What is the healthiest BMI?

Welcome!. I originally made this review in 2002. However, it still holds value and was updated in 2014.

What? You have proof that growing heavier with age is healthy.

body mass index associated obesity mortality

Comments and Key points from this article on healthiest BMI

The above article on Body Mass Index (BMI) has a key point, and here it is:-

“The estimated nadir of the BMI curve was at 27.3 kg/m².”

But what does this actually mean? Well, the lowest mortality rate (death rate) occurs at a Body Mass Index of 27.3. Thus, 27.3 is the healthiest BMI when assessing by mortality rates.

What?

They (the CDC) call a BMI of 27.3 overweight, but it has THE LOWEST MORTALITY rates.

Is that true?

Increase in Mortality Rates and LOW Body Mass Index

Yes, it is true. Indeed, a closer inspection reveals more. Other studies also show that an elevated mortality rate is associated with a low BMI^1,2. and lowest mortality around the median BMI levels.

What is that, median BMI levels?

Median, means like the average BMI, like the center of the bell-shaped curve.

So what is happening naturally with people’s weights, is healthiest in the middle range?

‘Fat’ and ‘Fat-Free Mass’ Indicators

The article above shows a graphic like the one below, but I have relabelled fat mass indicator as “fat” and fat-free mass indicator as “muscle” ( to make the graph easier to understand).

The graph shows that health hazard ( risk of death ) increases as fat increases.

Another thing to notice, about that dotted line for fat. It’s rather flat-sloped, so fat doesn’t actually have much effect on the Hazard ratio numbers.

But fat DOES affect likelihood to have a lot of sex, right?

That’s a different topic, but you’re kind of wrong about that too.

Notice the body mass index has “U-shaped” curve that has its lowest risk at 27.3 kg/m².

As you can see, increasing your muscle mass (by fitness, exercise, weight-lifting, etc) is the most effective way to become healthier. Dieting to reduce fat isn’t as effective.

References

Kalmijn S, Curb JD, Rodriguez BL, Yano K, Abbott RD. The association of body weight and anthropometry with mortality in elderly men: the Honolulu Heart Program. Int J Obes Relat Metab Disord 1999 Apr;23(4):395-402
Heitmann BL, Erikson H, Ellsinger BM, Mikkelsen KL, Larsson B. Mortality associated with body fat, fat-free mass and body mass index among 60-year-old swedish men-a 22-year follow-up. The study of men born in 1913. Int J Obes Relat Metab Disord 2000 Jan;24(1):33-7

2014 update

In December 2014, while applying new styling onto these webpages, I found a more recent article on this topic, and here it is. It’s for people age 51 or older.

This New article about Obesity and Mortality risk, using body mass index trajectories

There’s a very interesting quote in that new abstract.

“People in the overweight stable trajectory had the highest survival rate“

Reference: Zheng H, Tumin D, Qian Z, Obesity and mortality risk: new findings from body mass index trajectories. Am J Epidemiol, 2013; 178:1591-9

Here are the charts from the study. First is showing the 2 healthiest categories, called “overweight stable” and “overweight obesity”, colors red and blue.

Please notice the green BMI numbers. They are all above 25, and healthy.

Next shown is the actual survival curves. Notice red and blue lines have highest survival.

Another cool quote from the article:

“People who were overweight at 51 years of age and remained overweight through age 77 years had the lowest mortality risk.”

Baseline (at age 51) Normal weight, overweight and class 1 obesity (BMI 18.5 through 34.9) were not associated with significant increases in mortality risk.”

But don’t think that weight gain is harmless. It isn’t. IF you continue to have weight gain after age 51, in a faster upward trajectory than average, then it does lower future survival.

If you are over age 51 and your BMI is between 25 to 30, that is the healthiest.

Another fun fact. The average man at age 51 weighs 184 pounds and is 70 inches tall and has a BMI of 26.6. The average woman at age 51 weighs 155 pounds and is 64 inches tall with a BMI of 26.6. So Both men and women with an average BMI of 26.6 are extremely close to the healthiest BMI of 27.3 ? Is that a coincidence? Maybe it’s Nature. Maybe what happens to our weight as we age, is inherited genes at work, and our population’s weight average is showing biologic wisdom.

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