Lately, I have been receiving a lot of e-mails and questions about how to burn off fat. I think that many people are especially interested in this now because summer is basically here and everyone wants to look their best in fewer clothes. There seems to be an infinitely vast amount of diets that address this problem, each one saying that it has the solution. In my opinion, losing fat is a mental, physical, and nutritional challenge. Here, I will be talking about the physical aspect of losing fat; how you can benefit from physical activity. I will include things like type of exercise, duration, frequency, and intensity.
First, you need to record your weight and try to get a body composition test done in order to find out your body fat percentage. It might be depressing to find out at first, but I think it is beneficial to have. This way you can monitor your progress through an exercise program. The progress that you experience acts as a reward for your activities.
What Type of Exercise?
Now, as far as what type of exercise you should do, consider this. Anything is better than nothing. You can judge what type of exercise that you like and what works for you. I feel that it is the duration, frequency, and intensity that matters the most in activities. Personally, I run or ride a stationary bike. To me, I feel that these two exercises cause me to expend the most energy. In addition, running and biking are simple, you don't have to rig yourself up to a machine, punch in a bunch of keys, or have to put up with cardio freaks looking over your shoulder to see how much more time you have on their favorite machine. Don't get me wrong, treadmills are great if running outside is too hard on your knees or ankles. Many people like to swim because they feel that it is a total body workout. If this applies to you, be aware that it is not a weight bearing exercise and therefore little resistance is used. This aspect will prevent bone strengthening (more important for women than men, statistically). I do both running and biking so that it will take me longer to adapt to either exercise. Also, if I ran all the time, my knees would really take a beating, thus impairing my leg workouts. The bottom line is that anything is better than nothing, and if you feel like you are really being challenged with your exercise of choice, stick with it, but don't be afraid to try other exercises.
What Does the Body Use for Fuel?
First off, you need to know a little bit about fuel utilization in your body. I've briefly described all three energy pathways of the body so that you will know what's going on. There are three energy pathways of the body, phosphocreatine shuttle, glycolysis, and oxidative metabolism. Phosphocreatine (PCr) yields low amounts of energy at a very high rate and is used in very high intense exercises such as sprinting. Glycolysis breaks down glucose for more energy than the PCr system, but at a little slower rate. It is used as the next energy source when the PCr system runs out. Lactic acid production is a key characteristic of this pathway. That's right, when you're lifting weights, lactic acid is the burn you feel towards the end of a set. That is how you know that you are using glycolysis as the major pathway for fuel. Finally, oxidative metabolism can use fats, glucose, or proteins for energy. This pathway is the final energy pathway; it yields the highest amount of energy, but at the slowest rate. These pathways are triggered in a cascade fashion. At the beginning of an exercise, the PCr system kicks in order to give your body energy quick since you're going from rest to active. After the PCr stores run out (in about 1-5 seconds), glycolysis kicks in for about the next 45 seconds. Finally, oxidative metabolism starts at about a minute into an activity. Now, there is some overlap with these systems. For instance, PCr and glycolysis can be going on at the same time as the transition is made between the two systems. Similarly, oxidative metabolism and glycolysis are both going at the same time up until about 10 minutes of activity.
Duration is key.
There are many conflicting views on just how long you should go for. I like short and intense exercise, usually no more than 15 minute bouts. However, according to the literature, bouts of lower intensity and longer duration burn more fat. Exercise bouts of higher intensity and shorter duration tend to burn more glucose. At the beginning of every exercise, you burn more glucose, and less fat (in the form of free fatty acids). This is because of the cascade effect previously mentioned. If you sustain the exercise for about 20 minutes, you reach a crossover point in which your body burns fat and glucose at the same percentage, 50/50. After that point, your body decreases the amount of glucose used (in order to preserve glycogen for the maintenance of blood glucose and fuel for the brain) and increases the amount of fat used for energy. This is what you want! This is when oxidative metabolism is the sole pathway for energy production. It is called oxidative because you need oxygen for the pathway to run, if you don't have oxygen, glycolysis begins again. Considering all of this information, I still think that fat loss can be achieved through high intensity exercises such as sprints. How can you say otherwise when you consider sprinters? Most real deal sprinters do not have high aerobic endurance, yet they are shredded. This is the idea that I go by: marathon runners, for the most part, are pretty thin and lack muscle mass and sprinters are thin too, but have high amounts of muscle mass, relatively speaking. If you go by the longer duration method, I would exercise for about 45-60 minutes, and if you go by the shorter duration method, I would exercise no longer than 20 minutes.
Intensity is also a major issue considered in an exercise program. The higher the intensity of the exercise, the more glycolysis, and less oxidative metabolism you do. This means that you burn less fat with higher intensity. The lower the intensity of the exercise, the more oxidative metabolism, and less glycolysis you do. This means you burn more fat with lower intensity. However, there is a cut off point, and the problem is still: what intensity is needed to burn the most fat? The lactate threshold is that point at which if you increase the intensity of your exercise one bit, you'll fatigue, but if you maintain the intensity that you're at, you can go forever, it seems. This is the intensity that you want to be at, right below your lactate threshold. At this point, oxidative metabolism is running at its maximum rate while glycolysis is lying dormant. This means once the crossover point has been reached, fat will be burned at a max rate. According to the literature, this ideal point is 50% of your maximum exercise capacity. Don't worry about that, just go by feel; the more you exercise, the more you'll know where your lactate threshold lies.
Frequency plays a major role also because undertraining and overtraining are both issues. In order to avoid both, you need to be reasonable in designing your program. I would think that exercising more than 5 days a week would be too much, but less than 3 days per week is too little. I like doing cardio twice a day (when I start doing cardio workouts) every other day. I feel like my metabolism speeds up even more after the evening session rather than running once in the morning. This is also because I do high intensity workouts; if you do long duration, low intensity, keep your work session to once per day. Also, I don't think it's a good idea to do an intense weight training session following or followed by a cardio session. To me, this is simply too much for your body; it needs a break to recover. However, the exception lies in the intensity. If both sessions are of low intensity, then it's fine to do both back to back (just make sure you stay hydrated!).
Well, that about sums up the exercise portion of the fat loss program. I hope that I have given enough information for you to form your own program that will work for you. I am also planning to include the nutritional and mental portions very soon. Good luck, and email me with any comments/questions!