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Mediterranean diet outperforms low-fat diet for weight loss, say researchers

A study finds that eating healthy fats present in a Mediterranean diet leads to greater weight loss compared to a low-fat diet.
The UK’s official guidelines regarding diet, including for people with diabetes, has been to eat a high-carb, low-fat diet for over 40 years. But these guidelines are now being challenged, and this new study highlights that these guidelines have created a fear of the Mediterranean diet.
The Mediterranean diet is known to have many health benefits, such as improved blood glucose levels, which can help people with diabetes. This new study, published in The Lancet Diabetes and Endocrinology journal, provides more evidence that the fats from fish, nuts and phenolic-rich vegetable oils which are eaten in a Mediterranean diet are much healthier than following a low-fat diet.
Lead author Dr Ramon Estruch, CIBER OBN-University of Barcelona, Spain explained: “Our 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 people on a low-fat diet.
“The Mediterranean diet has well-known health benefits and includes healthy fats such as vegetable oils, fish and nuts. Our 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.”
Long-term study
The long-term study was conducted in 11 Spanish hospitals during 2003-2010. Overall, 7,447 participants aged 55-80 were recruited, all of whom had type 2 diabetes or high cardiovascular risk. More than 90 per cent were overweight or obese, which significantly increases the risk of type 2 diabetes.
The participants 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 all dietary fat was avoided. All participants were given personalised dietary advice by trained dieticians and adhered to their diets well.
After five years, the low-fat diet group decreased their total fat intake from 40% to 37.4%, whereas total fat increased slightly in both Mediterranean diet groups. The percentage of energy intake from protein and carbohydrate decreased in both Mediterranean diet groups.
While all three groups lost weight, the greatest weight loss occurred in the Mediterranean diet with olive oil group. All three groups had increased waist circumferencewaist circumference, but those in the low-fat diet group had the greatest increase.
Professor Dariush Mozaffaria, Friedman School of Nutrition Science and Policy at Tufts University, Bosto, US said in a linked editorial: “Dietary guidelines should be revised to lay to rest the outdated, arbitrary limits on total fat consumption. Calorie-obsessed caveats and warnings about healthier, higher-fat choices such as nuts, phenolic-rich vegetable oils, yoghurt, and even perhaps cheese, should also be dropped.
“We must abandon the myth that lower-fat, lower-calorie products lead to less weight gain. Rather, modern scientific evidence supports an emphasis on eating more calories from fruits, nuts, vegetables, beans, fish, yoghurt, phenolic-rich vegetable oils, and minimally processed whole grains; and fewer calories from highly processed foods rich in starch, sugar, salt, or trans-fat.”

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