What is your risk of death based on your BMI?

What is your risk of death based on your BMI?

Watch: https://youtu.be/H6_3sFxO-bw

Title: Body-mass index and all-cause mortality: individual participant- data meta-analysis of 239 prospective studies in four continents

Author: Global BMI Mortality Collaboration

Journal: Lancet

Objective: Meta-analysis to assess the all-cause mortality as it related to body mass index.


Body mass index is a way to quantify obesity based on height and weight. If you haven’t watched my video on BMI, check it out to get a more thorough description.

BMI Explained: https://youtu.be/1PyrXtYON1k

Essentially, you use your height and weight to calculate a number that helps predict your health.

  • <20 is underweight (some say < 18.5)
  • 20-24.9 is normal
  • 25-29.9 is overweight
  • >30 is obese
    • Class I: 30.0-34.9
    • Class II: 35.0-39.9
    • Class III: >40.

Being overweight or obese based on BMI is known to increase your risk of

  • Coronary heart disease
  • Type 2 diabetes
  • Cancers (endometrial, breast, and colon)
  • Hypertension (high blood pressure)
  • Dyslipidemia (for example, high total cholesterol or high levels of triglycerides)
  • Stroke
  • Liver and Gallbladder disease
  • Sleep apnea and respiratory problems
  • Osteoarthritis (a degeneration of cartilage and its underlying bone within a joint)
  • Gynecological problems (abnormal menses, infertility)

According to the WHO, more than 1.3 billion people are overweight or obese globally, so it’s easy to see how this is becoming a global public health crisis.

The authors of this study wanted to complete a meta-analysis on the subject using global data to assess the relationship with all-cause mortality or death.


In a rather massive study, they included 10,625,411 participants from Asia, Australia and New Zealand, Europe, and North America who comprised a total of 239 prospective studies

They assessed death, age, sex adjusted hazard ratios relative to BMI.


With a BMI in the normal range of 20-25, all-cause mortality was minimal.

  • BMI 20.0 - 22.5 (HR 1·00, 95% CI 0·98–1·02)
  • BMI 22.5 - 25.0 (HR 1·00, 95% CI 0·99–1·01)

Below the normal range, there was a significant increase in mortality.

  • BMI 18.5 - 20.0, 13% increase in mortality (HR 1.13, 95% CI 1.09-1.17)
  • BMI 15.0 - 18.5, 51% increase in mortality (HR 1.51, 95% CI 1.43-1.59)

A BMI between 25 - 30 is considered overweight and demonstrated an increase in mortality

  • BMI 25.0 - 27.5, 7% increased risk (HR 1.07, 95% CI 1.07-1.08)
  • BMI 27.5 - 30.0, 20% increased risk (HR 1.20, 95% CI 1.18-1.22)

Above 30 is considered the obesity range, which demonstrated dramatic increases in mortality

  • BMI 30.0 - 35.0, 45% increased risk (HR 1.45, 95% CI 1.41-1.48)
  • BMI 35.0 - 40.0, 94% increased risk (HR 1.94, 95% CI 1.87-2.01)
  • BMI 40.0 - 60.0, 176% increased risk (HR 2.76, 95% CI 2.60-2.92)

There was a roughly log-linear relationship with BMI and risk of death after a BMI of 25.0, meaning for every 5 point increase in BMI, your risk of death increased accordingly for all causes included cardiovascular disease, respiratory disease and cancer.

Interestingly, younger obese people in their 30s-40s had a 30% higher risk of death than folks in their 70s and 80s.

Men also had a roughly 20% higher risk of death compared to women.


There is no room for misinterpretation here. This comprehensive meta-analysis clearly demonstrates that people with a BMI outside of the normal range of 20-25 have an increased risk of death.

This is most prominent in the overweight, obese and super obese groups where after controlling for other variables saw as high as a 176% increased risk of death..

Original Article

Body-mass index and all-cause mortality: Individual-participant-data meta-analysis of 239 prospective studies in four continents. (2016). The Lancet. doi:10.1016/s0140-6736(16)30175-1

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