Everyone knows that being obese is very bad for your health. But how overweight do you have to be before you should worry? A new study covering millions of people attempts to answer this question.
The short answer: being a little bit fat isn’t so bad, especially if you’re already a senior citizen, but the fatter you are, the shorter your life expectancy. Let’s dive into the details.
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This left them with nearly 4 million people, of whom 385,879 died at some time during the course of the study. From this large data set, the researchers computed the risk of death as a function of body mass index (BMI).
[Aside: BMI is a simple function of your height and weight. For example, someone who stands 5'11" and weights 170 has a BMI of 23.7. A height of 5'6" and weight of 150 gets you a BMI of 24.2. You can calculate your own BMI using this calculator.]
- underweight, BMI 15–18.5
- normal, BMI 18.5–24.9
- overweight, BMI 25–29.9
- obesity grade 1, BMI 30–34.9
- obesity grade 2, BMI 35–39.9
- obesity grade 3, BMI 40 or above
- BMI 15–18.5: 47% increased risk of death
- BMI 18.5–24.9: no increase (normal)
- BMI 25–29.9: 11% increased risk of death
- BMI 30–34.9: 44% increased risk of death
- BMI 35–39.9: 92% increased risk of death
- BMI 40 or above: 171% increased risk of death
If these numbers seem scary, keep in mind that this is relative risk, not absolute risk. So an 11% increase in risk might mean that your chance of dying increases from 1% to 1.11%; it certainly doesn’t mean you have an 11% risk of dying.