Will Eating Chocolate Before Exercise Fatigue Your Muscles?

Sugary foods like chocolate aren't your best choice for a snack before a workout. The sugar in the chocolate may give you a little boost, but it might be followed by a dramatic drop in energy. Plus, the excess sugar can really wreak havoc on your digestive system.

While the sugar content in chocolate may vary depending on type and manufacturer, most chocolate bars are a concentrated source of sugar. When you consume sugar before you workout, blood sugar levels surge, causing a slight increase in energy levels. The increase in blood sugar, however, also causes your body to release insulin to help bring blood sugar levels back down to normal. This can cause a dramatic drop in blood sugar and energy levels, so you'll feel more fatigued during your workout.

Your digestive tract needs fluid to dilute sugary treats, like chocolate, and your muscles also need water to absorb sugar from your bloodstream. These factors can affect your hydration status. Even a slight dehydration can lead to muscle fatigue and impair performance. You should avoid sugary treats before exercise because the resulting changes in your fluid levels can cause abdominal pain and diarrhea.

For endurance athletes, caffeine can help improve performance and energy levels, according to the American College of Sports Medicine. If you're eating chocolate for the caffeine boost, though, you may be very disappointed in the results. While chocolate is a source of caffeine, most chocolate bars do not contain significant amounts -- about 45 milligrams of caffeine per bar. The college says you need about the amount found in a cup of coffee, about 100 milligrams, to feel the effects.

A 2012 study published in the European Journal of Nutrition investigated the effects of dark chocolate consumption before exercise on antioxidant status and oxidative stress in a group of cyclists. The researchers found that the chocolate improved antioxidant status and stress response, but it also caused an increase in insulin and blood sugar levels. While dark chocolate may offer protection against cell damage, it may not do much to improve energy or prevent muscle fatigue.