Crunches and situps can tighten up your abdominal muscles and give you core strength needed to perform other exercises. However, the American Council on Exercise and the American College of Sports Medicine indicate that crunches alone won't make you lose weight or give you a flat belly. To burn excess body fat, you must engage in aerobic activity, such as brisk walking, jogging or cycling.
Spot Training Myth
Spot training away fat is a myth, according to ACE. Crunches are often promoted as a way to get a slim, trim belly. ACE notes that the only way that you can reduce extra fat by doing crunches or another type of spot-training exercise is to do them frequently and vigorously enough so that fat is burned all over your entire body --- not just your problem spots. Performing crunches will tone the muscle underneath subcutaneous fat, but it's not likely that you can sustain them at an intensity needed to burn body fat.
What Works
Crunches probably won't make you lose weight. What will is regular aerobic activity and strength training along with a healthy diet. If you want to maintain your current weight or lose a little weight, put in between 150 and 250 minutes of moderate-intense aerobic activity throughout the week, according to the ACSM. But if you want to really burn away pounds, get more than 250 minutes of moderate-intense aerobic activity weekly. Perform strength-training exercises at least twice a week, too --- this builds lean muscle. ACE explains that body fat tends to disappear last in places where you notice it the first. In men and some women, this is typically the belly. For women --- as well as some men --- fat on the thighs, hips and buttocks is more obstinate.
Study
If you want to lose weight and belly fat, exercise intensity can matter. A study published in the November 2009 issue of "Medicine & Science in Sports & Exercise" suggests that high-intensity exercise is better for improving body composition. Twenty-seven obese women were divided into three groups, seven of which made up a control group. Eleven of the women engaged in low-intensity exercise five days weekly, while nine engaged in low-intensity exercise two days of the week and high-intensity aerobic exercise three days a week. After 16 weeks, researchers found that the group that exercised at a higher intensity decreased both subcutaneous and visceral belly fat. However, lead researcher Arthur Weltman, Ph.D., told the ACSM that exercise intensity should be recommended based on individual capabilities. Simply getting 30 minutes of moderate intense aerobic activity at least five days a week gets you on the right path.
Consumer Beware
The spot training myth is only one of many to which those new to exercise may fall prey. The ACSM urges you to beware of other unrealistic weight loss claims. Steer clear of machines and devices that purport to work your "fat-burning zones" with very little effort. Vigorous exercise performed for only a few minutes won't do the trick, either; you need to exercise at a specific frequency and duration to see results. Nor will exercise machines that purport to burn twice the number of calories than you would on a treadmill or elliptical.
References
- American Council on Exercise; Why is the Concept of Spot Exercising Considered a Myth?; Jessica Matthews; September 2010
- American College of Sports Medicine; Consumers Should Exercise Caution on Fitness Machine Claims; September 2009
- American College of Sports Medicine; ACSM Position Stand on Physical Activity and Weight Loss; January 2009
- "Medicine & Science in Sports & Exercise"; Effect of Exercise Training Intensity on Abdominal Visceral Fat and Body Composition; A. Weltman, et al.; November 2009
- American College of Sports Medicine; High-Intensity Exercise Best for Improving Body Composition; October 2008
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