Muscle Weighs More Than Fat – A Common Weight Loss Myth

I’m sure you’ve heard it, that explanation for the phenomenon when you’ve been exercising and dieting and your weight stays the same, “Muscle weighs more than fat. Even though you aren’t losing weight you’re still losing fat.” I’m sorry to say that this is one of the most regularly shared weight loss myths between dieters.

When I began exercising regularly as part of my diet regime I noticed there would be times when my weight would stand still. I recall a span of five days when I worked out like mad at the gym and stuck to my diet and was aghast every morning when I weighed myself and my weight was exactly the same. I’m talking exactly, not up or down, just the same. I began thinking that perhaps this was my body’s way of getting revenge from taking away all those delicious calories and making it go to the gym.

The majority of my workout is cardio, but I do strength training for 30 minutes 3 times a week. I can’t say exactly how much muscle I gain from this program, but for hypothetical reasons I will estimate that I gain an average of 0.5 lb of muscle a week. Now, it is true that muscle is denser than fat (see below for fat vs. muscle example), but weight is weight. So if I gained half a pound of muscle, then did I lose only a half a pound of fat, or are there other factors at play?

After reading lots of articles about muscle building and general muscle physiology I can offer these three factors as explanation for my stubborn weight loss – water retention, glycogen storage and muscle gain.

Water Retention – there are a number of reasons you will gain water weight; you haven’t been drinking enough water so your body stores more of it; excess salt in your diet; monthly hormonal changes; water stored with glycogen in muscles.

Glycogen Storage – glycogen is carbohydrates kept for future use that is stored in the liver and muscle tissue along with a large amount of water that is needed for its metabolism and can account for weight gain following carbohydrate intake.

Muscle Gain – as I hypothesized above, I expect my average muscle gain to be about half a pound every week, which I expect contributes relatively very little to explaining why sometimes your weight plateaus.

As you can see, gaining muscle has very little to do with stubborn weight loss. If you are sticking to your diet, are exercising regularly (making sure to mix up your exercise routines) and your weight is still at a stale mate, then make sure to drink plenty of water, avoid salt in your diet and reduce the amount of carbohydrates you are eating.

Density of Muscle versus Fat

Density is simply the ratio of mass to volume. The density of fat is about 0.9g/ml whereas the density of muscle is about 1.06g/ml. (For conceptual purposes, it is helpful to convert 1 ml = 0.06 cubic inches.) If you gain one pound of muscle and lose one pound of fat your weight will stay the same but you will lose 4.6 cubic inches of body volume (e.g. inches around your waist) as demonstrated using these calculations:

454g (1 lb) muscle x 0.06 cubic inches/1.06g = 25.7 cubic inches

454g (1 lb) fat x 0.06 cubic inches/0.9 g = 30.3 cubic inches

25.7 cubic inches gained – 30.3 cubic inches lost = 4.6 cubic inches lost

This example demonstrates that if you gain the same weight of muscle that you lose in fat, hypothetically your weight will stay the same, but you will still lose inches from your waistline.