A study published this spring in Journal of Applied Physiology looked at whether what you eat right after exercise can impact your metabolic responses and for how long afterwards—but with a twist. We already knew that restricting carb intake after a workout slows down how quickly your muscles can replenish their glycogen stores, but this latest study compared the effects of low dietary carbohydrate versus low energy intake after exercise on insulin action the next day.
Nine healthy men completed four trials: one when they did sat around and did nothing, and three other times when they exercised moderately on a stationary cycle or treadmill until they expended ~800 calories. Following one of the exercise sessions, they ate enough calories and carbs to maintain nutrient balance. After the other two exercise sessions, though, they either had a diet that was low in carbs or low in calories. The morning after exercise, the men had their insulin sensitivity tested. Interestingly, having a low carb intake after exercise, but not eating too few calories, made people the most insulin sensitive. It turns out that withholding calories mobilizes blood fats, and those apparently decrease insulin action.
So, what does this mean for you? If you have type 2 diabetes or are normally insulin resistant and want to have the greatest insulin action the day after exercise, eat enough calories, but go low on your carb intake. If you normally take insulin and you’re trying to prevent post-exercise lows, this is definitely not the best strategy! In that case, go back and read my column on why chocolate milk is one of the best post-workout drinks there probably is.