Friday, November 16, 2012

Big Belly = High Risk

"Recent research suggests that even if your weight is in the normal range, if you have a high waist-to-hip ratio, you have a higher risk of death than those considered obese based on BMI
The risk of cardiovascular death was 2.75 times higher, and the risk of death from all causes was 2.08 times higher in people of normal weight with central obesity, compared with those with a normal BMI and normal waist-to-hip ratio
"Research indicates your waist size may also be a more effective measure for assessing obesity-related hypertension risk
"One of the simplest and most effective ways to determine whether or not you may be overweight is by measuring your waist circumference. I compiled a new waist circumference table that will allow you to easily look up your height and see what your ideal waist size and current classification is
"Your waist size is a powerful indicator of insulin sensitivity, as studies clearly show that measuring your waist size is one of the most powerful ways to predict your risk for diabetes."

Interesting for two reasons - one is, it is a possible indicator of why "skinny fat" folks have death risk equivalent to more typically fat folks - a model would be: skinny fat folks have a "lipo-phobic" body type, which does not handle fat storage well. They typically have little subcutaneous fat, little fat on their face, and you'll never see a person with this type of frame (long and lean, aka and ectomorph) on The Biggest Loser. They just can't get that large. But when they eat too much of the stuff that will kill you, they have to sequester all that excess blood sugar somewhere, so eventually it becomes fat stored in the abdominal cavity, making a big belly on an otherwise lean, not obviously fat person. BMI stays low, but health is compromised.

The other reason is that this study was done was to help "public health authorities" identify those at risk at very low cost. BMI can be a health indicator for populations, but even for populations, it's a poor correlate - those with well trained, dense muscles and bones will have a high BMI but low health risk, and the "skinny fat" will have normal BMI but high health risk. IOW - BMI is a crude tool, not applicable to individuals.

There is also the interesting element of the language - clearly stated, this is an observational study, and the language associated with those types of studies reflects that:
"risk of cardiovascular death was 2.75 times higher"
"risk of death from all causes was 2.08 times higher"
And the assignment of causality, or speculation about causality:
"The increased mortality risk accompanying higher ratios of visceral fat ... is likely due to increased insulin resistance."

In short, you can be on the lookout for this language and know this study proves nothing about causality. You can remind yourself that "risk" in this context doesn't have predictive value - it's just epidemiological language about correlation. Knowing this, you can reduce some of the confusing clutter in reporting on science.

What's the takaway? Nothing you don't know. Big bellies are neither attractive nor healthy, but that's already fairly widely accepted. ACSM has been saying for years that abdomenal circumference is an excellent predictor of mortality.  Even if a big belly wasn't a health issue - "nobody wants that."
Eat meat, eggs, vegetables, nuts and seeds, little fruit or starch, no sugar/wheat. 

The real takeaway for me is that folks who are starting a diet/health program need a measure for their belly as much as, or more than, a scale.  Weight loss without belly loss isn't good, and belly loss without weight loss is good.

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