Higher adiposity is causally associated with a higher risk of infection-related mortality in Mexican adults, with the strongest association for fat-mass percentage and associations consistent across six infection subtypes.
Genetically predicted fat-mass percentage (FM%) showed the strongest association with infection-related mortality among all adiposity markers studied.
Hip circumference showed the weakest association with infection-related mortality among all adiposity markers.
BMI was causally associated with infection-related mortality, and its association was partially attenuated after adjustment for waist and hip circumference.
Waist circumference's association with infection-related mortality was substantially reduced after adjustment for BMI and hip circumference.
Associations between genetically predicted adiposity and infection-related mortality were consistent across six distinct infection subtypes.
Trans-ancestry Mendelian randomization instruments for four adiposity traits explained between 1.6% and 3.5% of the variance in the respective adiposity markers.
The study was conducted among 126,491 Mexican adults over approximately 20 years, making it one of the largest MR studies of adiposity and infection mortality in a Latin American population.
This research suggests that having higher levels of body fat causally increases the risk of dying from infections in Mexican adults. Using a technique called Mendelian randomization — which uses genetic variants as proxies for lifelong exposure to higher body fat levels, reducing the risk of confounding — researchers studied over 126,000 Mexican adults over about 20 years, during which nearly 2,600 people died from infections between ages 35 and 74. They found that all four measures of adiposity (BMI, body fat percentage, waist circumference, and hip circumference) were associated with higher infection death risk, with body fat percentage showing the strongest link (more than double the risk per standard deviation increase) and hip circumference showing the weakest link. Importantly, the increased risk was not specific to any one type of infection — it was seen consistently across respiratory infections, urinary tract infections, gastrointestinal infections, sepsis, skin and bone infections, and other infection types. When the researchers looked at the different adiposity measures together (adjusting each for the others), they found that general fatness (measured by BMI and fat-mass percentage) had effects somewhat independent of where fat is distributed, while hip circumference's apparent association largely disappeared once overall and waist fat were accounted for. This suggests that overall body fatness, rather than fat in specific areas, may be the primary driver of infection mortality risk. These findings matter because Mexico has high rates of obesity and also bears a considerable burden of infection-related deaths. This research suggests that population-level efforts to reduce obesity and excess body fat in Mexico — through public health policies, diet, and physical activity programs — could potentially reduce deaths from infections, not just from the cardiovascular and metabolic diseases that obesity is more commonly linked to.
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Upload Your LabsLawal L, Trichia E, Alegre-Díaz J, Baca P, Barerra E, González-Carballo C, et al.. (2026). Adiposity and infection-related mortality: Mendelian randomization study of 126 000 Mexican adults.. International journal of epidemiology. https://doi.org/10.1093/ije/dyag197