The number of sit-ups required to lose 30 pounds in one month depends on personal weight and the duration and intensity of the exercise. A 150-pound individual burns approximately 10 calories vigorously doing sit-ups for one minute.
A person loses weight when they burn more calories than they ingest. Through a combination of diet and regular exercise, losing 1 to 2 pounds per week is both healthy and sustainable, according to the CDC. One pound of body weight equals about 3,500 calories, so healthy weight loss requires a caloric deficit (burning more calories than taking in) of 500 to 1,000 calories daily.
Although sit-ups can be a good core workout, doing sit-ups only is not an effective weight-loss exercise. Vigorous aerobic exercise like swimming or playing tennis burns more calories per minute.