¹Laboratoire de Nutrition et Clinique Médicale A, J.E. 313, Université François Rabelais, 37000 Tours, France

²Laboratoire de Nutrition Humaine, BP 321, 63009 Clermont-Ferrand, France

³Groupe Danone, Direction scientifique, 7 rue de Téhéran, 75008 Paris, France

Correspondence: Dr C Couet, Laboratoire de Nutrition, Hôpital Bretonneau, 2, Boulevard Tonnellé, 37044 TOURS CEDEX, France

OBJECTIVE: To investigate whether the substitution of fish oil for visible fats in a control diet (52% carbohydrates, 16% protein, 32% fat; P:S 0.2) influences body fat mass and substrate oxidation in healthy adults. DESIGN: Six volunteers (5 men; 23±2 y; BMI: 21.9±1.6) were fed a control diet (C) ad libitum during a period of three weeks and, 10-12 weeks later, the same diet where 6 g/d of visible fat were replaced by 6 g/d of fish oil (FO) for another three weeks. RESULTS: Energy intakes (IKA-calorimeter) were unchanged. Body fat mass (Dual-energy X-ray absorptiometry) decreased with FO (-0.88±0.16 vs-0.3±0.34 kg; FO vs C; P<0.05). When adjusted for lean body mass (Ancova), resting metabolic rate (indirect calorimetry) was unchanged. Basal respiratory quotient decreased with FO (0.815±0.02 vs 0.834±0.02; P<0.05) and basal lipid oxidation increased with FO (1.06±0.17 vs 0.87±0.13 mg kg^-1 min^-1; P<0.05). CONCLUSION: Dietary FO reduces body fat mass and stimulates lipid oxidation in healthy adults.

n-3 long-chain polyunsaturated fatty acids; fish oil; energy metabolism; body composition; resting metabolic rate; human