Research press release


Nature Aging

Aging: Rethinking optimal BMI for octogenarians in China

中国で2万7000人以上が参加した観察研究から、80歳以上の人々において、過体重や軽度の肥満が死亡率低下と関連していることを明らかにした論文が、Nature Aging に掲載される。この知見は、80歳以上の人々を対象とした最適体重に関する公衆衛生上の勧告を上方修正する必要がある可能性を示唆している。ただし、異なる地域の人々を対象に加えて、さらなる研究を実施する必要がある。


今回、Xiaoming Shiたちは、高齢者におけるBMIと健康転帰と死亡率の関係についての理解を深めるため、中国で実施された観察研究の一環として、80歳以上の参加者2万7026人(平均年齢92.7歳)を最長20年間追跡調査して収集したデータを分析した。Shiたちは、この年齢層の人々の死亡のリスク(特に非心血管疾患による死亡リスク)がBMI値の増加とともに低下し、BMIの最適値が過体重から軽度の肥満の範囲にあることを明らかにした。同様の関係が、胴囲(腹部脂肪の蓄積の代理指標)についても観察された。


Being overweight or mildly obese is associated with reduced mortality in those aged over 80 in China, according to an observational study involving over 27,000 individuals published in Nature Aging. The findings suggest that public health recommendations for optimal weights may need to be revised upward in this age group. Although further studies involving people from different geographies are needed.

The effects of age-related changes in body mass index (BMI) on health are not well understood. There is some evidence for an ‘obesity paradox’ in adults over the age of 65, in which those with a BMI in the overweight-to-mildly obese range tend to experience better health outcomes and lower mortality than their leaner counterparts. However, optimal BMI recommendations have been established on the basis of large-scale epidemiological studies of the general population that tend to poorly represent older individuals, and in particular the oldest old — those aged 80 and over.

To better understand the relationship between BMI, health outcomes and mortality in older adults, Xiaoming Shi and colleagues analysed data collected from 27,026 individuals (mean age of 92.7 years) in their ninth decade or older (aged 80 and over), who were followed for up to 20 years as part of an observational study in China. The authors reveal that in this age group, the risk of mortality — in particular from non-cardiovascular disorders — decreased with increasing BMI values and that the optimal BMI was situated in the overweight-to-mildly obese range. A similar relationship was observed for waist circumference, which is a proxy for the accumulation of abdominal fat.

The authors conclude that these findings support the existence of an obesity paradox in the oldest in China, suggesting that public health recommendations on what is an optimal BMI may not be appropriate for this section of the population.

doi: 10.1038/s43587-022-00201-3


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