According to new study conducted by University of Barcelona in Spain healthy fat intake does not cause weight gain.

Mediterranean diet includes foods that are high in fat, however it does not include many foods linked to weight gain, such as sweets and junk food.

The Mediterranean diet is a modern nutritional recommendation originally spread by the dietary patterns of Greece, Southern Italy, and Spain in the 1940s and 1950s.

The research investigated more than 7,400 women and men in Spain, aged between 55 to 80. The participants had one of three eating plans: an unrestricted-calorie Mediterranean diet rich in olive oil; an unrestricted-calorie Mediterranean diet rich in nuts; or a low-fat diet meant to avoid all dietary fat.

More than 90 percent of participants were obese, the study noted.

5 years later, participants assigned to the Mediterranean diet plus extra-virgin olive oil and nuts lost 0.88 kg and 0.40 kg, respectively, while those assigned to low-fat control diet lost 0.60 kg. In a model that adjusted for multiple variables, including baseline body mass index and total energy consumption, those assigned to the Mediterranean diet plus extra-virgin olive oil lost 0.43 kg more weight than did controls, a difference that was statistically significant. For those assigned to the Mediterranean diet supplemented with nuts, the multivariable-adjusted difference in body weight versus the control arm was not statistically outstanding.

"These results have practical implications, because the fear of weight gain from high fat foods need no longer be an obstacle to adherence to a dietary pattern such as the Mediterranean diet, which is known to provide much clinical and metabolic benefit," write Ramon Estruch, MD, PhD, from CIBER OBN-University, Barcelona.

"They are also relevant for public health, because they lend support to not restricting intake of healthy fats in advice for bodyweight maintenance and overall cardiometabolic health, as acknowledged by the Dietary Guidelines for Americans 2015 Advisory Committee," they add.

The autors also discovered that people on the Mediterranean diet also had more vegetables intake, fruit and fish and consumed less meat and dairy products than those on the low-fat diet. This explains why even though they weren't told to eat fewer calories, the people in the Mediterranean group tended to lose slightly more weight than those in the low-fat group.

The report was published June 6 in The Lancet Diabetes & Endocrinology.