Does fat weigh more than muscle, or does muscle weigh more than fat? While it seems common knowledge that muscle weighs more, that's not quite right. The answer depends more on the volume of each.
 
Consider the trick question: "What weighs more, a pound of feathers or a pound of bricks?" The answer, of course, is neither. A pound is a pound, regardless of the material. However, that pound of feathers will look bigger and fluffier than a compact pound of bricks.
So, while we're talking about the weight of muscle and fat, the root of the question is really body size and body composition. While it should be said, first and foremost, that body size or weight is not necessarily an indication of health, there is some truth behind the saying that muscle weighs more than fat.
 
You can be slimmer at a heavier weight than someone lighter, depending on how much non-fat mass (muscle, bones, and organs) you have in proportion to fat mass. Here's what you need to know.
 
 
Does Muscle Actually Weigh More Than Fat?

The short answer: Yes, muscle does weigh more than fat—by volume. The muscle will weigh more if you take a bowl of fat and compare it to a same-sized bowl of muscle.
 That's the simple answer. But much more goes into that question, mainly how your body responds to these two tissues.
 Muscle weighs more than fat because it's denser, said Joel Seedman, Ph.D., neuromuscular physiologist and owner of Advanced Human Performance in Suwanee, Ga. If you hold a fistful of muscle, it will weigh more than a fistful of fat because you technically have more compact tissue in your hand.
 
The catch: That number on the scale shouldn't matter here because the benefits of having more muscle tissue in the body outweigh having more fat tissue.
 
How Having More Muscle Affects Your Health?

Muscle is a star player in keeping your body happy and healthy long-term for several reasons. 
For starters, lean muscle mass can help manage blood sugar, keeping Type 2 diabetes at bay. A 2017 study published in PLoS One found a negative association between muscle mass and Type 2 diabetes—specifically, higher muscle mass meant a lower chance of developing the condition."The number one consumer of blood sugar in the human body is skeletal muscle," So, the more muscle you have, the greater your potential to stabilize your blood sugar. 
As a bonus, the blood sugar-regulating effect is instant and lasts after exercise. So if you do a workout today, your muscles will utilize blood sugar better over the next 72 hours, Church said. Also, as you age, you'll want a healthy amount of muscle rather than fat.
Lastly—and least importantly, in terms of health—the muscle density might cause it to weigh more, which also means it takes up less space in the body. "If someone gains 10 pounds of muscle, a lot of times they'll barely notice that on their body," Seedman said,"whereas, if you gain five or 10 pounds of fat, you definitely notice that."
 
Bioelectrical Impedance Scales

If you want to get a sense of how much body fat versus lean muscle mass you're carrying, consider a bioelectric impedance scale (also called a bioimpedance scale). Many devices that use this technology look like ordinary bathroom scales, but they measure your body composition through electrical impulses.
 
Don't worry; you can't feel it.
 
The downside is that bioelectric impedance scales can be hard to calibrate for accuracy, as any change in water weight (say, if you're dehydrated or have an illness) from one reading to the next may throw off the numbers. But they can give you a good general idea.