Photo Credit: Bambu Productions
Did you know that you could have high lean body mass and low body fat and still be overweight? It's true. You can't simply just look at someone and deem that they are overweight or at risk of disease like most may think. There are several ways to determine someone's "size."
So, how can we size ourselves up? It’s not just how you look. The methods described below are based on large-scale scientific studies. But, you can’t always translate population statistics for your personal evaluation. It makes sense to use at least two of these tools, while also taking your family history into consideration.
Are your familiar with these methods? How do you size yourself up?
- Body mass index
- Percent body fat
- Lean body mass (muscle)
- Waist circumference
Body Mass Index (BMI): This is the best way to start sizing yourself up. BMI takes into account your height and weight, for a single number representing weight categories. It’s the same for men and women. You can find out your BMI by consulting a BMI chart. You can also calculate this with pen and paper:
- Multiply your weight in pounds by 703.
- Divide this number by your height in inches.
- Divide this again by your height in inches.
A BMI between 18.5 to 23.9 is healthy range.
Bottom line: This is an important starting point. Pick a part of your range that is manageable for you to maintain. No matter where you are on the BMI chart, it’s important to at least not gain—and avoid weight gain creeping up on you with age.
Waist circumference: All you need is a tape measure going around your waist at "belly button" level. A healthy waistline is one that is half your height (in inches), or less. If it’s higher, no matter what your BMI, that indicates extra abdominal fat (also known as "belly fat"). Extra abdominal fat is a known health risk for metabolic syndrome and diabetes.
Bottom line: It’s not just your BMI, but also your waist that matters—a reflection of where the fat is. You don’t have to look especially heavy, but if your waist is larger, you’re at a greater risk for diabetes and metabolic syndrome (high blood pressure, high insulin).
Lean Body Mass (LBM): Muscle, bone, and body fluids make up the term "lean body mass". Much of this is represented by your muscle mass. Muscle is more dense than fat, and weighs more, so the scale can be higher with higher muscle mass. Higher muscle mass also reflects a lower body fat percentage. Importantly, muscle has twice the metabolic activity of fat. This is important for aging to keep metabolism up and fight the natural decline in metabolism with age. A person with a higher lean body mass and low body fat could have a BMI that is "overweight", but without health risk. They are in great metabolic shape because of their muscle mass. No need to measure more than a couple of times a year (Note: Muscle and fat measures are done at the same time—see below).
Bottom line: Muscle weighs more than fat. Raising your muscle mass is a goal for life—to offset the decline in metabolism that occurs every decade from age 30 on. That’s why people wonder why it’s harder to lose weight at 45 than 25. So, even if you have a BMI that is "overweight", if you have a high LBM (reflected as a lower body fat as well), it’s your muscle that provides the extra “weight”—in this case, a very good thing.
Percent Body Fat: Body fat is a key measure for overall health. It’s everything that is not lean body mass. Body fat percentage helps predict future health risk (for diabetes, metabolic syndrome, and others) and also metabolic efficiency. High body fat reflects more fat cushioning your organs, which is a problem. Also, for women, in particular, the slowing of metabolic rate by five percent a decade promotes weight gain. Higher body fat means slower metabolism, which only makes this worse. Many people can have a "normal" BMI—and be "overfat" or also “underfat”—both which can be a problem for normal hormonal function. A fit woman has a body fat of around 21 to 24 percent; a fit man has a body fat of around 14 to 17 percent. While a low body fat percentage is a real health promoter, there is a need for some body fat for good health. Women shouldn't drop below 12 percent and men shouldn't drop below four percent.
While home scales can give you an approximate body fat percent, there’s a lot of variability, and these are best to measure the changes you have over time, either up or down. The best information is obtained at a gym, or medical setting by experienced people using professional equipment.
Bottom line: Body fat is important to pay attention to, to keep your metabolism revved up throughout life. Too much or too little fat is a problem—independent of weight.