Does muscle weigh more than fat? Discover why this is a myth and the real relationship between fat and muscle. You’ll also learn how to take inventory of your health, so you can get started on your goals.

By Michael Ormsbee, Ph.D., Florida State University

Comparing Fat to Muscle Weight

Some health “gurus” insist that muscle weighs more than fat. As it turns out, this popular claim is actually a myth.

It’s like saying that one pound of bricks weighs more than one pound of feathers. But here’s the difference: Muscle has more density than fat. This is the key to understanding why two people can weigh exactly the same at the same height, but look entirely different.

In the underwater weighing method for measuring body composition, the more muscle mass someone has, the more dense they are, and the more they weigh underwater. However, the more fat mass someone has, the less dense they are, and they more likely they are to float in water.

Let’s compare five pounds of fat with five pounds of muscle. They weigh exactly the same, but the muscle is about ⅓ or ½ smaller than the fat because of its increased density.

So, don’t be fooled by this myth any longer—when you add muscle, you might weigh the same, but you could look entirely different.

Setting Health and Fitness Goals

When tracking your progress in any diet or fitness plan, you first need to understand the difference between body composition and weight.

“Your body composition is a far better indicator of health, success, and even performance than simply body weight measured on your bathroom scale,” said Dr. Michael Ormsbee, Associate Professor in the Department of Nutrition, Food, and Exercise Sciences at Florida State University.

Take a good self-inventory. Do you feel healthy? Are you ever gasping for breath after activities that you used to do easily?

Do you have any noticeable android or central fat levels? Has your doctor told you of any health issues due to excess body fat?

Answer these questions and then set challenging, but realistic goals.

For a very active person, the goal could be to complete a 10K or half-marathon race, or maybe to do a set number of unassisted push-ups or pull-ups. For these sorts of people, a lower percent body fat will be reasonable with their overall lifestyle.

For others, the goal may be just to keep disease at bay, lose a small amount of weight, or to maintain their current weight. Remember, your goal may not be the same as your best friend’s; it will always be personal and specific to you.

Once your goal is determined, and you have a plan to get there with the help of a professional, then an ideal body fat level can be paired with that goal.

This article was edited by Kate Findley, Writer for The Great Courses Daily.

Dr. Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his M.S. in Exercise Physiology from South Dakota State University and his Ph.D. in Bioenergetics from East Carolina University.