Most individuals would have to perform over 50,000 sit-ups to lose 4 pounds. AZCentral explains that vigorous calisthenics, which includes sit-ups, burn about 430 calories per hour for a person weighing 130 pounds. Because each 3,500 calories burned equals 1 pound of lost weight, it takes approximately 28 hours of vigorous sit-ups for a 142-pound person to lose 4 pounds. At 30 sit-ups per minute, that is over 50,000 sit-ups.
While doing 50,000 sit-ups would certainly burn calories and tone stomach muscles, it probably isn't the best way to approach losing weight. For most people, weight loss is best achieved through a combination of diet and exercise, particularly cardiovascular exercise, such as running, swimming, biking and walking. These types of exercise generally burn more calories than muscle-building exercises, such as sit-ups and push-ups.
According to WebMD, by taking between 1,050 and 1,200 calories per day and exercising for an hour a day, it is possible to lose 3 to 5 pounds in the first week of a weight loss regimen. Continued weight loss depends on regular exercise and good eating habits. A healthy balance of vegetables, fruits, whole grains and lean meats generally provides all of the nutrients that a person needs. Avoid overeating as well as high-caloric snack foods and desserts, especially sugary drinks such as soda.