Facilitated long chain fatty acid uptake by adipocytes remains upregulated relative to BMI for more than a year after major bariatric surgical weight loss

Objective This study examined whether changes in adipocyte long chain fatty acid (LCFA) uptake kinetics explain the weight regain increasingly observed following bariatric surgery. Methods Three groups (10 patients each) were studied: patients without obesity (NO: BMI 24.2 ± 2.3 kg m^-2); patients with obesity (O: BMI 49.8 ± 11.9); and patients classified as super-obese (SO: BMI 62.6 ± 2.8). NO patients underwent omental and subcutaneous fat biopsies during clinically indicated abdominal surgeries; O were biopsied during bariatric surgery, and SO during both a sleeve gastrectomy and at another bariatric operation 16 ± 2 months later, after losing 113 ± 13 lbs. Adipocyte sizes and [³H]-LCFA uptake kinetics were determined in all biopsies. Results V_max for facilitated LCFA uptake by omental adipocytes increased exponentially from 5.1 ± 0.95 to 21.3 ± 3.20 to 68.7 ± 9.45 pmol/sec/50,000 cells in NO, O, and SO patients, respectively, correlating with BMI (r = 0.99, P < 0.001). Subcutaneous results were virtually identical. By the second operation, the mean BMI (SO patients) fell significantly (P < 0.01) to 44.4 ± 2.4 kg m^-2, similar to the O group. However, V_max (40.6 ± 11.5) in this weight-reduced group remained ∼2X that predicted from the BMI:V_max regression among NO, O, and SO patients. Conclusions Facilitated adipocyte LCFA uptake remains significantly upregulated ≥1 year after bariatric surgery, possibly contributing to weight regain.