OBESITY AND WEIGHT-LOSS ALTER SERUM POLYUNSATURATED LIPIDS IN HUMANS

Serum omega-6 (n - 6) fatty acids were assessed in 12 obese women during an outpatient very-low-calorie diet (VLCD). Ten subjects (S10) achieved a mean weight loss of 17 kg over 3-5 mo (initial weight-for-height 157%). Serum was obtained before (baseline) and monthly during the VLCD and from five of them (S5) after 2-3 mo of weight stability (refed) at 21 kg of loss. At baseline for S10, the serum phospholipid (PL) 20: 4-omega-6 was 9.16 wt% and differed from normal (12.81 wt%) by P < 0.0001, but cholesterol ester (CE) 20:4-omega-6 did not differ from normal. During 3 mo of VLCD, the S10 serum PL and CE 18: 2-omega-6 fell (P < 0.005 and 0.0001, respectively). Serum PL 20:4-omega-6 rose to normal during VLCD months 1-3 (P < 0.01) while the serum CE 20:4-omega-6 rose above normal (P < 0.0002). During the VLCD, S5 results paralled S10. However when refed, S5 PL and CE 18:2-omega-6 and 20:4-omega-6 all reverted to baseline (PL 20:4-omega-6 below normal, P < 0.001). Serum PL 20:4-omega-6 is low in moderate obesity, corrects to normal during a VLCD, but regresses to the prediet abnormality after weight loss.