It is often assumed that the fewer calories we eat and the more exercise we do, the greater the weight loss results; however, human metabolism is a little more complicated than that.
While it may be the case that if you have many kilograms to lose, a dramatic drop in calorie intake, coupled with extra exercise, will result in a relatively large weight loss. However, once if you are looking at losing a small amount of weight – say 5kg to 10kg – the combination of chronic calorie restriction with high amounts of activity, can actually slow down fat metabolism.
Muscles require carbohydrate to burn fat. If a muscle is expected to exercise intensively, but has insufficient carbohydrate available to it to effectively burn fat, your metabolic rate will be reduced as a way for the body to conserve energy, rather than burn the extra carbohydrate and fat. And this is the likely reason that individuals who train excessively, and who constantly restrict their carbohydrate intake, are not as lean as they would perhaps like to be.
The easiest way to understand this scenario is thinking of carbohydrate as the fuel for a fire – a muscle without carbohydrate when it is exercising can be likened to a fire that does not have much wood: it still keeps burning but not in the raging way it does when it is fully stoked.
So, if you are a big trainer, and training for more than an hour a day, and still not leaning up, chances are you need a little more carbohydrate to stoke your own fire, in order to become as lean as you want to be.
Article by nutritionist, Susie Burrell