Growing Evidence that Waist-Hip Ratio Better than
BMI to Predict Elderly Persons Health
UCLA study finds no association between all-cause
mortality and BMI or waist circumference; the link was only with
waist-hip ratio
Sept. 1, 2009 The most commonly used method of
determining obesity is the Body Mass Index (BMI), but a new study says
this may not be the best way to determine obesity for those over age 70.
The ratio of waist size to hip size may be a better indicator of the
health of the elderly, which supports the conclusion of another study
published in 2006.
The waist-to-hip circumference ratio is a better
yardstick for assessing obesity in high-functioning adults between the
ages of 70 and 80, presumably because the physical changes that are part
of the aging process alter the body proportions on which BMI is based,
say UCLA endocrinologists and geriatricians in the latest study on the
subject.
"Basically, it isn't BMI that matters in older
adults it's waist size," said Dr. Preethi Srikanthan, UCLA assistant
professor of endocrinology and the study's lead investigator.
"Other studies have suggested that both waist size
and BMI matter in young and middle-aged adults and that BMI may not be
useful in older adults; this is one of the first studies to show that
relative waist size does matter in older adults, even if BMI does not
matter."
The study by researchers from the David Geffen
School of Medicine at UCLA is published online in the peer-reviewed
journal Annals of Epidemiology.
The 2006 study, by a team based at the London
School of Hygiene & Tropical Medicine, found that older people with high
waist-hip ratios (WHRs) have a higher mortality risk than those with a
high BMI.
Study finds Body Mass Index not the best indicator
of mortality
August 8, 2006
The London findings confirmed that the accepted
guidelines for BMI-based risk categories overestimate the risks of
excess weight in people aged over 75 and are inappropriate for older men
and women. This is a slightly higher age than the new study, which
suggests the WHR should be used for those aged 70 and over.
The London research group also refers to a previous
study that found BMIs of 25-27 not to be a risk factor for all-cause and
cardiovascular mortality in those aged 65 and over.
The dramatic difference in the two studies the
current UCLA report and the 2006 report from London was a finding by
the UK group that their data highlighted the risk of having a low BMI,
with people in the lowest quintile (less than 23 in men and less than
22.3 in women) demonstrating the highest risk of death for total
mortality and for major causes of death.
Using data from the MacArthur Successful Aging
Study - a longitudinal study of high-functioning men and women between
the ages of 70 and 79 - the UCLA researchers examined all-cause
mortality risk over 12 years by BMI, waist circumference and waist-hip
ratio.
They adjusted for gender, race, baseline age and
smoking status. The average age of participants was 74.
Obesity is often associated with premature
mortality because it leads to an increased risk of diabetes, heart
attack, stroke and other major health problems, the study authors say.
The researchers found no association between
all-cause mortality and BMI or waist circumference; the link was only
with waist-hip ratio.
In women, each 0.1 increase in the waist-hip ratio
was associated with a 28 percent relative increase in mortality rate
(the number of deaths per 100 older adults per year) in the group
sampled.
Thus, if the waist-hip ratio rose from 0.8 to 0.9
or from 0.9 to 1.0, it would mean a 28 percent relative increase in the
death rate.
Put another way, if hip size is 40 inches, an
increase in waist size from 32 to 36 inches signaled a 28 percent
relative death-rate increase.
The relationship was not graded in men. Instead
there was a threshold effect:
The rate of dying was 75 percent higher in men with
a waist-hip ratio greater than 1.0 - that is, men whose waists were
larger than their hips - relative to those with a ratio of 1.0 or lower.
There was no such relationship with either waist size or BMI.
The study may have some limitations, the authors
noted. For instance, participants' BMI may be underestimated because
height and weight were self-reported and older adults tend to report
those numbers from their younger, peak years.
Also, waist-hip ratios, waist circumference and BMI
numbers were based on single measurements, limiting the researchers'
ability to gauge how changing body size in old age can affect mortality
risk.
Teresa Seeman and Arun S. Karlamangla, both also of
UCLA, were co-authors on the study.
The National Institute on Aging funded the UCLA
research.
The study carried out at the London School of
Hygiene & Tropical Medicine was published in the American Journal of
Clinical Nutrition in August, 2006.
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Obesity,
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The UCLA Division of Geriatrics, within the
department of medicine at the David Geffen School of Medicine at UCLA
offers comprehensive outpatient and inpatient services at several
convenient locations and works closely with other UCLA programs to
improve and maintain the quality of life of seniors. UCLA geriatricians
are specialists in managing the overall health of people age 65 and
older and treating medical disorders that frequently affect the elderly,
including falls and immobility, urinary incontinence, memory loss and
dementia, arthritis, high blood pressure, heart disease, osteoporosis,
and diabetes. UCLA geriatricians can knowledgably consider and address a
broad spectrum of health-related factors including medical,
psychological and social when treating patients.
Links to More on Senior
Citizens and Obesity in SeniorJournal.com Archives
Sept. 1, 2009 The most commonly used method of
determining obesity is the Body Mass Index (BMI), but a new study says
this may not be the best way to determine obesity for those over age 70.
The ratio of waist size to hip size may be a better indicator of the
health of the elderly, which supports the conclusion of another study
published in 2006.
Obesity,
But Not Overweight, Linked To Cancer and Cardiovascular Deaths