Obesity and weight loss alter serum polyunsaturated lipids in humans

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Abstract
Serum ω6 (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: 4ω6 was 9.16 wt% and differed from normal (12.81 wt%) by P < 0.0001, but cholesterol ester (CE) 20:4ω6 did not differ from normal. During 3 mo of VLCD, the S10 serum PL and CE 18: 2ω6 fell (P < 0.005 and 0.0001, respectively). Serum PL 20:4ω6 rose to normal during VLCD months 1-3 (P < 0.01) while the serum CE 20:4ω6 rose above normal (P < 0.0002). During the VLCD, S5 results paralleled S10. However when refed, S5 PL and CE 18:2ω6 and 20:4ω6 all reverted to baseline (PL 20:4ω6 below normal, P < 0.001 ). Serum PL 20:4ω6 is low in moderate obesity, corrects to normal during a VLCD, but regresses to the prediet abnormality after weight loss.