Study reveals how BMI not alone be sufficient indicator of metabolic health

Washington [US], July 10 : According to studies, body mass index (BMI) is not a full indicator of metabolic health, and a substantial number of U.S. individuals with normal BMI are nevertheless obese.

The research was presented at ENDO 2023, the Endocrine Society's annual meeting in Chicago, Ill.

To properly understand the causes of cardio-metabolic illness, the current study emphasises the need of incorporating what proportion of the body is fat, muscle, bone, and water, as well as how much fat is in the belly vs. the thighs.

"We show that there are racial/ethnic differences in body fat, BMI, and body fat distribution which may provide evidence for future studies to further determine if these differences are possible drivers of the racial disparities seen in cardio-metabolic diseases," said Aayush Visaria, M.D., M.P.H., an internal medicine resident at the Rutgers Robert Wood Johnson Medical School in New Brunswick, N.J.

Visaria and colleagues identified non-pregnant U.S. adults aged 20-59 years from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) with whole body DEXA scan data. Their BMI was categorized by ethnicity (non-Asian: underweight 18.5, normal=18.5-24.9, overweight=25-29.9, obese 30 kg/m2, Asian: 18.5, 18.5-22.9, 23-27.4, 27.5+).

The researchers estimated odds of obesity among adults as normal/overweight based on BMI or total body fat percentage (BF per cent) as 25% in male and 32% in female, by race (non-Hispanic White [NHW], non-Hispanic Black [NHB], Asian, Hispanic, and other). They also estimated mean DEXA adiposity measures by race.

They found that nearly 36% had BMI 30 (the traditional definition of obesity) but 74% had obesity per BF per cent. Among normal BMI adults, 44 per cent of non-Hispanic Whites, 27% of NHB, 49% of Hispanic, and 49 per cent of Asians had obesity as per BF per cent. Among normal BMI adults, the mean android-to-gynoid fat ratio was 0.84 for NHW, 0.85 for NHB, 0.89 for Hispanics, and 0.91 for Asians.

Nearly 3 in 4 young-to-middle-aged U.S. adults were considered to have obesity according to BF% from DEXA scans. Asian Americans and Hispanics with seemingly normal BMI were more likely to have obesity, and more likely to have a greater proportion of abdominal fat than non-Hispanic Whites. Non-Hispanic Blacks had significantly lower chances of obesity at normal/overweight BMI ranges, and a lower proportion of abdominal fat.