I have determined that when I swim, based on my heart rate, I am burning an enormous amount of calories. The other day, I wore my HR monitor and based on my average HR, time spent swimming, and my weight, I burned 1053 calories. Now, the next day, I ran for 40 minutes and burned 453 calories.
I have noticed that when I just swim over a number of weeks, my LDL cholesterol readings go up and my body fat goes up as well. When I just run and don't burn as many calories (according to my HR monitor) my LDL drops, my HDLs go up, and my body fat decreases. I've noticed this now over the course of 13 years.
Anybody know of any studies out there that might explain this? Why would an activity such as swimming that obviously burns a bunch of calories cause an increase in body fat?
Here is something I found by Dr. George Best:
The adrenal glands produce another hormone that can promote weight gain though. This hormone is called cortisol, and it tends to cause the storage of fat in the lower abdomen. Unlike adrenaline which is produced for only short periods of time, the adrenal glands can produce cortisol long-term. This means that any fat-burning effects from adrenaline will be overcome in the long-run by the fat-storing effects of cortisol. From a survival standpoint, cortisol serves the purpose of providing emergency storage of fat for energy when the body is under stress for a long period of time. For human cultures in which the primary source of stress is physical stress, this fat storage can help keep people alive during extended periods of living under harsh conditions. The problem is, mental/emotional stress will elevate cortisol levels too, and for individuals who lead particularly stressful lives, the continued high cortisol levels will likely stimulate lower belly fat deposition.
So what does this have to do with exercise? Well, for someone who is under chronic emotional stress and whose adrenal glands are constantly overworked, their cortisol production is already high and their ability to produce adrenaline has been largely exhausted. If you add a lot of strenuous exercise into the mix, the result is more cortisol production. As the cortisol levels increase, there is a greater and greater tendency to store fat in the lower abdomen.
Also interesting - a scientific study of high cortisol levels in women and the storage of fat: www.ohsu.edu/.../menopausal060605.cfm
Interesting hypothesis.One confounding factor is that"moderate"exercise decreases perceived stress and so would lead to decreased cortisol levels.Very strenuous exercise does increase cortisol levels though.
Here is something I found by Dr. George Best:
The adrenal glands produce another hormone that can promote weight gain though. This hormone is called cortisol, and it tends to cause the storage of fat in the lower abdomen. Unlike adrenaline which is produced for only short periods of time, the adrenal glands can produce cortisol long-term. This means that any fat-burning effects from adrenaline will be overcome in the long-run by the fat-storing effects of cortisol. From a survival standpoint, cortisol serves the purpose of providing emergency storage of fat for energy when the body is under stress for a long period of time. For human cultures in which the primary source of stress is physical stress, this fat storage can help keep people alive during extended periods of living under harsh conditions. The problem is, mental/emotional stress will elevate cortisol levels too, and for individuals who lead particularly stressful lives, the continued high cortisol levels will likely stimulate lower belly fat deposition.
So what does this have to do with exercise? Well, for someone who is under chronic emotional stress and whose adrenal glands are constantly overworked, their cortisol production is already high and their ability to produce adrenaline has been largely exhausted. If you add a lot of strenuous exercise into the mix, the result is more cortisol production. As the cortisol levels increase, there is a greater and greater tendency to store fat in the lower abdomen.
Also interesting - a scientific study of high cortisol levels in women and the storage of fat: www.ohsu.edu/.../menopausal060605.cfm
Interesting hypothesis.One confounding factor is that"moderate"exercise decreases perceived stress and so would lead to decreased cortisol levels.Very strenuous exercise does increase cortisol levels though.
