Bariatric surgery leads to long-term remission and reduced incidence of diabetes, hypertension, and dyslipidemia. Short-term studies suggest reduction in specific fat depots may be more predictive of health improvement than BMI.
Visceral, abdominal subcutaneous, epicardial, and liver fat were quantified by non-contrast computed tomography after an average of 11 years follow-up in subjects who did (N=261) or did not (N=243) have gastric bypass surgery. These fat depots were related to changes in diabetes, hypertension and dyslipidemia with and without adjustment for change in BMI and surgical status.
Visceral fat was 42% lower, abdominal subcutaneous fat 20% lower, epicardial fat 30% lower, and liver-to-spleen density ratio 9% higher at follow-up in the surgery group compared with the non-surgery group (all p<0.01). Higher visceral fat at follow-up exam was significantly associated with increased incidence and reduced remission of diabetes, hypertension and dyslipidemia. Abdominal subcutaneous fat was not associated with disease. The liver-to-spleen ratio was only associated with the incidence and remission of hypertriglyceridemia and not with other fat depots. Epicardial fat was related to incidence of high LDL-C and low HDL-C.
Fat depot-specific changes after gastric bypass surgery and their differing associations with disease highlight the importance of adipose tissue and its heterogeneous effects on disease progression. Favorable metabolic health and mortality outcomes observed in patients who undergo surgery-induced weight loss may depend, in part, on long-term reduction of ectopic fat depots.