Losing pounds requires a calorie deficit, meaning that you burn more than you consume. While it may seem as if 100 sit ups a day may lend itself to the six-pack of your dreams, solely doing sit ups will not help you lose weight. You can have rock solid abs beneath layers of fat, but melting the fat will require more than just spot training the area. To lose 1 to 2 lbs. per week, which is the healthiest rate of weight loss, according to MayoClinic.com, you must include proper diet and exercise.
One pound is the equivalent of 3,500 calories. To lose 1 lb. a week, you must eliminate 500 calories per day through exercise, diet, or a combination of both. According to Csgnetwork.com, a calorie burn calculator, a 145-lb. person doing 5 minutes of vigorous sit ups will burn only 33 calories. In one week, that's only 231 calories -- not even half of what you should be burning per day.
If you were to only do 100 situps every day for one week, you would not lose weight, even if you were coming from a very sedentary lifestyle. If you were to do 100 situps and then alter your diet by eliminating 450 calories per day, then you would most likely see the scale drop 1 lb. by the end of the week. Continue to include situps in your exercise regimen, but aim to burn more calories by exercising longer and harder.
If weight loss is your goal, consider changing your activity level. Exercising 30 minutes most days of the week will result in additional calorie burn and an increased chance of weight loss. That same 145-lb. person could burn nearly 400 calories with 30 minutes of fast cycling. If performed several days of the week, coupled with eliminating a mere 100 calories per day, you could be on track to lose 4 to 5 lbs. in a month.
Dieting doesn't always mean embarking on a fad diet like the Atkins or the South Beach Diet. Eating several small meals per day will boost your metabolism, and filling your diet with protein, fiber and healthy fats will help keep you satiated. If you are burning 300 calories with your exercise plan, begin looking for ways to get rid of 200 calories from your diet. It could be as simple as eliminating a can of soda, a handful of chips, or that extra tab of butter you spread on your toast.