Randomized trial of weight-loss-diets for young adults varying in fish and fish oil content

Unit for Nutrition Research, Department of Food Science and Human Nutrition, Landspitali University Hospital, University of Iceland, Eiriksgata-29, 101 Reykjavik, Iceland.
International Journal of Obesity (Impact Factor: 5.39). 11/2007; 31(10):1560-6. DOI: 10.1038/sj.ijo.0803643
Source: PubMed

ABSTRACT To investigate the effect of including seafood and fish oils, as part of an energy-restricted diet, on weight loss in young overweight adults.
Randomized controlled trial of energy-restricted diet varying in fish and fish oil content was followed for 8 weeks. Subjects were randomized to one of four groups: (1) control (sunflower oil capsules, no seafood); (2) lean fish (3 x 150 g portions of cod/week); (3) fatty fish (3 x 150 g portions of salmon/week); (4) fish oil (DHA/EPA capsules, no seafood). The macronutrient composition of the diets was similar between the groups and the capsule groups, were single-blinded.
A total of 324 men and women aged 20-40 years, BMI 27.5-32.5 kg/m(2) from Iceland, Spain and Ireland.
Anthropometric data were collected at baseline, midpoint and endpoint. Confounding factors were accounted for, with linear models, for repeated measures with two-way interactions. The most important interactions for weight loss were (diet x energy intake), (gender x diet) and (gender x initial-weight).
An average man in the study (95 kg at baseline receiving 1600 kcal/day) was estimated to lose 3.55 kg (95% CI, 3.14-3.97) (1); 4.35 kg (95% CI, 3.94-4.75) (2); 4.50 kg (95% CI, 4.13-4.87) (3) and 4.96 kg (95% CI, 4.53-5.40) on diet (4) in 4 weeks, from baseline to midpoint. The weight-loss from midpoint to endpoint was 0.45 (0.41-0.49) times the observed weight loss from baseline to midpoint. The diets did not differ in their effect on weight loss in women. Changes in measures of body composition were in line with changes in body weight.
In young, overweight men, the inclusion of either lean or fatty fish, or fish oil as part of an energy-restricted diet resulted in approximately 1 kg more weight loss after 4 weeks, than did a similar diet without seafood or supplement of marine origin. The addition of seafood to a nutritionally balanced energy-restricted diet may boost weight loss.

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    • "Apart from quantity, the quality of dietary proteins is of significance in the prevention of obesity. Prospective cohort studies have demonstrated that consumption of fish as a part of healthy diet is associated with lower body weight (Schulze et al. 2006; Shubair et al. 2005) and randomized controlled studies show that the inclusion of fish in energy-restricted diets resulted in greater weight loss compared to control diets without seafood (Thorsdottir et al. 2007; Ramel et al. 2009). In addition, incorporation of a daily fish meal into a weight-loss regimen was more effective than either fish consumption or weight loss alone at improving glucose-insulin metabolism and dyslipidemia (Mori et al. 1999). "
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    • "Animal models have shown significant reductions in fat mass when dietary n-3 PUFAs, namely eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), are substituted for saturated fats (Hainault et al. 1993), monosaturated fats (Su and Jones 1993), and n-6 polyunsaturated fats (Jones 1989), after controlling for caloric intake. These findings have largely been confirmed by human studies (Thorsdottir et al. 2007); however, information regarding whether the anti-obesity effects attributed to n-3 PUFA is dependent upon a specific genotype remains limited (Jourdan et al. 2011). Knowledge about the interplay between genetic factors and consumption of n-3 PUFA in isolated populations with widely varying n-3 PUFA intake may facilitate the choice of more effective and specific measures of obesity prevention based upon individualized genetic makeup. "
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    • "Anthropometric (height [Leicester height measure; Seca, Birmingham UK], body weight [calibrated Seca 888 scales; Seca), waist circumference [Seca measuring tape], and BMI), blood pressure (Medisana blood pressure monitor; Medisana, Dusseldorf, Germany), and body composition by bioimpedance analysis [BIA; Bodystat 1500, Isle of Man, UK]) measurements were taken using standard protocols [33] and ensured that all subjects were adequately hydrated before BIA assessment. Subjects completed a health and lifestyle questionnaire, which included information on habitual physical activity (PA) for calculation of metabolic equivalent (MET) scores (in hours per week). "
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