Is there a unisex chart for optimal weight based on height?
We seem to have become inured to the mortal threat of obesity. If you go back in the medical literature almost a quarter of a century ago when obesity wasn’t run-of-the-mill, the descriptions are much grimmer: “Obesity is always tragic, and its hazards are terrifying.” Not just obesity, though. Of the four million deaths attributed to excess body fat each year, nearly 40 percent of the victims are overweight, not obese. According to two famous Harvard studies, weight gain of as little as 11 pounds (5 kg) from early adulthood through middle age increases the risk of major chronic diseases, such as diabetes, cardiovascular disease, and cancer. The flip side, though, is that even modest weight loss can have major health benefits.
What is the optimal body mass index, commonly known as BMI? The largest studies in the United States and around the world found that having a BMI of 20 to 25 is associated with the longest lifespan. Put all the best available studies with the longest follow-up together, and that can be narrowed down even further to a BMI of 20 to 22. That would be about 124 to 136 pounds (56 to 62 kg) for someone who’s five-foot-six (168 cm), as you can see below and at 1:22 in my video What’s the Ideal BMI?.
Even within a “normal” BMI range, the risk of developing chronic diseases, such as type 2 diabetes, heart disease, and several types of cancer, starts to rise towards the upper end—starting as low as a BMI of 21. BMIs of 18.5 and 24.5 are both considered to be within the “normal” range, but a BMI of 24.5 may be associated with twice the risk of heart disease compared to a BMI of 18.5.
Below and at 2:05 in my video is a graph of diabetes risk and BMI among women. There is a fivefold difference in diabetes rates within the so-called ideal range with a BMI under 25.
Just as there are gradations of risk within a normal BMI range, there is a spectrum within obesity. Class III obesity (BMI over 40) can be associated with the loss of a decade or more of life. At a BMI above 45, for example, a person standing at 5’6″ (168 cm) and weighing 280 pounds (127 kg), life expectancy may shrink to that of a cigarette smoker.
However, “skeptics have argued that the consequences of rising obesity levels have either been greatly exaggerated or are unclear.” A “motley crew,” “obesity skeptics are made up of a kaleidoscope of interest groups…includ[ing] feminists, queer theorists, libertarians, far right-wing conspiracy types and new ageists.” It “has also been popular on far right-wing, pro-gun, pro-America websites where the idea that obesity alarmists are nanny-state communists who simply want to stop us from having fun plays well….”
Unlike activists who organized to raise consciousness and stamp out the AIDS epidemic, for example, some in the size acceptance movement appear to have the opposite goal and “have called for less public awareness and intervention regarding obesity,” less treatment of the problem. I’m all for fighting size stigma and discrimination—I have a whole section on weight stigma in my book How Not to Diet—but the adverse health consequences of obesity are an established scientific fact.
Can’t you be fat but fit? In a study of more than 600 centenarians, only about 1 percent of the women and not a single one of the men were obese. There does appear to be a rare subgroup of individuals who are obese and do not suffer the typical metabolic costs, such as high blood pressure and cholesterol. This raises the possibility that there may be such a thing as “benign obesity” or “metabolically healthy obesity.” It may just be a matter of time, though, before the risk factors develop. Even if they don’t, though, when followed long enough, even “metabolically healthy obese adults” are at increased risk of diabetes, as well as increased risk of fatty liver disease. They are also at greater risk of cardiovascular events, such as heart attacks, and/or premature death, as shown below and at 4:20.
Bottom line? There is “strong evidence that ‘healthy obesity’ is a myth.”
Many “fat activists” try to downplay the risks of obesity, even as they may be among “the greatest victims” of the epidemic. “Leading fat acceptance activist Lynn McAfee, who is director of medical advocacy for the Council on Size and Weight Discrimination and takes part in obesity conferences and government panels on obesity,” is quoted as saying, “‘I’m not actually particularly that interested in [health] and God I hate science….”
If you missed the previous blog posts in this series on obesity, see related posts below.
The final video in this series is What’s the Ideal Waist Size?.