The authors, from the National Health Research Institutes in Taiwan, found that high blood pressure and blood glucose were associated with an increased risk of mortality in both younger and older individuals, irrespective of gender or body composition.
High blood pressure was associated with an 8.57% risk of mortality and high blood sugar was associated with a 6.49%, compared to a 1.04% increased risk in obese individuals.
The findings are published in the open access journal BMC Public Health.
Dr. Mark Wahlqvist, the corresponding author said: “For adult men and women of predominantly Chinese ancestry, cardio-metabolic risk factors such as abdominal fat, hyperglycemia (high blood sugar), dyslipidemia (abnormal amounts of blood lipids) and high blood pressure exceeded overweight or obese BMIs as predictors of decreased survival. Our findings shed new light on how the known association between BMI and mortality may be altered by cardio-metabolic factors, and thus could help improve strategies for a longer, healthier life.”
The researchers also found the effect of BMI on mortality appeared to vary with age.
For those younger than 40, overweight and obesity were associated with higher mortality risk than that observed in people older than 50, where mortality rates were lowest in overweight individuals and highest in underweight individuals. For those older than 40 years, being underweight increased mortality risk by 51-74%.
Dr. Wahlqvist said: “We were surprised to find that underweight was a more important predictor of reduced survival than overweight or obesity, except in young adults. In turn, older age appears to be protective against the risk posed by higher BMIs. Our findings suggest that weight-management programs may need to be tailored according to age.”
The researchers followed 377,929 participants, aged 20 years or older, registered with MJ Health Screening Center in Taiwan. The overall population risk for high blood pressure was 7.3% - higher than the risk for underweight (5.5%), low normal weight (6.0%) and obese2 (0.4%).
The authors caution that the selection of study participants through a private health screening center may have introduced bias toward higher socioeconomic status and the results may not be generalizable to lower-income groups. Also, since the participants were predominantly of Chinese ethnicity, only a small proportion of them were obese.
As a result, the harmful effects of obesity may have been underestimated, while observational nature study does not allow for conclusions about cause and effect.
Source: BMC Public Health.
"Cardiometabolic disorder reduces survival prospects more than suboptimal body mass index irrespective of age or gender: a longitudinal study of 377,929 adults in Taiwan"
Authors: Chih-Cheng Hsu, et al.