Sit-ups will not get rid of belly fat because you cannot get rid of fat in a certain area just by exercising the muscles underneath that fat. You will lose the most belly fat by exercising intensely in any sport ( Medicine and Science in Sports and Exercise, November 2008). Three groups of overweight, middle-aged women who suffered from Metabolic Syndrome completed 16-week programs of: (1) continuing their existing levels of activity with no change; (2) low-intensity exercise training five times a week at a level that did not cause breathing hard; and (3) high-intensity exercise training with three days a week hard enough to become short of breath and two days a week at an intensity not becoming short of breath. Cat scan X rays and air displacement plethysmography studies showed that the high intensity exercisers lost belly fat, both underneath their skin and inside their bellies. The low-intensity exercisers lost no measurable belly fat.
Storing extra fat in the belly causes people to become diabetic. Full fat cells produce hormones that prevent the body from responding to insulin so that blood sugar rises too high, causing sugar to stick to cells and damaging cells anywhere in the body. Those who store fat primarily in the belly are the ones most likely to suffer high rises in blood sugar. If you store fat primarily in your belly, have high blood levels of triglycerides and sugar, and low levels of the good HDL cholesterol, you meet the definition of Metabolic Syndrome and the odds are that you are diabetic, or will become diabetic soon. You are likely to suffer a premature death unless you make major lifestyle changes: lose weight, exercise, avoid refined carbohydrates (except during exercise), and make sure you get enough vitamin D.
Exercise can cause heart attacks in people with blocked arteries, and intense exercise increases the risk. Almost 80 percent of diabetics die of heart attacks. Check with your doctor before starting a new exercise program or increasing the intensity of your existing program.