Question: How does eating before a run influence the fat burning?
Jeff: According to the physiology experts and dietitians consulted, fat burning is not affected by what you eat before the run. The function of a pre-run snack is to get your blood sugar level where you want it to be for the run. There are a wide range of foods used for this. Protein is not the best choice, but you should go with what works for you. Some don’t need to eat anything. Some like to have a little carbohydrate to lift the blood sugar level, within the 30 minute period before a run–especially if it is lower than normal. Most of the runners I’ve worked with on this issue have found either an energy bar (with a glass of water or cup of coffee) or a sports drink that works best for the individual. If a drink, it usually works best when taken within half an hour of the start. Accelerade has been the most popular product. Energy bars often work well when taken about 45-60 minutes before the start. Again, do what works best for you.
Question: Several of the strength training experts I’ve talked to tell me that I must exert my muscles fairly hard to burn fat. In your book Running & Fat Burning for Women, you say that running slower is better. Explain how slow exertion burns more fat.
Jeff: While you will hear a lot of opinions on how to burn fat, all of the significant research on fat metabolism I’ve seen shows that you must be exercising in the “aerobic zone” at a very easy pace, for you to burn fat. The higher the level of exertion, the less likely there will be enough oxygen available to the muscle, which is necessary for fat-burning. Even when the pace is a little bit too fast, the muscles start to shift burning glycogen as fuel (stored carbohydrate) which results in more huffing and puffing and worn-out muscles. Not only do you not burn as much fat during exercise, you can’t go as far, so you cannot burn as many total calories. Slower running, with more frequent walk breaks will shift you into to the fat-burning zone more effectively.