Is Exercise Necessary for Weight Loss?

Answer: Yes. People who are physically active are far more likely to lose weight and keep it off.

You probably read headlines this year that screamed: “Why Exercise Won't Make You Thin!” Those stories were based on a controversial Public Library of Science study that showed women who exercised regularly for six months were no more likely to lose weight than women who didn't work out at all.

How could that be? We all know that exercise burns calories; an hour on the treadmill torches 300 to 500.

Heres the deal: Much of what was written about the study was misleading, says its lead author, Timothy Church, MD, director of preventive research at Pennington Biomedical Research Center in Baton Rouge, Louisiana. The study didn't focus on calories; all participants followed their regular diets.

What the study showed, Dr. Church says, is that exercise alone, especially if you eat poorly, may not help you lose weight. “Exercise doesn't give you carte blanche to eat whatever you want,” he says. “People think an hour on a treadmill burns off a whole chocolate cake. In reality, it's half a slice.”

Its true that exercising without dieting—or worse, piling on calorie-rich food just because you worked up a sweat—wont lead to weight-loss success, agrees Susan Roberts, PhD, professor of nutrition at Tufts University. But dieting without exercise isn't the answer, either.

In fact, The National Weight Control Registry, a group that follows how 6,000 people have lost weight and kept it off, found that the most successful participants work out at least 30 minutes every day. The truth: Combining smart dieting and regular exercise offers the best chance to reach your weight-loss goals.

The workouts that work hardest:

Interval workouts—short bursts of high-intensity exercises—along with strength training are best for weight loss. Some of our favorites:

At the gym

• Boot camps have a good mix of cardio and circuit training.
• Spinning—with its climbs, sprints, and cooldown segments—is a classic interval workout.

At home

• The Jillian Michaels 30 Day Shred DVD ($14.98) combines fast-paced kickboxing, strength training, and great ab work.
• The Results Fitness: 10 Days to a Better Body DVD ($14.98) alternates between intense cardio and sculpting moves.

DIY

Walk, run, or bike for 1 minute at a moderate pace, then for 1 minute at a higher intensity (get breathless); alternate for 20 minutes.