a few extra pounds may not hurt older people

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Issue 543

A Few Extra Pounds May Benefit Older People

A little excess weight after age 70 could do the body some good, according

to results of a study involving 9,000 older patients. Overweight study

participants

had a 13% lower risk of death compared with normal-weight participants....

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Leon Flicker, PhD, of the Western Australian Center for Health and Aging in

Perth, and colleagues found that, overweight participants in the cohort

study

had the lowest 10-year mortality. Normal-weight and obese participants ages

70 to 75 had a similar and slightly higher risk of death.

The findings add to evidence suggesting that being overweight in older age

is not such a bad thing and might even be beneficial.

The researchers concluded that, " These results lend further credence to

claims that the body mass index [bMI] thresholds for overweight and obese

are overly

restrictive for older people. " The authors also found that a sedentary

lifestyle doubled the mortality risk for older women but did not affect

survival

of older men.

The World Health Organization has established four BMI thresholds to

characterize body weight:

list of 4 items

<18.5 kg/m2, underweight

18.5 to 24.9 kg/m2, normal weight

25 to 29.9 kg/m2, overweight

?30 kg/m2, obese

list end

The authors noted that the thresholds were derived primarily from studies of

younger and middle-age adults. Whether the cut points for overweight and

obese

are appropriate for older individuals has remained unclear.

Two systematic reviews and a meta-analysis showed no increased mortality

risk associated with a BMI in the overweight range for older people (Arch

Intern

Med 2001; 161: 1194-1203, Obesity Rev 2007; 8: 41-59). However, methodologic

differences complicated the comparison of different studies.

So they sought to address some of the uncertainty by analyzing data from two

large Australian cohort studies involving more than 9,000 individuals ages

70 to 75 (4,677 men, 4,563 women).

The principal objectives were to determine the BMI threshold associated with

the lowest mortality in older people and to determine whether the

relationship

between BMI and mortality differed between men and women.

Data for the analysis came from self-reported measures of height and weight,

which the authors used to calculate BMI for the study participants.

Participants

also provided demographic, lifestyle, and health information.

Using the WHO criteria for BMI, the authors found that 1.3% of men and 3.1%

of women were underweight; 43.5% of men and 50.3% of women were normal

weight;

44.3% of men and 33.5% of women were overweight; and 11% of men and 13.1% of

women were obese.

During 10 years of follow-up, overweight study participants had a 13% lower

risk of death compared with normal-weight participants (HR 0.87, 95% CI 0.78

to 0.94). Obese participants had a mortality risk similar to that of

normal-weight participants (HR 0.98, 95% CI 0.85 to 1.11).

Self-reported sedentary lifestyle doubled the mortality risk for women

across all BMI categories (HR 2.08, 95% CI 1.79 to 2.41). In contrast,

sedentary

lifestyle increased the mortality risk for men by 28% (HR 1.28, 95% CI 1.14

to 1.44).

Separate analyses involving common causes of death, such as cardiovascular

disease and cancer, showed similar relationships between BMI and mortality

risk.

" Even after removing the effects of early mortality, those who were

overweight were still at lowest risk, a finding consistent with the

observation that

weight loss in older age groups is associated with greater mortality, " the

authors wrote.

" Overweight older people are not at greater mortality risk, and there is

little evidence that dieting in this age group confers any benefit, " they

added.

Practice Pearls:

list of 2 items

Explain to patients that this study suggests that overweight older people

do not have an increased mortality risk.

Note that the association between BMI and mortality in older people is

controversial.

list end

Flicker L, et al " Body mass index and survival in men and women aged 70 to

75 " J Am Soc Geriatr Soc 2010; DOI: 10.1111/j.1532-5415.2009.02677.x.