| Abnormalities in essential fatty acid (EFA) metabolism and distribution have been reported in genetically obese rodents and in humans. This study used gamma-linolenate (GLA) as a metabolic intervention to determine if it suppressed weight regain following major weight loss achieved by a very low calorie diet (VLCD). Fifty post-obese humans were randomized into a double-blind study and given either 890 mg/d of GLA (5 g/d borage oil) or 5 g/d olive oil (controls) for 1 year. Body weight and composition and fasting serum and adipose fatty acids were assessed at 0, 3, 12 and 33 months. After 12 subjects in each group had completed one year of supplementation, a difference in weight regain (P<0.03) between the groups was noted, and the initial study was terminated. Unblinding revealed weight regains of 1.8+/-1.6 kg with GLA and 7.6+/-2.1 kg in controls for the 13 and 17 subjects, respectively, who had completed a minimum of 50 weeks in the study. Body fat regains were 0.9+/-1.4 kg and 6.1+/-1.8 kg for the GLA and control groups, respectively. The remaining 10 GLA and 6 control subjects did not differ in weight regain at the initial study termination. Since GLA supplementation significantly reduced weight regain after 1 year, a subgroup from both the GLA (n=9) and the original control (n=14) populations either continued or crossed over to borage oil supplementation for an additional 21 months. Interim weight regains between 15-33 months were 6.48+/-1.79 kg and 6.04+/-2.52 kg for the original GLA and control groups, respectively. GLA supplementation resulted in significant accumulation of GLA in all lipid pools except serum PL, accumulation of di-homo-gamma-linolenate in all lipid pools, and an increase in arachidonate in all lipid pools except serum free fatty acids. Oleate decreased significantly in adipose triglycerides and in serum PL and CE fractions. Despite administering GLA for 33 months, neither adipose nor serum ARA increased beyond levels observed after one year of supplementation. In conclusion, GLA reduced weight regain in humans following a VLCD, suggesting a role for EFA in fuel partitioning in humans prone to obesity. |
