Does Muscle Weigh More than Fat?

One of the reasons I find many runners not lifting is they’ve heard that strength training makes you gain weight. Which often comes from hearing that muscle weighs more than fat.

It’s not surprising that we get confused about this topic because many of us grew up using the scale as a measure of progress with our health and fitness goals.

Weight loss however is not the same as fat loss.

And what most people are truly striving for is fat loss. Let’s look a how the muscle weighs more idea started and what you really need to know about strength training and weight gain.

Does Muscle Weigh More Than Fat?


It’s not true.

If you put 1lb of feathers on a scale and 1lb of rocks, they weigh exactly the same amount…. one pound.

However, what that also illustrates is that density matters.

  • Muscle is denser than fat
  • You can weigh more and be smaller because you have more muscle and less fat
  • Muscle needs less space in the body
  • Muscle burns more calories at rest than fat

One pound of fat takes up 15% MORE space than one pound of muscle.

Again, it is denser therefore someone could actually be smaller and yet weigh more than someone who has less muscle mass. provides a great example of this in the real world. Here she weighs 145 in both photos, showing that the scale isn’t telling the whole story.

This is not to say that one is inherently better than the other! We are simply breaking down the idea that muscle weighs more than fat.

This doesn’t mean that strength training will make you bulky.

In order to bulk up like a body builder, you need to do more than just lift weights.

What does it take to get bulky from strength training?

  • Years of consistent strength training
  • High protein, super high calorie diet (rarely what anyone looking to lean out is eating)
  • Heavy, heavy weight training with a focus on strength
  • When bulking they are actually putting on muscle and fat due to the high volume of food, then they go in to a phase of leaning out, then bulking again
  • Supplements

Why am I gaining weight from strength training?

If you’ve started a new strength routine and are noticing the scale creep up, it’s probably not what you think.

  • The average newbie cannot put on more than 2 lbs of muscle in a month
  • That’s with consistent strength training and enough calories for muscle gain (often not happening with those on a diet)
  • Those who have been strength training for longer can only put on .5 to 1 lb per month

Which means if the number on the scale has gone up 10lbs since you started working out last month, you didn’t pack on 10lbs of muscle.

  • Workouts result in micro-tears and inflammation, the body holds on to water to repair this damage
  • You may be eating more because strength workouts increase hunger levels
  • You may need to add more protein to your diet to help with muscle building, fat loss and muscle repair
  • You may need to increase your daily water intake to ensure you aren’t dehydrated which will also cause water retention

Building muscle may increase your body weight, but you will lose inches off your waist or thighs because it’s helping you to change the shape of your body.

Another great example of how she used strength training to build muscle, which increased the number on the scale, but dropped her overall body fat resulting in the “toned” look that many women are seeking.does muscle weigh more than fat

Worry less about the scale and more about performance.

Or if you’re in to measuring then focus on body measurements and body fat percentage.

Does weight lifting make you gain weight?

Strength training results in muscle gain, injury prevention and more power in your stride. It should be part of every runner’s training plan and it’s a required part of everyone I coach!

But if you’re still focused on the scale, let’s break this down a bit more.

Yes, strength training could cause weight gain if you are actually building muscle or if you are overeating.

  • If you replace 10lbs of fat with 5lbs of muscle then you lost weight and fat
  • If you lose 5lbs of muscle from strict dieting and don’t build muscle, the scale has gone down but your body fat has gone up and your metabolism has dropped
  • If you lose 5lbs of fat, gain 10lbs of muscle then the scale has gone up, but your body fat has dropped and the overall appearance is a much leaner figure

Looking for more information on working out and gaining weight?

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Does Muscle Weigh More than Fat? is written by amanda for

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