Ask the Doc

More exercise, more protein?

ask the doc more exercise more protein

Q  It’s summertime and I’m a lot more active—biking, swimming, playing sports—than I am in winter. What is good vegetarian fuel for when I’m being really active? What do I need and where can I get it?

 If you’re aiming to power up your athletic activities, you’ll find an endless array of nutritional products—and a cacophony of conflicting advice on what to eat and when. But a look inside those exercising muscles of yours will tell you a lot about what you really need.

When you start to exercise, your muscles get their fuel from glycogen. This long, branching molecule quickly disintegrates during exercise to free up glucose—simple sugar—which is what your muscles use for quick energy.

Glycogen is the stuff marathon runners try to load into their muscles and livers before a race. Glycogen is made from carbohydrates, and the more carbs in your diet, the more your body builds up its glycogen stores. The most healthful carb-rich foods are also the cheapest: Whole grains (such as brown rice), beans and starchy vegetables (such as sweet potatoes) provide the best carbohydrates.

Avoid carbs that are mainly simple sugars, such as sodas and candy, and refined grains (think white bread and white rice). Don’t forget water. You lose a lot of it in hot weather so be sure to stay hydrated. During a prolonged workout, drink about two cups of water (16 oz.) two hours before you start and another one-half to one cup every 20 minutes.

Q  What about protein? People are always so worried about it, but how much do I really need?

A  Well, if carbohydrate-rich foods are the fuel that powers your furnace, protein is the steel that makes up the furnace itself. That is to say, protein is not generally used for fuel but for constructing and repairing muscles and tissues.

There’s an ongoing debate about how much protein is optimal for strength training, but a small Tufts University study, published in the American Journal of Physiology in 1995, helped sort things out. The researchers put 12 middle- age-and-older men and women on a strength-training program. Everyone followed a vegetarian diet but half the participants got the usual recommended daily protein intake (0.36 grams per pound of body weight)—while the others got double that.

After 12 weeks, it was clear that there was no advantage to the higher protein diet. The extra protein was simply wasted; even with exercise, the participants needed no more than the standard amount. Although this was a small study, the findings suggest that protein needs are set by your body size and the amount of exercise you do.

Once you give your body the protein it requires, there appears to be no value in extra protein. It’s important to note that there is no requirement at all for animal protein in the diet. There is plenty of protein in beans, grains and vegetables, as well as the concentrated protein in seitan (“wheat meat”) and soy products, such as soymilk, tofu, tempeh and various meat substitutes, all of which are found in any natural food store or in the health-food section of grocery stores.

Decades ago, nutritionists thought that only meat provided “complete” protein—meaning all essential amino acids—while plant foods had to be carefully combined to provide all the necessary amino acids. The fact is, a varied plant-based diet provides complete protein without any special combining.

One last point: When embarking on a new exercise regimen, you might imagine that your nutritional needs soar. But it actually takes very little food to fuel your exercise program. For instance, next time you’re at the gym, run flat-out for a mile on a treadmill. Then push the button that tells you how many calories you’ve burned. It’s only about 100, which is less than the calories in 30 M&Ms, half a 20-oz. soda or half a small order of McDonald’s fries.

So don’t stuff yourself with protein bars and athletic drinks, thinking that you need extra nutrients. If you do, you’re likely to gain weight—a counter- productive thing to do in a gym.

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