Let's begin with what the current research on exercise physiology tells us. It is well-established that it takes approximately 30 minutes of any kind of exercise for the body to burn off its glycogen (stored sugar) reserves and begin burning fat. So, most experts recommend at least 30 minutes of exercise, and generally 60 minutes or more may be recommended to get a good amount of fat burning. Now, if you are going to be exercising for 30 to 60 minutes, or maybe more, what type of exercise would you be able to do for that length of time? It probably would have to be low to medium intensity. In other words, you're probably not going to be able to run full speed or do any other type of high-intensity exercise for 30 to 60 minutes without a rest, unless you happen to be an elite athlete, and even then you'd be struggling. So, by default, the common recommendation for exercise to lose weight has been 30 to 60 minutes of low to medium intensity aerobic exercise. Aerobic translates to "in the presence of oxygen", which in common language means that aerobic exercise is any type of activity that you can do without gasping for breath.
In recent years, some experts have changed their recommendations to using a more intense anaerobic ("without oxygen") exercise program for weight loss. This would include things like intense weight lifting, and something called "interval training". Interval training involves brief bursts of high intensity activity with periods of rest or low intensity activity in between. For instance, your could sprint at full speed for 30 to 60 seconds and once you were winded, you could walk at an easy pace for a couple of minutes until you could catch your breath, then repeat the cycle several more times.. Because this kind of workout is much more strenuous, it is performed over a much shorter period of total exercise time - about 20 to 40 minutes (at least half of which is rest time), as compared to half an hour to an hour of non-stop exercise as is recommended with low to medium intensity aerobic workouts. The question is, how do the two types of exercise compare in terms of their ability to promote fat burning?
The aerobic exercise promoters point to the research that was mentioned earlier that has shown that any exercise, no matter how intense requires at least 30 minutes to use up the body's stored glycogen (the body will normally burn glycogen before it will burn fat) before fat burning can begin. So, they say, short periods of even highly intense exercise won't burn much fat and is therefore not a good choice for promoting weight loss. But they are only seeing part of the story.
It is true that you must exercise for at least 30 minutes to begin to achieve fat burning - but that's at the time you are exercising. Brief bursts of intense anaerobic exercise does something that even quite a lot of low to medium intensity aerobic exercise does not. Intense anaerobic exercise stimulates the production of growth hormone, which is a strong stimulator of fat burning. The thing is, the release of growth hormone triggered by intense anaerobic exercise comes 24 to 48 hours AFTER the exercise, and then it produces considerably more fat burning than is possible with all but extremely long periods of low to medium intensity aerobic exercise.
Because of this effect, most people will lose weight much more easily by doing shorter periods of more intense exercise. 20 to 40 minutes of heavy weightlifting, interval training (which could be done on foot, on a bicycle, swimming, kickboxing, etc.Any kind of activity in which there are periodic bursts of intense exertion interspersed with rest periods, or periods of low intensity activity is typically preferable in the long run for weight control than even long hours of lower intensity aerobic exercise.
Now, you'll notice that I said "most people". There is an exception to the rule. People under considerable stress, either emotional or physical, or both, in their daily lives are prone to overworked adrenal glands. The adrenal glands do a lot of things in the body, but with regards to weight loss, they produce two hormones. Cortisol is one of the hormones, and it stimulates fat storage in the lower abdominal area. This is typically a saggy, pendulous fat held below the waistline. The other hormone the adrenals produce is adrenaline (also called epinephrine), which actually promotes fat burning. Since the adrenals produce cortisol which causes fat deposition and adrenaline which promotes fat burning, you might assume that these two hormones cancel each other out. The thing is, cortisol can be produced by the adrenals for a much longer time than adrenaline, which is produced for brief periods, so in the long run, the cortisol effects (fat storage in the lower abdomen) win out when you are under chronic stress.
The adrenals are influenced by physical stress as well as mental stress, so for someone who is under a lot of stress in general in his or her life, high-intensity exercise will only add to the total stress and will tend to make the adrenals produce a lot of cortisol, and therefore will tend to promote lower abdomen weight gain. Yes, you read that right - excessive exercise for someone under a lot of stress can actually cause that person to deposit MORE fat around the lower belly! This can result in the frustrating situation in which one exercises more and more and harder and harder to try to get rid of that lower abdomen stomach "pooch", but never can seem to get rid of it. Because the intense exercise is stimulating more cortisol production, that person is fighting a losing battle. Because of this effect, it is recommended that people under a lot of stress and/or who have most of their weight held in the lower abdomen stick to relatively low intensity aerobic exercise. This kind of activity is usually helpful for controlling stress and reducing the level of cortisol, thereby making it easier to get rid of the deposition of fat around the lower abdomen.
Hopefully you now have a better understanding of how to use exercise to maximum benefit for weight loss.
