Eating a meal made with "slow-release" carbohydrates, such as oatmeal or bran cereal, before you exercise may help you burn more fat, suggests a recent study in the Journal of Nutrition. Researchers assessed the rate of fat burn among eight healthy women after they ate two breakfasts: muesli with milk, peaches, yogurt and apple juice on one day; cornflakes with skim milk, white bread with margarine and jam and an energy drink on another day. Both meals contained similar amounts of calories. The first breakfast (muesli) was a low-glycemic-index (GI) meal, the second was a high-GI meal. The glycemic index ranks foods based on how much they raise blood sugar. Lower-GI foods produce smaller spikes than higher-GI foods. Generally, foods that contain protein, fat and/or fiber—and are digested more slowly—fall lower on the GI scale than those that consist mostly of carbohydrate (e.g., white bread). On the days when the women ate the low-GI breakfast, they burned nearly twice as much fat during a 60-minute walk as they did on the days when they ate the high-GI meal. Here’s why: Because the muesli (low-GI) breakfast was more slowly digested, it didn’t spike blood-glucose levels as high as the cornflake (high-GI) breakfast did. In turn, insulin levels didn’t spike as high either—which probably explains why the muesli-eating women burned more fat, says Ian MacDonald, Ph.D., director of research at the University of Nottingham Medical School. Insulin plays a role in signaling your body to store fat. So, lower levels of insulin might help you to burn fat. Bottom line: If you’re looking to burn more fat, pick low-GI foods, such as oatmeal, over high-GI foods, such as white toast, before your workout.

营养学杂志近期发布一项研究，结果表明锻炼之前吃富含“释放缓慢”碳水化合物的一餐，比如燕麦或麸麦片,可以帮你燃烧更多脂肪。研究人员检测了8位健康女性吃完两种早餐后的燃脂率：一天是牛奶拌穆兹利混合麦片、桃、酸奶和苹果汁，另一天是脱脂牛奶拌玉米片、涂抹人造奶油和果酱的白面包和能量饮料。两顿早餐含有近似的热量值。前一种早餐属于低血糖指数的一餐，而后一种是高血糖指数的一餐。血糖指数衡量食物提升血糖的速度。与高血糖指数食物相比，低血糖指数食物让血糖含量波动更小。一般来说，含有蛋白质、脂肪和/或纤维——消化得更慢——属于低血糖指数一类，大部分是碳水化合物的食物（如白面包）不在其中。当那些女性摄入低血糖指数食物时，60分钟走路燃烧的脂肪是摄入高血糖指数食物的两倍。原因在于，穆兹利早餐消化得更慢，与高血糖指数的玉米片相比，前者使血液中葡萄糖水平变化幅度小。反过来，胰岛素水平也不会有大幅改变。因此，诺丁汉医学院研究主任，伊恩·麦克唐纳博士认为这解释了吃穆兹利的女性为什么消耗了更多脂肪。在调节身体储存脂肪上，胰岛素起着相应作用。所以，胰岛素水平越低，对燃烧脂肪越有帮助。底线是：如果你想燃烧更多脂肪，在锻炼前选择低血糖指数的食物，比如燕麦片，别吃像白面包之类高血糖指数的东西