What's a Normal Bodyweight?

Tuesday, September 26, 2006 - 2:38pm

By John Messmer, MD

Well-built, pleasantly plump, more to love—we have lots of euphemisms for being overweight. It’s not surprising because most of us are overweight, but is it really a problem?

Let’s take a look at what “being overweight” actually means. Unfortunately, popular press and movies have distorted our ideas of normal bodies, emphasizing body weights not realistically achievable by the average American, and in some cases dangerously low. Compounding the problem, photos of models are often edited to make them look thinner than they are, setting the standard for thinness even lower. When we realize we cannot achieve the level of thinness portrayed in the media, it’s easy to just give up.

Body Mass Index (BMI): defining "normal"

Normal weight is measured by the body mass index or BMI. The formula to measure BMI is body weight in kg divided by the square of the height in meters. Normal BMI is between 20 and 25. Check your BMI here.

Above 25 is considered overweight and above 30 is obese. That’s not just name-calling; when you’re obese your risk of serious health conditions such as diabetes, high cholesterol and heart disease, increases significantly. Being overweight also contributes to gall bladder disease, stroke, some forms of cancer, breathing difficulties, arthritis, menstrual irregularities, and hair and skin diseases.

Another measure of healthy weight

There is a rule of thumb for body weight that may be used instead of BMI. For women, ideal weight is 100 pounds for the first five feet of body weight, with approximately 4-7 pounds for every inch over five feet. This results in a BMI between 20 and 23. For men, normal weight is 105 pounds for the first five feet and 5-7 pounds for every inch over five feet, for a BMI between 22 and 25. These are the ideal weights. A man who is 5’ 10” is overweight when he weighs more than 174 pounds. A woman who is 5’ 7” is overweight when she exceeds 159 pounds.

Obesity is a dangerous health concern

In nine out of 10 cases, type 2 diabetes is caused by being overweight. This is because body fat secretes a chemical called adiponectin which helps sugar move from the blood into the muscles where it is burned. When there is too much fat, less adiponectin is produced reducing the body’s ability to move sugar from the blood into the muscles so blood sugar levels go up. More than just raising blood sugar, when adiponectin levels are low, arteries start to clog with cholesterol. Being overweight can also raise cholesterol levels, making the arteries more diseased. Blood pressure may be higher in overweight individuals, adding one more insult to the circulatory system.

A low BMI is skinny and not necessarily healthy

It is not necessary to be skinny to be healthy. Unless recommended by a physician, seeking a BMI below 23 is done for appearance, not for health. The BMI of some of the top models may be less than 18, a range that borders on unhealthy and may be a sign of an eating disorder. The fashion industry is joined by gymnasts, runners and other athletes and dancers in seeking weights too low for good health.

If we set a standard for ourselves that is unrealistically low, we may be frustrated in achieving and maintaining it. It might feel like entirely too much work, causing us to give up seeking even a normal weight. The best plan is to calculate a reasonable weight and plan a balanced diet that allows us to stay at that weight.