Obese, Overweight, Normal – Exactly What Do They Mean?

You’ve heard it before. Being overweight is a risk factor for diabetes, stroke, heart disease, arthritis and certain cancers. It lowers your life-expectancy. Or – is it being obese that’s a risk factor? Just what is the difference between obesity and overweight? What is a “normal” weight?

Being overweight means just that. The individual weighs more than is recommended for his/her height. But the excess weight may be from muscle, bone, water or fat.

Being obese means having excess weight that comes from fat, not from muscle, bone or water. It means that a person has taken in more calories than he/she was able to use up. There is an imbalance. This caloric imbalance has gone on for some time.

So, what is a “normal” weight, a weight that is healthy? If being overweight can be cause by large muscles, large bones or excessive retention of water, how should someone’s weight status be determined? First of all, excessive and prolonged water retention is a symptom of disease and needs to be evaluated by a healthcare professional. If the excess weight is not from water retention, there are two methods you can use at home.

One way of determining if you are at a healthy weight is to calculate your body mass index (BMI). This is not a fool proof method (muscle does weigh more than fat) nor should it be used in isolation. However, it’s one measure which gives an indication of weight and health risk status. To calculate your BMI, square your height in inches, e.g., 5 ft 4 inches equals 64 inches. Sixty-four squared is 4096. Divide this number into your weight in pounds, e.g., 160 pounds divided by 4096 equals 0.039. Multiply this number by 703 and the result is 27.4. Now, for the interpretation:

BMI Weight Status

Below 18.5 Underweight

18.5 – 24.9 Normal

25.0 – 29.9 Overweight

30.0 and above Obese

For a short-cut to finding out your BMI, you can use the Body Mass Index Table available at http://www.nhlbi.nih.gov/guidelines/obesity/bmi_tbl.htm.

Another measure to use is waist circumference. In general, men are considered overweight if their waist measurement is greater than 40 inches. For women in general, the measurement is 35 inches. Excess fat around the middle of the body seems to pose more of a health risk than the same amount of fat elsewhere. When combined with a BMI of 25 or more, the health risk is even greater. Measuring waist circumference is also a way of eliminating excess weight that may be due to large bones or muscles.

So – we’re back to “normal”. If you have a BMI between 18.5 and 25 and a waist circumference of 35 (women)/40 (men) or less, you can be pretty sure that you are at a normal AND healthy weight.

Health – it’s about prevention.


Mary Lou Bernardo, PhD, MSN


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