RETRACTED: Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: a prespecified secondary outcomes analysis of the PREDIMED randomised controlled trial (Publication with Expression of Concern. See vol. 6, pg. 763, 2018) (Retracted article. See vol. 7, pg. 334, 2019)

Background Because of the high density of fat, high-fat diets are perceived as likely to lead to increased bodyweight, hence health-care providers are reluctant to recommend them to overweight or obese individuals. We assessed the long-term effects of ad libitum, high-fat, high-vegetable-fat Mediterranean diets on bodyweight and waist circumference in older people at risk of cardiovascular disease, most of whom were overweight or obese. Methods PREDIMED was a 5 year parallel-group, multicentre, randomised, controlled clinical trial done in primary care centres affiliated to 11 hospitals in Spain. 7447 asymptomatic men (aged 55-80 years) and women (aged 60-80 years) who had type 2 diabetes or three or more cardiovascular risk factors were randomly assigned (1: 1: 1) with a computer-generated number sequence to one of three interventions: Mediterranean diet supplemented with extra-virgin olive oil (n=2543); Mediterranean diet supplemented with nuts (n=2454); or a control diet (advice to reduce dietary fat; n=2450). Energy restriction was not advised, nor was physical activity promoted. In this analysis of the trial, we measured bodyweight and waist circumference at baseline and yearly for 5 years in the intention-to-treat population. The PREDIMED trial is registered with ISRCTN.com, number ISRCTN35739639. Findings After a median 4.8 years (IQR 2.8-5.8) of follow-up, participants in all three groups had marginally reduced bodyweight and increased waist circumference. The adjusted difference in 5 year changes in bodyweight in the Mediterranean diet with olive oil group was -0.43 kg (95% CI -0.86 to -0.01; p=0.044) and in the nut group was -0.08 kg (-0.50 to 0.35; p=0.730), compared with the control group. The adjusted difference in 5 year changes in waist circumference was -0.55 cm (-1.16 to -0.06; p=0.048) in the Mediterranean diet with olive oil group and -0.94 cm (-1.60 to -0.27; p=0.006) in the nut group, compared with the control group. Interpretation A long-term intervention with an unrestricted-calorie, high-vegetable-fat Mediterranean diet was associated with decreases in bodyweight and less gain in central adiposity compared with a control diet. These results lend support to advice not restricting intake of healthy fats for bodyweight maintenance.