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.

營養學雜志近期發布一項研究，結果表明鍛煉之前吃富含“釋放緩慢”碳水化合物的一餐，比如燕麥或麩麥片,可以幫你燃燒更多脂肪。研究人員檢測了8位健康女性吃完兩種早餐后的燃脂率：一天是牛奶拌穆茲利混合麥片、桃、酸奶和蘋果汁，另一天是脫脂牛奶拌玉米片、涂抹人造奶油和果醬的白面包和能量飲料。兩頓早餐含有近似的熱量值。前一種早餐屬于低血糖指數的一餐，而后一種是高血糖指數的一餐。血糖指數衡量食物提升血糖的速度。與高血糖指數食物相比，低血糖指數食物讓血糖含量波動更小。一般來說，含有蛋白質、脂肪和/或纖維——消化得更慢——屬于低血糖指數一類，大部分是碳水化合物的食物（如白面包）不在其中。當那些女性攝入低血糖指數食物時，60分鐘走路燃燒的脂肪是攝入高血糖指數食物的兩倍。原因在于，穆茲利早餐消化得更慢，與高血糖指數的玉米片相比，前者使血液中葡萄糖水平變化幅度小。反過來，胰島素水平也不會有大幅改變。因此，諾丁漢醫學院研究主任，伊恩·麥克唐納博士認為這解釋了吃穆茲利的女性為什么消耗了更多脂肪。在調節身體儲存脂肪上，胰島素起著相應作用。所以，胰島素水平越低，對燃燒脂肪越有幫助。底線是：如果你想燃燒更多脂肪，在鍛煉前選擇低血糖指數的食物，比如燕麥片，別吃像白面包之類高血糖指數的東西