June 08, 2016
3 min read

High-fat Mediterranean diet effects similar to low-fat diet

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Spanish adults at high risk for cardiovascular disease assigned an unrestricted-calorie, high-vegetable-fat Mediterranean diet saw greater decreases in body weight and less gain in central adiposity vs. adults assigned to a control diet and advised to reduce dietary fat, according to results from a 5-year randomized controlled trial.

“More than 40 years of nutritional policy has advocated for a low-fat diet, but we’re seeing little impact on rising levels of obesity,” Ramon Estruch, MD, PhD, senior consultant in the internal medicine department of the Hospital Clinic, University of Barcelona, Spain, said in a press release. “Our study shows that a Mediterranean diet rich in vegetable fats, such as olive oil and nuts, had little effect on body weight or waist circumference compared to people on a low-fat diet.”

Estruch and colleagues analyzed data from 7,447 men and women aged 55 to 80 years with type 2 diabetes and three or more CV risk factors participating in the PREDIMED trial, conducted at 11 hospitals in Spain between 2003 and 2010 (4,282 women; 97% white; > 90% with overweight or obesity). Participants were randomly assigned to one of three interventions: Mediterranean diet supplemented with extra-virgin olive oil (n = 2,543); Mediterranean diet supplemented with nuts (n = 2,454) or a control diet (advice to reduce dietary fat; n = 2,450). Researchers did not advise energy restriction or promote physical activity. Body weight and waist circumference were measured at baseline and yearly for 5 years.

After a mean of 4.8 years, all participants experienced reductions in body weight and slightly increased waist circumference. Adjusted difference in 5-year changes in body weight in the Mediterranean diet with olive oil group was –0.43 kg (95% CI, –0.86 to –0.01; P = .044) vs. controls; adjusted difference in the nut group was –0.08 kg (95% CI, –0.5 to –0.35; P = .73) vs. the control diet group. Adjusted difference in 5-year changes in waist circumference was –0.55 cm (95% CI, –1.16 to –0.06; P = .048) in the olive oil group vs. controls and –0.94 cm (95% CI, –1.6 to –0.27; P = .006) in the nut group vs. controls.

“Despite the high fat content of Mediterranean diet, subjects who followed a Mediterranean diet supplemented with extra-virgin olive oil did not gain weight or increase their waist perimeter throughout the 5 years of the study,” Estruch told Endocrine Today. “To follow a Mediterranean diet reduces the incidence of hard CV outcomes — myocardial infarction, stroke or CV death — by 30%. People may follow this healthy high-fat diet without fear to increase their body weight or their waist perimeter.”

In commentary accompanying the study, Dariush Mozaffarian, MD, of Tufts University Friedman School of Nutrition Science and Policy in Boston, said dietary guidelines should be revised to change “outdated, arbitrary limits” on total fat consumption.

“The fat content of foods and diets is simply not a useful metric to judge long-term harms or benefits,” Mozaffarian wrote. “Energy density and total caloric contents can be similarly misleading. Rather, modern scientific evidence supports an emphasis on eating more calories from fruits, nuts, vegetables, beans, fish, yogurt, phenolic-rich vegetable oils and minimally processed whole grains; and fewer calories from highly processed foods rich in starch, sugar, salt or trans fat.” – by Regina Schaffer

Disclosure: Estruch reports serving on boards of or receiving lecture fees from AstraZeneca, the Beer and Health Foundation, Cerveceros de Espana, the European Foundation for Alcohol Research, Fundación Dieta Mediterránea, Instituto Cervantes, Lilly Laboratories, the Research Foundation on Wine and Nutrition, and Sanofi Aventis; consultancy fees from KAP Corp.; and grant support through his institution from Amgen, Bicentury, Grand Fountaine and Novartis. Mozaffarian reports receiving ad hoc honoraria or consulting fees from AstraZeneca, Boston Heart Diagnostics, DSM, GOED, Haas Avocado Board and Life Sciences Research Organization. He is named on a patent held by Harvard University.