We treat height/weight tables as if they are truth. We believe they are based on sound science. But, in fact, most height/weight tables are based on questionable research which began in the early 1900's.
Let's take a look. In the early 1900's, the Metropolitan Life Insurance Company wanted to make more money, so set out to find more risk factors associated with premature mortality. The plan was to charge higher premiums, or refuse to insure applicants with certain risk factors. They decided the risk factor would be weight, partly because it is easy and cost effective to measure. They did some research resulting in height/weight tables which have been the foundation for weight recommendations for decades. Few people in the U.S. have escaped having their own weight compared to them.
But there are many, many problems with the research in this study, including, but not limited to the facts that life insurance policy holders:
- Are not representative of Americans.
- Weigh five to ten pounds less than the average American.
- Have mortality rates up to 40% lower than the general population.
But it gets worse. There were additional methodological flaws in the studies:
- Mortality was defined as the cashing in of a policy, not the death of a person. (In other words, one person could hold 5 policies, when they were cashed in, it was recorded as 5 deaths.)
- All persons were included in the 1959 study whether the policy was purchased in 1935 or in 1953...what sounds like a 20-year study has an average follow-up of 7.8 years.
- The policyholders were never questioned about eating or exercise habits (which impact mortality regardless of weight).
- Weights and heights were self-reported in 10 to 20 percent of cases.
- Weights were recorded only once, so we don't know if policyholders lost or gained any weight during the study--which they probably did (one study in the 80s found that ½ of adult Americans gained or lost up to 15% of their body weight over 10 years!).
Okay, these innumerable flaws are interesting. But it gets even worse. Bear with me here.
The first weight table was actually based on the average weights of policyholders sampled. So, the average weight of a 5'4" woman who was 20 to 29 years old was 126 pounds. For a woman who was 60 to 69, 144 pounds. This average weight was what was recommended. Overweight was defined as anything over the average weight of the general population (divided by sex and age). However, studies showed that mortality did not increase appreciably until a person was at least 20 percent over average weight (which was 151 pounds for the 20‑29 year old woman, and 172 pounds for the 60-69 year old woman).
The result? Height/weight tables at that time recommended that we would have to weigh 20 to 30% above average before experiencing any appreciable increase in mortality. This would be between 151 and 164 pounds for the 20 to 29 year old woman. And only those 20% above the average weight were required to pay higher premiums.
But all things change, and not necessarily in response to sound science. Height/weight tables tend to change more in response to social trends than science. In 1912, this 5'4" woman was an average of 144 pounds, and at no risk of increased mortality until somewhere around 151 to 187 pounds. But, in 1942, this same woman was considered obese and determined to be risk of multiple health problems and early death.
The following chart shows how weight recommendations changed. (There is a direct correlation between the changes in recommendations for women and social issues.) It shows the changing weight requirements from the Metropolitan Life Height/Weight Tables for a woman who was 5'4":
It is noteworthy that when the weight recommendations were LOWERED, they were lowered more for women than for men. When weight recommendations INCREASED, they increased more for men than for women. The result was that men could be quite a big larger and still be considered healthy, while women needed to be quite a bit thinner to be considered healthy. This is the OPPOSITE of research conclusions, which show that women typically can carry more weight than men and still be healthy.
But the life insurance industry's conclusions have not only been accepted as truth, most people interpret them to mean that any degree of overweight will increase mortality. Glenn Gaesser, author of Big Fat Lies, exposes how there has been little critical evaluation of the data, and as a result, the belief that weight is a primary determinant of health problems has been influencing scientific investigations ever since. While some types of obesity present health risks for some individuals, the level of fatness that poses health risks cannot be determined from a height/weight table or percent of body fat testing.
One day we will realize that for most Americans, and indeed most people in this world, weight need not be an issue in regards to health.