Eating high-fat food should not worry you anymore, at least if it is from a Mediterranean diet, latest research suggests.

A recent study published in the Lancet Diabetes & Endocrinology found that a calorie-rich Mediterranean diet consisting of "good" fats, such as those in olive oil, will not make you gain weight compared with a low-fat diet.

Researchers from the University of Barcelona studied the weight and waist measurements of 7,447 men and women in Spain who ate three different diets for five years.

One group was given Mediterranean diet rich in olive oil, the second had a similar unrestricted diet of nuts, and the third group kept to the conventional low-fat diet without any kind of fat.

Researchers found that while all three groups had lost weight, participants who had the olive oil-rich diet shed the most, with an average of 0.88 kg.

Those who belong to the low-fat group lost an average of 0.60 kg, and those from the nut-rich diet lost an average of 0.40 kg.

Researchers also found that waist circumference in the low-fat diet group increased by 1.2 cm compared with 0.85 cm and 0.37 cm in the olive oil and nut groups, respectively.

All participants had type 2 diabetes or were at risk of heart disease.

A Mediterranean diet is composed of vegetables and legumes, fruit, nuts, fish and whole grains, and the food is usually cooked with olive oil. Meat lovers who follow this diet also include poultry and lean meat, but avoid red meat, sugar and processed food.

"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," Dr. Ramon Estruch, lead author of the study, said in a statement published in the Daily Mail.

"Our findings certainly do not imply that unrestricted diets with high levels of unhealthy fats such as butter, processed meat, sweetened beverages, desserts or fast-foods are beneficial," he added.

In an editorial piece linked in the same edition of the Lancet, nutrition expert Professor Dariush Mozaffarian from Tufts University in Boston said that it was time to move away from the outdated guidelines on fat consumption.

"They don't have caveats with fruits and vegetables but do with fat. And this study shows we should get rid of that fear of fat," Mozaffarian told CNN.