By YouBeauty.com Editors
The Scientist: James Graves, Ph.D., professor of exercise and sport science and dean of the College of Health at the University of Utah.
The Answer: Sadly, there's no such thing as spot reducing fat (short of, say, liposuction). You could do crunches until the cows come home, but if you've got too much belly fat overtop, no one's going to see your six pack.
Fat loss is systemic, meaning it happens throughout your whole body, not one trouble spot at a time. To reduce fat in any one place, you really need an old-fashioned more-calories-out-than-in approach that addresses body fat as a whole. That means a well-rounded exercise program, with a combination of aerobic endurance activities and strengthening exercises all over your body, plus a healthy diet.
Physiologically, the goal is to simultaneously shrink your fat cells and increase the size of your muscle cells. Crunches won’t burn calories like running, swimming, or cycling will, so you can't count on them to reduce fat mass. That said, they will get you better abs. Muscle building, unlike fat burning, is done muscle by muscle. Not only will crunches increase your abdominal muscles' strength, they also tone your muscles, so that once you do reduce the size of the fat cells around your middle, you'll see a well-defined set of abs underneath.
What's more, your abs, along with your obliques and lower back muscles, make up your core, so strengthening these muscles increases your stability, minimizes many types of back pain and improves your posture.
Aim for 20 minutes of aerobic exercise at least three times per week, and strength training activities (including, but not limited to, ab work) at least twice a week.