Brace yourself for some bad news: The whole idea of spot reduction is a myth, meaning you can't exercise a body part to lose fat from just that part of your body. So no matter how many sit-ups you do, they won't magically melt fat off your belly.
That doesn't mean you shouldn't do abdominal exercises. As the Mayo Clinic explains, building strength and endurance in your core muscles helps improve your balance and athletic performance and ultimately helps you reach your athletic goals. And those sit-ups can be one component of a balanced diet and exercise program to help you slim excess fat from everywhere, including your belly.
No, sit-ups won't spot-reduce fat from your belly. But they can be part of a comprehensive exercise and diet program to help you trim excess fat from all over your body — including your belly.
Science Says 'No'
Two particularly noteworthy studies directly negate the idea of using abdominal exercises, like sit-ups, to "burn" abdominal fat. The first, published in the September 2011 issue of the Journal of Strength and Conditioning Research, studied a group of 14 participants through a six-week training period.
At the end of that period, the subjects who'd done abdominal exercise did increase their muscular endurance when compared to the control group. But they didn't lose abdominal fat when compared to the control group.
Another study, published in the March-April 2015 issue of the Journal of Manipulative and Physiological Therapeutics, involved 40 overweight and obese women. During the 12-week study period, half the participants combined a diet with abdominal resistance training, while the other half followed diet only.
At the end of the study period, both the control group and the group that did abdominal resistance training lost weight. But there was no significant difference in weight lost or in specific measurements of subcutaneous belly fat and waist circumference.
What Does Work?
So what should you do to burn belly fat? To lose fat from all over your body — including your abdomen — you must establish a negative calorie balance, or burn more calories than you take in.
There are two ways to achieve that negative calorie balance — lowering your calorie intake and increasing your physical activity. As the Centers for Disease Control and Prevention notes, weight loss of 1 to 2 pounds per week is both safe and sustainable, while faster rates of weight loss are often neither. That rate of weight loss works out to burning 500 to 1,000 more calories per day than you consume.
There's a catch: Don't starve yourself. In fact, Harvard Health Publishing notes that unless you're under a doctor's supervision, you shouldn't bring your daily calorie intake below 1,200 calories (for women) or 1,500 calories (for men).
Instead, take a hint from subjects being followed by the National Weight Control Registry. According to this ongoing study of more than 10,000 people, the vast majority who lost weight and kept it off did so by adjusting both physical activity and diet.
So, while you can lose weight with a modest reduction in your calorie intake, you'll see faster results — and greater health benefits — if you increase your physical activity too.
According to estimates from Harvard Health Publishing, if you weigh 185 pounds, you'll burn about 133 calories in a half-hour of general resistance training, which can include sit-ups and other core exercises.
You'll burn more calories if you weigh more and fewer calories if you weigh less. Exercise intensity also plays a role: The harder you work out, the more calories you burn. That same reasoning applies to cardiovascular workouts, which are often the most efficient calorie burners.
Just a few cardio workouts to consider include aerobics classes, walking, running, swimming, cycling, dancing, skiing, playing sports like tennis or throwing a flying disc, kayaking, canoeing, hiking and stand-up paddleboarding. If you find something you enjoy for its own sake, it'll be that much easier to incorporate into long-term lifestyle changes to lose excess fat from everywhere, including your belly.
- Journal of Strength and Conditioning Research: "The Effect of Abdominal Exercise on Abdominal Fat"
- Journal of Manipulative and Physiological Therapeutics: "Effect of Abdominal Resistance Exercise on Abdominal Subcutaneous Fat of Obese Women"
- Mayo Clinic: "Core Exercises: Why You Should Strengthen Your Core Muscles"
- National Weight Control Registry: "NWCR Facts"
- Centers for Disease Control and Prevention: "What Is Healthy Weight Loss?"
- Harvard Health Publishing: "Calorie Counting Made Easy"
- Harvard Health Publishing: "Calories Burned in 30 Minutes for People of Three Different Weights"