In aerobic exercise when subjects are exercising at moderate to low percentages of their maximum – as in walking, jogging or slow swimming almost all the energy comes from fat. Only if the rate of exercise is speeded up does muscle bring in glycogen and glucose fuels so in walking or jogging fat is being utilised directly.
Burning fat.
Exercise has a degree of ‘after-burn’ effect. It triggers the release of catecholamine, which may maintain a higher rate of metabolism for an hour or two after exercise. After vigorous exercise this effect may last even longer.
If a person eats 100kcals less each day (the equivalent to a slice of bread with margarine and jam) and expends the same amount in exercise (15-20 minutes of moderate walking) then in a year the calorie deficit would amount to 18.1lbs of fat.
This is the way to think about fat loss – long term and gradual. Severe calorie restriction by crash dieting can depress the metabolic rate by as much as 45%, so much less food is needed. Such a diet tends initially to empty the muscle resources of 3-6lbs of glycogen and as each 2lbs of glycogen also stores 6lbs of water, weight loss on a crash diet can be very dramatic indeed for the first few days. But it does not represent fat loss. Glycogen deposits have to be replenished, so all the weight you think you have lost – comes back!
A combination of modest diet and modest exercise is important, partly because most people are disappointed during the early months of an exercise only programme that they do not lose weight quickly, although they may be losing fat! A programme that includes exercise will increase muscle mass (not bulk) including a slightly larger store of glycogen in the muscles, the blood volume will beneficially increase and there will be some increase in bone and tendon, so loss of fat is not always accompanied by equivalent loss in weight.
What you will notice is that the shape of the body will alter. Your body will also become more efficient at burning calories, you will feel better, recover from exertion quicker and you will increase your bodies ability to fight illness.
Fatbuster
