Slow-digesting carbohydrates are great preworkout nutrition choices because they’ve been shown in athletes to enhance muscle endurance and even increase the amount of fat burned during exercise and at rest. If you’re a regular MUSCLE & FITNESS reader, you likely already know this. The bad news is, slow carbs can be difficult to carry with you (so you have them when you need them) because they’re found in whole-food sources such as whole-wheat products, oatmeal and most fruits. The good news is, a slow carbohydrate called trehalose is found in several convenient forms, such as Accelerade powder and sports drinks.

You might not be familiar with the name, but you’ve likely had trehalose before. If you’ve eaten lobster, shrimp, mushrooms, honey or any products made from baker’s yeast, you’ve had trehalose. What’s unusual about this multifunctional carb is that it’s a simple sugar that digests very slowly because the enzyme necessary to break its bond – trehalase – works slowly. So even though trehalose is composed of only two glucose molecules, it takes longer to digest than most sugars. (Maltose, for example, behaves more like a traditional simple sugar and digests very rapidly. The enzyme that breaks down maltose is fast-acting, which is why its glucose molecules are more readily available to the body.)

When UK researchers tested trehalose on trained cyclists, subjects were given either trehalose or glucose 45 minutes before a cycling workout to see how it would affect their blood glucose and insulin levels. The scientists discovered that the glucose group had significantly higher blood glucose levels and insulin levels 145% higher than subjects who took trehalose. Too much insulin during exercise is bad news for bodybuilders because it blunts fat-burning and contributes to hypoglycemia following exercise. In fact, several subjects who took glucose before the workout experienced fatigue and lethargy, symptoms of hypoglycemia.

Some supplements, as well as the sports drink Accelerade, offer trehalose in combination with other carbohydrates. Taking trehalose along with protein within 30 minutes of starting your workout will supply your muscles with a steady stream of energy as you train and allow fat-burning to continue by minimizing insulin levels. Add trehalose supplements to your preworkout regimen, but start with small doses to assess your tolerance and give your body time to regulate the enzyme activity of trehalase. Because trehalose digests so slowly, taking too much of it at one time can cause severe stomach upset. We recommend starting with no more than 20 grams of trehalose as part of your 20-40 grams of preworkout carbs.