Time and time again we've heard that muscle is the most metabolically active tissue, which is why we should work to gain more of it to help increase our metabolism. If you really want to try and increase your metabolism, you first have to know what increases your metabolic rate.

Metabolic rate is determined by the amount of fat-free mass (FFM) in your body. But what exactly makes up fat-free mass in your body? Three main components: Internal organs, muscle, and bone. One pound of bone increases your metabolic rate by just one calorie. Now, before you go praying for heavier bones, keep in mind this is not a significant enough amount, so you don’t need to worry about it. For all of you “big boned” individuals out there, you can just thank your mom and dad for naturally increasing your metabolic rate all that much more.

As I mentioned in my MythBuster blog, "Building Muscle Significantly Increases Metabolism," one pound of muscle increases metabolism by just 6 calories per day. So, are you ready for the most metabolically active tissue in your body? Drum roll, please: It's your internal organs! One pound of internal organs can actually increase your metabolic rate by 24.4 calories per day. There you have it everyone, your internal organs like your heart, liver, pancreas, spleen, and kidneys are your most metabolically active tissues.

This is actually why obese individuals have a higher metabolic rate than thinner, leaner individuals (even though they may feel otherwise). The larger an individual is in body mass, the larger their internal organs will grow to help supply blood, remove toxins and carry on metabolic processes in general.

The larger the person, the more it takes to keep them living. I would by no means recommend that anyone get larger to increase one's metabolic rate, however. The heavier you are, the more stressful and taxing it is on your internal organs, resulting in a decreased shelf life of the only set of organs you have.

There you have it, another myth dispelled.