Authors: Ramon Estruch, Miguel Angel Martínez-González, Dolores Corella, Jordi Salas-Salvadó, Montserrat Fitó, Gemma Chiva-Blanch, Miquel Fiol, Enrique Gómez-Gracia, Fernando Arós, José Lapetra, Lluis Serra-Majem, Xavier Pintó, Pilar Buil-Cosiales, José V Sorlí, Miguel A Muñoz, Josep Basora-Gallisá, Rosa María Lamuela-Raventós, Mercè Serra-Mir, Emilio Ros
Summary:
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.
Source:
The Lancet Diabetes & Endocrinology; 2016