Ask the RD

Answer: Postexercise fuel is all about recovery. First priority is hydrating to replace any fluid lost; next step is consuming carbohydrate combined with protein for greater glycogen storage. After endurance exercise, the recommended carb-to-protein ratio is 3–4:1 (3–4 grams of carbohydrate for every gram of protein). Depending on timing, this may be a small snack or your next meal.

Consuming protein after a workout is important. In addition to helping replenish glycogen stores, protein provides amino acids to build and repair muscle tissue. Ten to 20 grams is shown to be effective. Based on the evidence—and my professional preference—here is my rank order of the three protein types to use postworkout:

1. whey

2. soy

3. casein

All provide the essential amino acids, but whey (a milk protein) also contains branched-chain amino acids, including leucine. Whey is an optimal protein to consume immediately after a workout because it is rapidly digested for greater muscle protein synthesis.

Also a milk protein, casein is digested more slowly and is best when combined with whey (think chocolate milk). Soy is quickly digested and is a good plant-based protein rich in antioxidants called isoflavones. Try them all and choose the one that works best for you.

Good postworkout food choices include a shake made with whey protein; low-fat yogurt and banana; whole-grain cereal and low-fat milk; tuna on whole-grain bread; and low-fat cheese with apple slices.