What’s your BMI and should you care?


I was reading a post over on Art De Vany’s site this morning about body mass index (BMI), so I thought I would check my own. I used the online tool on the NHS website.

Here’s what the NHS says about BMI

BMI is good way to check if you’re a healthy weight. Use our BMI calculator to check the whole family and find helpful information and advice. BMI is a measure of whether you’re a healthy weight for your height.

Here’s my result. Apparently I’m right at the top end of overweight, with a BMI of 28.1.

Obviously it’s complete rubbish. I’ve got the same BMI as Matthew Pinsent (not now, but when he was on top form winning Gold at the Olympics).

Here’s the BMI of some other people.

Matthew Pinsent
Rowing (Coxless four)
(Overweight: 196cm, 108kg, athlete BMI=28)

James Cracknell
Rowing (Coxless four)
(Overweight: 192cm, 100kg, athlete BMI=27)

Dwain Chambers
Sprinter
(Overweight 5’9″  83kg BMI 25.6)

Usain Bolt
Sprinter
(Overweight 6’4”, 210lbs BMI 26.1)

Asafa Powell
Sprinter
(Overweight 6′, 3″, 198lbs     25.1bmi)

A BMI calculation takes no account of how much of your weight is muscle and how much is fat. A much better guide is the Waist-hip ratio. Which is the ratio of the circumference of the waist to the hips. It is calculated by measuring the smallest circumference of the natural waist, usually just above the belly button, and dividing by the hip circumference at its widest part of the buttocks or hip. The ratio is applied both to women and men.

A WHR of 0.7 for women and 0.9 for men have been shown to correlate strongly with general health and fertility. Women within the 0.7 range have optimal levels of oestrogen and are less susceptible to major diseases such as diabetes, cardiovascular disorders and ovarian cancers. Men with WHRs around 0.9, similarly, have been shown to be more healthy and fertile with less prostate cancer and testicular cancer.

My WHR is 0.9, spot on the ideal for men.

WHR has been found to be a more efficient predictor of mortality in older people than waist circumference or BMI. A study in the Lancet (volume 366) “Obesity and the risk of myocardial infarction in 27 000 participants from 52 countries: a case-control study” showed that if obesity is redefined using WHR instead of BMI, the proportion of people categorised as at risk of heart attack worldwide increases threefold.

Just as worrying is that whilst in middle age being fat is associated with early mortality, diabetes and heart attacks, int he elderly being under weight is a much more serious problem.

A study “Muscle Strength and Body Mass Index as Long-Term Predictors of Mortality in Initially Healthy Men” in this study mortality was followed prospectively over 30 years. Maximal hand grip strength tests and BMI assessments were done at baseline in 1965 to 1970. The participants were 6040 healthy men aged 45 to 68 years at baseline living on Oahu, Hawaii.

The study showed that the mortality rate of those at the ideal and over weight BMI categories where much better than those who were under weight and concluded that:

In healthy middle-aged men, long-term mortality risk was associated with grip strength at baseline, independent of BMI. The possible interpretation of the finding is that early life influences on muscle strength may have long-term implications for mortality. Additionally, higher strength itself may provide greater physiologic and functional reserve that protects against mortality.

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About thegymmonkey

I'm a fitness junkie,interested in injury rehab and get back into competition. View all posts by thegymmonkey

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