Unpacking Body Composition Lingo

A Guide to Basic Body Composition Terminology

Percent Body Fat (Body Fat Percentage)

If you walk away with just one new term under your belt, walk away with this one: Percent Body Fat. It’s a reflection of how much of your weight is made up of body fat and is calculated by dividing the weight of your body fat mass by your total weight. It is a deceptively simple metric but has an awesome number of highly relevant uses.

What You Can Learn From It:

Percent Body Fat is always expressed, obviously, as a percentage. This percentage can then be applied to set percent body fat ranges. While there are no official, set-in-stone ranges like there are for BMI, you’ll find that the healthy ranges tend to hover around 10-20% percent body fat for men and 18-28% for women. Organizations offering set ranges include ACSM and ACE; you can view theirs as well.

Skeletal Muscle Mass

When people talk about their muscles, they’re more than likely talking about Skeletal Muscle Mass. Skeletal muscle is one of the three major muscle types (the others being cardiac and smooth) and is the type that governs all the movements you can consciously control: everything from typing out a text to deadlifting a 300-pound barbell. It’s also the muscle group you’re growing when you exercise.

Value To You: Increased Skeletal Muscle Mass typically translates into increased strength. If you’re trying to build up your body and grow in size, this is the value you’d want to track and see increases in over time.

However, muscle isn’t just for strength. Muscle is composed of primarily protein and can act as a “protein bank.” Why would you want a protein bank? When your body gets put under severe stress – such as in a traumatic injury – the recovery process is triggered and requires additional protein, up to four times the amount in some cases. When it’s not able to get that amount of protein from your diet, your body will start getting what it needs from the protein bank – aka your muscles.

Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate, or BMR, is the number of calories that your body requires to maintain its Lean Body Mass. It’s a huge component of your overall metabolism. Someone with more Lean Body Mass will have a higher BMR than someone with less BMR. It’s the reason why a 250-pound NFL linebacker needs to eat more than a 150-pound sedentary adult – the linebacker has far more Lean Body Mass.

Value To You: Outside of your Percent Body Fat, if you learn a second thing today, learn the value of your Basal Metabolic Rate. Used properly, your BMR can help you make a nutritional plan designed for either fat loss or muscle gain by helping you understand how much energy (read: calories from food) your body needs.

By multiplying your BMR with an activity factor, you can get a general estimate of your Total Daily Energy Expenditure (TDEE). Using your TDEE as a baseline, you can start to craft nutritional plans for yourself based on what you want to do with your body composition.

Want to lose fat? Create a caloric deficit by decreasing energy in (food) and increasing energy out (exercise). Looking to increase muscle? Eat more than your TDEE requires and use that extra energy to hit the weight room and build new muscle.

Body Water

You may have heard somewhere along the line that “humans are mostly water.” Generally speaking, that’s true. Your Body Water includes all the water in your body, everything from the water in your blood, to the water in your organs, to the water inside your bones.

Your body water is usually subdivided into two types: intracellular and extracellular. Intracellular (inside the cells) includes the water in your organs, muscles, and such, composing 2/3 of your total body water. The remaining 1/3 is the extracellular (outside the cells) water and includes the water in your blood.

Value To You: Hopefully, you never have to worry about body water. If you’re generally healthy, your body maintains a healthy balance of intracellular to extracellular water (at a ratio of about 3:2). It’s when this balance becomes broken that monitoring your body water becomes very important.

People who have severe health problems, particularly those with kidney failure, will be unable to rid their bodies of extracellular water. This causes buildup of body water requiring removal through procedures such.

Visceral Fat

There are two major categories of body fat. Subcutaneous fat is the fat under your skin, and it’s the type of fat that you can see. The second type of fat is called visceral fat. This type of fat collects inside your abdomen and wraps around your internal organs.

Why It’s Worth Knowing About: Just because you can’t see it doesn’t mean it’s not there. In the case of visceral fat, if it is there, you’ll definitely want to know about it. That’s because visceral fat is not just extra pounds – it’s an active organ that secretes harmful hormones in your body that triggers perpetual inflammation. The more visceral fat you have, the greater risk of inflammation. Inflammation over time can put undue stress on the heart, leading to cardiovascular problems later on.

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