Is Being Overweight a Health Risk?

It depends on the question - a health risk for what? People who are overweight, defined by the U.S. government and the World Health Organization as a Body Mass Index (BMI) of between 25 and 30, apparently do have a slightly increased risk for certain diseases such as diabetes, coronary artery disease and hypertension. But for other parameters, such as risk of death, the evidence is not that clear-cut (See “Is ‘Overweight’ Overstated?”, pp. 346-347, Human Biology 5th ed.). In fact, a recent study of over 11,000 Canadian adults reveals that as a group, people who are defined as overweight have a slightly lower risk of death than the normal-weight group, though not by much.

Taking this new mortality data into account and reviewing the graph on p. 346 of Human Biology, one wonders whether the range of “normal” weight shouldn’t be shifted about 3 BMI to the right. A word of caution, however; the shape of the weight-vs.-risk curve is likely to be different for every disease, age group, etc. It’s probably going to be impossible to come up with a perfect functional definition of overweight, no matter how much we’d like to.