Effects of omega-3 supplementation in combination with diet and exercise on weight loss and body composition.

Randomized, placebo-controlled 6-month trial in sedentary, otherwise healthy men and women aged 30-60 years with BMI 26-40 recruited from the general population. Participants received diet and exercise counseling alongside supplementation; 64 participants were randomized to the omega-3 arm, and 81 participants completed the 24-week study overall.

Omega-3 fatty acids were given orally as 5 capsules daily for 6 months, providing 3.0 g/day EPA plus DHA in an EPA:DHA 5:1 ratio. Capsules were taken with two meals daily; the comparator received 5 placebo capsules daily containing soybean and corn oil.

Omega-3 supplementation did not augment weight loss when added to diet and exercise in overweight/obese adults. At week 24, both groups lost about 0.5% of body weight, and the between-group difference in weight change was 0.61 b1 0.58 kg (P = 0.29). Triglycerides decreased by 0.20% in both groups, and LDL cholesterol decreased by 9 mg/dL in the placebo group. Compliance was similar between groups (79.4 b1 26.6% vs 82.8 b1 19.6%), and five gastrointestinal adverse events occurred overall (3 omega-3, 2 placebo) with resolution after administration changes.

The trial had a modest sample size, a 27% dropout rate, and only 24 weeks of follow-up, which limits precision and longer-term inference. Intensive diet and exercise cointervention in both arms and reliance on self-reported logs for some behavioral outcomes may have reduced the ability to isolate a supplement effect.