A very simple plan

Muscle & Fitness, Sept, 2007 by Jim Stoppani

Q: Can I consume simple carbs (i.e., Gatorade) before I train, or will I end up crashing during my workout? If I can, what types are best?

A: Typically, we recommend about 40 grams of slow-burning carbs such as fruit, oatmeal or whole-grain bread before workouts. The reason: They provide a long-lasting form of energy that stays with you through your entire workout so you don't crash. Research not only shows this to be true but also confirms that eating slow-digesting carbs helps you burn more fat during your workout.

You can get away with having fast-digesting carbs such as white bread or Gatorade if your workout is very short (around 30 minutes) and you're fairly lean (or not worried about burning fat).Otherwise, fast carbs will spike your insulin level during the workout, causing blood-sugar levels to drop and leaving you with insufficient energy to finish the workout with the intensity needed to encourage muscle growth. The higher insulin level will also halt fat-burning that's critical during cardio workouts and when lifting weights, since you burn fat resting between sets and when the work-out is over.

Your best bet is to forgo fast carbs until you finish a session. Then you can go with 60-100 grams of fast carbs to spike insulin at a time when you want it high--after workouts, when it drives muscle growth and doesn't compromise fat loss.

Jim Stoppani, PhD, Senior Science Editor