I hear and read of people who are exercising to lose weight and boasting about the amount of work they do at the gym all the time, whether it is a tweet, over-heard between friends, or a Facebook post. Things such as “just finished Insanity, Pilates, and Weights, great 2-3 hour workout!” What they really should be saying is “wow, I over-trained so much that my body is going to store fat and break down my lean calorie burning muscle.” (insert sad face icon here)
Newsflash! Exercising for too long at one time does more harm than good.
Once your weight loss or muscle building workout reaches 45-60 minutes your body starts to think that it is under threat and must respond to preserve and protect itself from this intense activity. The way the body will respond is to starting secreting the hormone Cortisol in response to this perceived threat (long intense exercise). Cortisol, for those who think lifting weights and running after an Insanity cardio session is a great idea, is a hormone that is associated with stress, fat storage and weight gain!
Marathon runners are a fine example of athletes who push their bodies too far for too long – they are lean like a scarecrow and generally are not an example of what a good looking healthy person is. If weight loss is all that matters it is one thing, but if you want to preserve or grow muscle and look like a generally healthy person, it hurts not helps. This is because overtraining will also have your body looking for alternate sources of energy to survive the extended stress you are putting it through. The body will keep fat stored for later use and begin looking at amino acids – necessary building blocks of muscle – and converting them to an energy source. What happens here is that all at once your body is releasing Cortisol (a “storage” hormone), and breaking down muscle for their amino acids.
It is a double whammy of fat storage AND muscle loss all because you had the grand idea and good intentions to train intensely for 2+ hours in order to lose weight. When this happens your body requires extended rest to prevent loss of appetite (leading to further muscle loss), weakened immune system and susceptibility to injury.
If you feel the absolute need to stay in the gym for more than an hour the safest way would be to exercise with intensity for 45-60 minutes and follow that with slow low volume cardio. Coupling intense aerobic exercise with intense anaerobic training is simply Insanity.