Life expectancy is hardly affected by weight in the normal – overweight – obese range. BMI 30-34.9 = obese.

Lets imagine you are a 5’10” man and you weigh 140 lbs. In that case, you have a BMI of 20, and you probably think you’re pretty healthy, or perhaps you think you’re a bit overweight. Our institutes of health will say that you are an “average-wight” or “normal-weight” American, and then claim that the average-weight American is overweight. What they don’t tell you, is that low weight, and so-called average weight people in the US live shorter lives. Other things being equal, the morbidity (chance of death) for a thin American, BMI 18.5 is nearly triple that of someone who’s obese, BMI 32. The morbidity of the normal-weight American is better, but is still nearly double that of the obese fellow whose BMI is 32.

Our NIH has created a crisis of overweight Americans, that is not based on health. They work hard to solve this obesity crisis by telling people to jog to work, and by creating ever-more complicated food pyramids. Those who listen live shorter lives. A prime example is Jim Fixx, author of several running books including “The complete Book of Running.” He was 52 when he died of a heart attack while running. Similar to this is the diet-expert, Adelle Davis, author of “Let’s eat right to keep fit”. She died at 70 of cancer — somewhat younger than the average American woman. She attributed her cancer to having eaten junk food as a youth. I would attribute it to being thin. Not only do thin people live shorter lives, but their chances of recovering from cancer, or living with it, seem to improve if you start with some fat.

The same patter exists where age-related dementia is concerned. If you divide the population into quartiles of weight, the heaviest has the least likelihood of dementia, the second heaviest has the second-least, the third has the third-least, and the lightest Americans have the highest likelihood of dementia. Here are two studies to that effect, “Association between late-life body mass index and dementia”, The Kame Project, Neurology. 2009 May 19; 72(20): 1741–1746. And “BMI and risk of dementia in two million people over two decades: a retrospective cohort study” The Lancet, Volume 3, No. 6, p431–436, June 2015.

Morbidity and weight, uncorrected data, and corrected by removing the demented. The likelihood of dementia decreases with weight.

Now you may think that there is a confounding, cause and effect here: that crazy old people don’t live as long. You’d be right there, crazy people don’t live as long. Still, if you correct the BMI-mortality data to remove those with dementia, you still find that in terms of life-span, for men and women, it pays to be overweight or obese but not morbidly so. The study concludes as follows: “Weight loss was related to a higher mortality risk (HR = 1.5; 95% CI: 1.2,1.9) but this association was attenuated when persons with short follow-up or persons with dementia were excluded.” As advice to those who are planning a weight loss program, you might go crazy and reduce your life-span a lot, but if you don’t go crazy, you’re only reducing your life-span a little.

In terms of health food, I’ve noticed that many non-health foods, like alcohol and chocolate are associated with longevity and mental health. And while low-impact exercise helps increase life-span, that exercise is only minimally associated with weight loss. Mostly weight loss involves changing the amount you eat and changing your clothes choices to maximize radiant heat loss.

Dr. Robert E. Buxbaum, October 26, 2017. A joke: Last week I was mugged by a vegan. You may ask how I know it was a vegan. He told be before running off with my wallet.