Walking up stairs expends calories, which burns off fat.
To lose extra fat, you need to burn more calories by exercising. You can't "spot reduce" and eliminate only your belly fat. The only way to shed your belly fat is to lose fat all over. Walking up the stairs is an aerobic exercise that burns calories, so it will help you lose belly fat if you do it as part of a regular exercise program.
How You Lose Fat
According to Mayo Clinic, physical activity is a must if you want fat-loss results. Exercise expends calories, which means burning fat. Expending more calories than you consume leads to fat loss. One pound of fat equals 3,500 calories, so you need to burn an extra 3,500 calories to lose a pound. Eating a healthy diet with appropriate portion sizes typically helps lower your calorie intake, or you can keep track of the calories you consume and the calories you burn to make sure you create a deficit.
Stairs Burn Calories
Dr. Bryant from the American Council on Exercise said in an interview for an article for "The New York Times" that walking up stairs at a moderate intensity burns five calories a minute for a 120-pound person and nine for a 180-pound person. Climbing stairs on a stair treadmill for an hour burns about 660 calories for a 160-pound person, according to Mayo Clinic. For comparison, that's 350 more calories than you would burn walking in one hour, but you would burn about 200 more if you were running or jumping rope instead. Running upstairs instead of walking multiplies the caloric burn and the cardiovascular benefit, according to Dr. Bryant.
Stairs Build Muscle
Walking up the stairs builds muscle, which plays an important role in fat loss. The stairs work your quads, hamstrings, glutes, hip flexors and calves all in one workout. Although stairs only build your leg muscles, you lose belly fat efficiently because you're working some of the largest muscles in your body, including your glutes, quads and hamstrings. Exercises that build mass on your large muscles burn more calories while you're doing them and afterward. The more muscle mass you have, the faster your metabolism is, or the more calories you burn even at rest. By building muscle, walking up stairs also has long-term effects on fat loss by increasing your metabolism.
How To Do It
Increase your intensity by running up stairs instead of walking. Do intervals walking up then running up, or running up and walking down. This will burn more calories and help you lose belly fat faster. To avoid plateaus in fat loss, you not only want to increase your intensity as you improve, but also add variance to your exercise program. You should do three to six cardio exercises per week for fat-loss results, but not all of them should be stair climbing. Do strength-training exercises at least three times a week to build muscle mass. Your abs are one of your largest muscle groups, so you'll build more muscle and burn more calories, and defined muscle will start to replace your belly fat.