Listen to gym conversations enough and you are sure to hear someone say, I weigh more now than when I started to workout a month ago but my trainer says it’s because muscle weighs more than fat. 

Well, which weighs more, fat or muscle?  The answer to that is simple.  Five pounds of muscle weighs the same as five pounds of fat, they each weigh five pounds.  There is a difference in the appearance of five pounds of fat versus five pounds of muscle however.  Fat occupies more space.  It is a bulkier, jelly like substance and muscle is a compact tissue. 

Muscle density is 1.06 g/ml and fat density is (about) 0.9 g/ml.  One liter of muscle would than weigh 1.06 kg and one liter of fat would than weigh 0.9 kg.  Stated in another way, muscle is 18% more dense than fat.

Interestingly, muscle cells are denser than fat cells, which means there are more cells in a smaller area than there are in fat cells.  Fat cells contain mainly oil where muscle cells contain mainly protein.  As an example, if you were to stack up 10 pounds of pennies and 10 pounds of feathers, they would still weigh ten pounds but the stack of feathers would far out size the stack of pennies.  Make sense? 

The same applies to our bodies.  A woman weighing 130 pounds and having 35% body fat will be larger in size than a woman weighing 130 pounds and having 15% body fat. The lower body fat is being compensated for by higher muscle mass. 

Let’s take a closer look at each type of cell to fully understand what it is and how it reacts to stimulus such as food and exercise. 

Fat is the result of eating too much of any type of food, be that protein, carbohydrates or fats.  When you expend fewer calories than you ingest, you gain fat.  The fat cells in your body can do one of three things; they can grow and even divide, they can remain unchanged or they can shrink.  Of those three options, fat cell variation depends on how much you eat versus how much you exercise.  There is much research being done on fat cells and how they divide and replicate and so on. There are some reports that challenge the old belief that we create all our fat cells as infants and young children and that we as adults have all the fat cells that we ever will.  

Muscle cells on the other hand are very different.  Muscle cells are composed of muscle fibers which cannot divide or increase in number, only grow in size and strength or conversely atrophy and shrink.

In conclusion, what muscle and fat cells weigh is not as important as the composition of each in your body.  Increase muscle mass, your weight goes up; decrease fat stores your weight goes down.  The bottom line is adding muscle to your body is good for you if you are trying to look slimmer.  As an added benefit, increased muscle mass means you have an increased rate of metabolism so you are burning more calories even at rest.

By Christina Leon, Staff Writer