In 5,674 US adults followed a median of 6.75 years (373 deaths), people with both abdominal obesity (measured by sagittal abdominal diameter, SAD) and low relative grip strength had the highest all-cause mortality risk (HR 1.97; 95% CI 1.41-2.75). Dynapenia alone carried an HR of 1.60, while abdominal obesity alone showed no significant association. HbA1c and the systemic immune-inflammation index statistically explained 13.7% and 5.8% of the dynapenic obesity link; combined with elevated HbA1c or SII, hazards reached 2.53 and 3.11.
The most useful signal here is the null result for abdominal obesity alone: once muscle strength is accounted for, belly fat by itself did not predict death. That fits the broader obesity-paradox literature, where adiposity looks benign or protective in older adults until weakness is considered. Grip strength normalized to body size is a cheap, clinic-ready measure, and SAD needs only a caliper and a supine patient, so this phenotype is practical to screen for. The practical takeaway for adults is that resistance training and preserving muscle matter at least as much as shedding fat, and that weight loss strategies should avoid sacrificing lean mass. Limitations are real: observational design, only 373 deaths, a single baseline measurement, and mediation estimates that are exploratory and cannot prove HbA1c or inflammation sit on the causal path. Mediation shares of 6-14% leave most of the excess risk unexplained. Confirmatory rather than paradigm-shifting, but it strengthens the case for pairing strength testing with body-composition screening.