4 hours, given a typical resistance training bout lasting 45–90 minutes.” But, the authors stressed, that timing is flexible depending on the person, the exercise type and length, and the food.

The study also found that carbs, which help build endurance, are important, but indicated there’s no definitive guideline on how much is needed. According to the American College of Sports Medicine, 30 to 60 grams of carbs (about two slices of whole wheat bread) eaten a half hour after a workout is best.

Post-exercise, it’s also easier for your body to gobble up sugar and transport it to your muscles for fuel, according to the Journal of Applied Physiology. Called insulin sensitivity, this complex process is impaired in people with Type II diabetes, making exercise even more important for everyone in order to regulate day-to-day interactions in the body.

The post-workout food fad of the moment is chocolate milk, for a number of reasons. It’s a liquid with carbs and protein as well as a little bit of sugar, vitamins, and calcium to boot. A 2012 study in Medicine and Science in Sports and Exercise found that post-exercise participants who drank chocolate milk had improved protein balance, glycogen stores, and performance. Below is a graph that illustrates the effects of drinking milk post-exercise compared to soy and carbohydrates.

So what’s the answer?

I’m in no danger of making the Olympics. But I do like to push myself with exercise and have, through the years, increased my running mileage and my cross training. And I want to stay healthy and active my whole life. So what’s the takeaway for average, every day people like me who workout regularly and want to maximize the benefits?

• Timing matters. Ideally, it may be best to give your body a light carb and protein combo right away—that 8 ounces of chocolate meal right when you finish sweating—and then a healthy meal an hour or two later. That quick post-workout fuel helps your body build its muscle glycogen stores, too.
• What you eat matters. That protein-carb combo is going to help you build strength and endurance, which means that you’ll be better primed for your next workout. But quality is important. You can’t eat whatever source of carbs and protein you can lay your hands on. Donuts? Probably not. A sports drink? Check the calories and sodium. An energy bar? Look at the fat and calories first.
• How hard you’ve worked out matters. If I do a quick 20-minute interval session, I probably don’t need to worry about whether I eat right away. But post long run, even if I’m not hungry my body is starving and I need to fuel it.