I have been involved with fitness and nutrition for a number of years. It is my passion.
There is one thing (well more than one, …fat loss supplements, over supplementation and whey protein) that is like nails on a chalkboard to me, and that is the practice of over prescribing cardio by trainers that have no idea about human physiology and hormone balancing.
I am referring to any cardio session exceeding 30 minutes at a steady state or any cardio session exceeding 60 minutes (typical of group exercise classes).
It is time to come into the 21st century. It is has long been proven that beyond a doubt cardio chronically shuts down the production of thyroid hormone, T3, and increases other stress (fat storing) hormones, especially in women.
T3 is the body’s regulator of metabolism; it controls how the body uses foods…burns calories. When T3 levels are normal, the body burns enough energy to stay warm and muscles function at moderate efficiency. Too little T3 and the body stores fat around the midsection, almost regardless of physical activity. So the old school of thought: more exercise, less calories will simply cause increased fat storage and further depressed levels of T3.
Think about this way: the body is a responsive, adaptive machine, evolved for survival. If you are running on a regular basis, the body senses excessive energy expenditure and adjust to compensate. Remember, no matter what dreamy nonsense we invent about how we HOPE the body works; its endgame is ALWAYS survival. When the body is in that survival mode it will not burn calories. So if you are wasting energy running, (or swimming, spinning or other forms of steady state, or long intervals of cardio) the body reacts by slowing down metabolism to conserve energy.
In addition to fat storage, you will start to lose lean muscle mass. That is correct, no more muscle, because too much steady state cardio or too much cardio at one time triggers the loss of muscle through the release of cortisol. The release of cortisol also causes the loss of bone density, and ultimately the loss of strength. When sewn together these events cause a symphony of fat gain. After a month or so of 20 plus hours of cardio a week, fat burning becomes slower and slower. To make matters the frustrated female will cut calories further and up her exercise.
The “cardio-craze” and this form of insanity is on my hit list and I am determined to spread the truth. Remember a great body always starts in the kitchen and a correct exercise program specific to your goals. Please make sure that whoever or wherever you are getting your fitness advice from has a strong understanding of exercise physiology as well as human physiology.