Some lines on reading a Weight Watchers study.

So, the other night, I started reading this 2008 study, which looked at how well Weight Watchers Lifetime Members do at maintaining their weight loss for up to five years.

The first part of the paper, as usual, describes the set-up of the study, and the demographic details of the people who participated. This is a part of studies I always like a lot, because, if it’s an intervention study with both a treatment and control group, I like to see the wondrous effects of good randomization on the average profile of both groups. Because I am a nerd.

In this case, it’s not a treatment group vs. control group comparison, but a profile of your average Weight Watchers Lifetime Member, based on a nationwide sample. And here’s what we get:

(The red markings are mine.)

So, based on this sample, the average Weight Watchers Lifetime Member is a married female, 45 years or older, who started WW weighing 165 lbs. with a BMI of 27.6 (in the overweight range.) She has an income of at least $50,000 a year.

You probably already know that people with BMIs in the overweight range have the lowest relative risk of death:

Overweight was associated with a slight reduction in mortality … relative to the normal weight category.

…and that women tend to live longer than men:

Today, males have greater mortality than females throughout the world. The very few exceptions are in southern Asia where it has been demonstrated that females receive less food and health care than males. With relatively equal treatment, males universally experience greater mortality than females.

…and that people with more money tend to have better health:

The relationship between socioeconomic status and health outcomes is one of the most persistent themes in the epidemiological literature. The strong and growing evidence that higher social and economic status … are associated with better health has led most researchers to conclude that these factors are fundamental determinants of health.

…and that the average income of Weight Watchers Lifetime Members ($50,000 and up) is roughly at or above the median household income for the United States in 2008:

Median income (dollars) 52,175

…and that a higher BMI actually has a protective effect on mortality as people get older.

Which forces me to conclude that the people who become “successful” Lifetime Members of Weight Watchers? Not only are they not very fat to begin with, but also have few of the risk factors that contribute, systemically, to poor health and premature death.

So, for the purposes of this study, at least, we can dispense with the notion that people join Weight Watchers not to diet (since the word “diet” is now outrĂ© in diet advertising) — heavens no, but for the good of their health, darling.

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