Monday, September 19, 2016

Is It Okay To Be A Little Bit Fat? A New Study Offers An Answer

Well at BMI of  29 I am overweight, still working on that, 10,000 steps a day allows me to continue my social dinners and wine parties and not gain weight at least.
http://www.forbes.com/sites/stevensalzberg/2016/09/19/is-it-okay-to-be-a-little-bit-fat-a-new-study-offers-an-answer/#66f43b595005
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.
Also on Forbes:
The new study, published in The Lancet, is a combined evaluation (a meta-analysis) of 239 studies that included over 10 million people from four continents: Asia, Australia, Europe and North America. All the studies followed their subjects for a long time, averaging nearly 14 years of observation. The authors (a large consortium called “The Global BMI Mortality Collaboration”) wanted to exclude people who might have already been sick, so their study only looked at people who (a) had never smoked, and (b) who lived at least five years after the study began.


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.]
Recommended by Forbes
The study divided people into six groups:
  • 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
The main outcome that they studied was mortality (death) from any cause. Of course, one can argue that this is too simplistic, since if someone dies from, say, an auto accident, it probably wasn’t due to their weight. But the results were consistent across all four continents, which argues that the study design was probably good. Here are the main findings for each group:
  • 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

Another way to describe these hazard ratios is this: with a BMI above 40, people are 2.71 times as likely to die during any particular time period as people with a normal BMI.
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.

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