Ask the Dietitian: How Can Muscle Weigh More Than Fat?

Trinh Le, MPH, RD
by Trinh Le, MPH, RD
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Ask the Dietitian: How Can Muscle Weigh More Than Fat?

Chances are someone told you “muscle weighs more than fat” as an encouraging explanation for why you sometimes gain weight after adding strength training to a fitness routine. It’s also cited as a reason for why some people hit a weight-loss plateau. But a pound of muscle can’t weigh more than a pound of fat, so what’s the deal here?

MUSCLE VERSUS FAT

It’s important to look at the saying “muscle weighs more than fat” in context. It’s not referring to weight, but rather, the difference in density between these two tissue types. Muscle is denser, weighing more per unit of volume compared to fat. Simply put: Muscle takes up less space than fat on any given body frame. This is why fitness enthusiasts like to improve their overall muscle-to-fat ratio rather than focus on their total body weight.

HOW BODY WEIGHT CAN BE DECEIVING

You can actually weigh the same and steadily be gaining body fat over time. Past age 30, muscle loss occurs at 3–5% per decade, accelerating to more than 15% per decade after age 50. Bone, another weighty tissue, also decreases in density due to aging. That’s why experts recommend strength training at least twice per week to help offset aging-related changes.

THE BENEFITS OF BUILDING MUSCLE

  1. It creates a leaner physique.
    Muscle is more compact and holds its shape better than fat.
  2. It boosts metabolism. 
    Muscle burns slightly more calories than fat and having more muscle mass is linked to lower insulin resistance since skeletal muscle can take in extra glucose when blood sugar levels are high.
  3. It improves mobility. 
    Muscle powers every activity you do, helping you achieve more physical feats.

HOW TO MAINTAIN MUSCLE MASS DURING WEIGHT LOSS

Muscle is denser and may not show up favorably on the scale, but you should strive to preserve — and even build more — muscle as part of your weight-loss plan. Sadly, weight comes off as both fat and muscle. As rule of thumb, one quarter of your weight loss comes from lean (Read: muscle) tissue. You can shift this ratio in your favor by:

  1. Eating more protein. 
    The recommended daily allowance (RDA) for protein is 0.8 grams per kilogram of body weight, but you can benefit from going higher if you’re cutting calories for weight loss. Research recommends protein intake at 1.25 times the RDA for sedentary individuals and 1.5 times the RDA for active individuals.
  2. Exercising in addition to improving your diet. 
    You may know resistance training (aka: weightlifting) helps build and preserve muscle even as you lose weight. Endurance exercise counts, too. Two studies of middle-aged adults found brisk walking for about one hour daily helped preserve more lean muscle mass during weight loss compared to diet-only plans.
  3. Keeping an eye on your body-fat percentage. 
    It can be helpful to track progress quantitatively. Body-fat percentage indicates what percent of your total body weight is coming from fat. To get an idea of your number you can use a smart scale. It uses “bioelectrical impedance,” or a stream of electricity, to approximate body-fat percentage.

THE BOTTOM LINE

Don’t be discouraged if you’re putting in the hard work to eat better and exercise more but aren’t seeing much movement on the scale. Body weight paints an incomplete picture of your health and physique. Instead, focus on signs of progress that aren’t just a number on the scale such as how much energy you have, how much farther you can run and how well your clothes fit.

About the Author

Trinh Le, MPH, RD
Trinh Le, MPH, RD
Trinh is a registered dietitian by day, blogger at Fearless Food RD by night. She loves helping folks develop a better relationship with food, which includes lots of cooking, eating and learning about nutrition. When she’s not snapping mouthwatering shots of (mostly) healthy food, you can find Trinh HIIT-ing it at her local gym. For more, connect with her on FacebookInstagram and Pinterest.

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10 responses to “Ask the Dietitian: How Can Muscle Weigh More Than Fat?”

  1. Avatar Rinkal Patel says:

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  2. Avatar Carson E Klein says:

    Okay so on the initial comment made… a pound of muscle equals a pound of fat, but which takes up more space. A brick weighing say 3 lbs or 3 lbs worth of straws? They may both weigh the same, but the straws are spread out and taking up more space. The brick is more condense while the straws have empty space and stack.

    Also. I’m noticeably “smaller” than many of my friends though I actually weigh more or the same.

  3. Avatar Nhonami Formi says:

    Obviously, if you compare 1 pound of two substances they will weigh the same. If you’re going to do a weight comparison, the equalizing factor should be something other than weight. If someone were to compare a cubic inch of fat and muscle, the muscle would most definitely weigh more. This is not a myth it is an observable fact.

    • Avatar Karen Eisenbraun says:

      Yes, thank you! The “pound of muscle weighs the same as a pound of fat” argument needs to die. Although in the next section she does clarify that muscle weighs more per unit of volume compared to fat. This is the real issue … weight by volume.

  4. Avatar Melanie says:

    What is a healthy body fat percentage? For example, I’m a 34 year old female with a body fat percentage of about 29%. What should I be shooting for?

    • Avatar DaBoss says:

      Women: 20-40 yrs old: Underfat: under 21 percent, Healthy: 21-33 percent, Overweight: 33-39 percent, Obese: Over 39 percent. 41-60 yrs old: Underfat: under 23 percent, Healthy: 23-35 percent, Overweight : 35-40 percent Obese: over 40 percent.
      You are well in the healthy range Melanie.

      • Avatar Kaitlyn says:

        Women can easily have down to 14% body fat if they’re athletic. That’s not an unhealthy or “under fat” amount.

  5. Avatar Kathy Kemp says:

    Now can we ditch the stupid BMI chart once and for all and use a more complete picture of a person’s health?

    • Avatar Cathy Carroll Rampasard says:

      The BMI chart is the only thing my doctor looks at. He doesn’t even factor in that I am eating a healthier diet than I ever have, I work out with a personal trainer 4X a week & my lab values are excellent!

  6. Avatar Kaitlyn says:

    It’s frustrating that a dietician is saying that lean mass = muscle. It’s not. It includes muscle, yes, but it also includes water, blood volume, etc. When you lose weight you also lose water and blood volume, not necessarily muscle. Putting out false information like that makes people who rely on bioelectrical impedance think they may have lost just muscle if they lose weight that may be mostly water and suddenly their lean mass % goes down.

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