Association Between Body Fat and Risk of All-Cause Mortality

Highlights

This systematic review and dose-response meta-analysis evaluated the relationships of body fat percentage, fat mass index, and visceral fat and subcutaneous adipose tissue masses with the risk of all-cause mortality.
A 10% increase in body fat content was associated with an 11% higher relative risk of all-cause mortality in the general adult population. Higher fat mass and visceral fat mass were also associated with higher mortality. Greater subcutaneous adipose tissue mass was associated with lower mortality.
Higher body fat content, particularly fat mass and visceral fat mass, are associated with the risk of all-cause mortality.

Background/objectives

Our objective was to evaluate the relationships between body fat percentage (BF), fat mass (FM), fat mass index (FMI) and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) with the risk of mortality from all causes.

Methods

We systematically searched PubMed, Scopus, and Web of Science through June 2021. We selected prospective cohorts of the relationship between body fat and all-cause mortality risk in the general population. We applied random effects models to calculate relative risks (RR) and 95% CIs.

Results

A total of 35 prospective cohort studies with 923,295 participants and 68,389 deaths were identified . The HRs for all-cause mortality for a 10% increase in BF were 1.11 (95% CI: 1.02, 1.20; I2 = 93%, n = 11) in the general adult population and 0 .92 (95% CI: 0.79, 1.06;I2 = 76%, n = 7) in adults over 60 years of age.

The HRs were 1.06 (95%CI: 1.01, 1.12; I2 = 86%, n = 10) for a 5 kg increase in FM, 1.11 (95%CI: 1.06, 1 .16; I2 = 79%, n = 7) for an increase of 2 kg/m2 in FMI, and 1.17 (95% CI: 1.03, 1.33; I2 = 72%, n = 8) and 0.81 (0.66, 0.99; I2 = 59%, n = 6) for a 1-SD increase in VAT and SAT, respectively.

There was a J-shaped association between BF% and FM and the risk of all-cause mortality, with the lowest risk at BF% of 25% and FM of 20 kg. In subgroup analyses, although there was little evidence of heterogeneity between subgroups, the positive associations observed were more pronounced in studies that had longer duration, excluded participants with prevalent cardiovascular disease and cancer at baseline, with adjustment by smoking or restricted to those who had never smoked, and less pronounced in studies that adjusted for possible intermediaries, suggesting an impact of reverse causality, confounding, and over-adjustment in some of the studies.

Conclusions

Higher body fat content was associated with a higher risk of J-shaped mortality. Any future studies should further evaluate the impact of reverse causality and residual confounding on these associations.

Association Between Body Fat and Risk of All-Cause Mortality

Higher visceral fat content is associated with the risk of all-cause mortality.