Diet or Excercise: Which Is More Efficient For Weight Loss?

"Our beliefs guide our actions," says Brent McFerran, PhD, an assistant professor at the Ross School of Business at the University of Michigan.

As you might expect, people's weight-control theories affects their food choices. In two studies, when researchers offered participants unlimited chocolate, the people who said they think staying active (excercise) is key to maintaining a healthy weight ate more.

In another study, researchers asked a total of more than 1,200 people in the U.S., Canada, China, France, and South Korea about the main factor that makes people overweight. They also took participants' height and weight measurements to calculate their BMIs. Interestingly, those who said it's most important to stay active to prevent obesity had higher BMIs than the people who said eating right is the key to weight control.

Think about it: If you think exercise is the key to weight control, you might move more and focus less on what you eat.

On the flip side, if you believe that eating a healthy diet is the best way to maintain your weight, you might worry less about exercise—but closely watch what you eat. And that's smart, especially because most people grossly underestimate the amount of calories they consume, says McFerran.

"If we eat a 3000-calorie lunch, nearly no one has enough free time in the rest of the day to exercise it off," he says.

Luckily, McFerran's best advice for weight control doesn't take much time: Steer clear of foods that are high in calories, and trade large plates and bowls for smaller ones to ensure you fill them with more restrained portions.

The problem is that many people think they can work off extra pounds—but there's a ton of scientific evidence to support the fact that changing your diet is a more effective way to drop weight, says McFerran.

While exercise can definitely support weight loss—and make you feel awesome, among other benefits—people tend to overestimate the amount of calories they burn while working out and compensate for the extra activity by eating more, says McFerran.

That said, you should probably hold onto your gym membership, too. Although it's tough to slim down with exercise alone, staying active does help with weight control—and it's absolutely crucial for your health, says Keri Glassman, RD, a Women's Health weight loss expert.

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