A non-calorie restricted Mediterranean diet high in vegetable fats such as olive oil or nuts does not lead to significant weight gain, say a new study.
Researchers found the current health guidelines that recommend a low-fat, low-calorie diet create unnecessary fear of healthy fats present in a Mediterranean diet. Accumulating scientific evidence suggests that total fat content is not a useful measure of harms or benefits of food, and that fats from nuts, fish and phenolic-rich vegetable oils are healthier than fats from meat and processed foods.
Lead author Dr. Ramon Estruch, CIBER OBN-University of Barcelona, Spain, said the study shows that a Mediterranean diet rich in vegetable fats such as olive oil and nuts had little effect on bodyweight or waist circumference compared to the people on a low-fat diet. He added the Mediterranean diet has well-known health benefits and includes healthy fats such as vegetable oils, fish and nuts.
The findings certainly do not imply that unrestricted diets with high levels of unhealthy fats such as butter, processed meat, sweetened beverages, deserts or fast-foods are beneficial.
The research, conducted in 11 hospitals in Spain during 2003-2010, included 7447 participants (men and women) aged 55-80 who were randomly assigned to one of three groups – an unrestricted-calorie Mediterranean diet rich in olive oil, an unrestricted-calorie Mediterranean diet rich in nuts or a low-fat diet where the advice was to avoid all dietary fat. Trained dieticians gave personalised advice to all the participants.
After 5 years, the total fat intake had decreased in the low-fat diet group (from 40% to 37.4 %) and had slightly increased in both Mediterranean diet groups (40% to 41.8% in olive oil; 40.4% to 42.2 % in nuts). The percentage of energy intake from protein and carbohydrate decreased in both Mediterranean diet groups.
On an average, the participants in all three groups lost some weight with the greatest weight loss seen in the Mediterranean diet with olive oil group compared to the low-fat diet group.