Foods, nutrients or whole diets: effects of targeting fish and LCn3PUFA consumption in a 12mo weight loss trial

Background There is some evidence in the literature that emphasising fish consumption may assist with weight loss. The aim was to assess the effects of advice to consume 2 fish meals per week in a weight loss diet. Methods A parallel randomised placebo-controlled trial was conducted in 118 obese Australian adults (mean BMI +/- SD 31.3 +/- 3.5 kg/m2; mean age +/- SD 45 +/- 10 y; 28% male). Participants received low calorie dietary advice + placebo (1 g olive oil; Control), low calorie dietary advice emphasising fish + placebo (Fish), or low calorie dietary advice emphasising fish diet + LCn3PUFA supplements (Fish + S). Individualised advice targeted 2 MJ energy deficit (30%E fat, 45%E carbohydrate and 25%E protein) with or without two servings (180 g) fatty fish/wk. Results All groups lost weight at 12 months (Control -4.5 kg vs. Fish -4.3 kg vs. Fish + S -3.3 kg; p < 0.001) and percentage body fat (Control: -1.5% vs. Fish: -1.4% vs. Fish + S: -0.7%; p < 0.001) but there were no significant differences between groups. Cardiovascular disease risk factors changed as expected from weight loss. Conclusions Advice to consume 2 fish meals per week did not enhance the effects on weight loss of a healthy low calorie diet.