Transparency is extremely important to us, so we are letting you know that we may receive a commission on some of links you click on from this page. See our disclaimer.

How many times have we said to ourselves: Well, I'll eat that slice of cake and just burn it off at the gym later?

Indeed, it's an age old debate: Which matters more for weight loss — diet or exercise? Now the Mayo Clinic weighs in.

In a piece titled, “Exercise for weight loss: Calories burned in 1 hour,” they write: “Being active is an important part of any weight-loss or weight-maintenance program. When you're active, your body uses more energy (calories). And when you burn more calories than you consume, you lose weight.”

“Because 3,500 calories equals about 1 pound (0.45 kilogram) of fat, you need to burn 3,500 calories more than you take in to lose 1 pound. So if you cut 500 calories from your diet each day, you'd lose about 1 pound a week (500 calories x 7 days = 3,500 calories). There are other factors that can influence this equation. Because of changes that occur in the body over time, calories may need to be decreased further to continue weight loss.”

So what's Mayo's answer to the key question?

Writes Mayo: “Both are important. However, while diet has a stronger effect on weight loss than physical activity does, physical activity, including exercise, has a stronger effect in preventing weight regain after weight loss.”

The piece offers a quick synopsis of the U.S. Department of Health and Human Services “2008 Physical Activity Guidelines for Americans“:

• “Aerobic activity. Get at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity. However, to effectively lose or maintain weight, some people may need up to 300 minutes a week of moderate physical activity. You can do a combination of moderate and vigorous activity. The guidelines suggest that you spread out this exercise during the course of a week, and sessions of activity should be at least 10 minutes long.”
• “Strength training. Do strength training exercises at least twice a week. No specific amount of time for each strength training session is included in the guidelines.”

More info can be found here from the U.S. Centers for Disease Control and Prevention.