Swedish researchers discovered that people who eat a lot of polyunsaturated fat gain more muscle - and less fat - than those who eat a lot of saturated fat.People who eat mainly polyunsaturated fat - which salmon and walnuts are rich in - also store less fat around their waists and their internal organs.This was the first study on humans to show that the fat composition of food not only influences cholesterol levels in the blood and the risk of heart disease, but also where in the body fat will be stored.Researchers at Uppsala University studied 39 young adult men and women of normal weight, who ate 750 extra calories a day for seven weeks. The goal of the study was for them to gain three per cent of their starting weight during the seven weeks of the programme. Half of the participants were randomly selected to eat their surplus calories from polyunsaturated fat - sunflower oil.The rest got their extra calories from saturated fat - palm oil. Both diets contained the same amount of sugar, carbohydrates, fat, and protein - the only difference was the type of fat.The increase in body fat and the distribution of fat in the body was measured using MRI scans before and after the weight gain, as was the muscle mass in the body. Gene activity was measured in the abdominal fat before and after the weight gain with the help of a gene chip that studies several thousand genes at a time.The researchers found that there were similar weight gains between the two diet groups.However, they also noted that the people who ate more saturated fat stored more in their liver and abdomen.The total amount of body fat stored was also greater in the saturated fat group.This group was also found to gain three times less muscle than the group who got their extra calories from polyunsaturated fat.The researchers believe their findings also suggest people who eat lots of polyunsaturated fat are less likely to develop heart disease and diabetes.‘Liver fat and visceral fat seems to contribute to a number of disturbances in metabolism. ‘These findings can therefore be important for individuals with metabolic diseases such as diabetes. ‘If the results regarding increased muscle mass following consumption of polyunsaturated fat can be confirmed in our coming studies, it will potentially be interesting for many elderly people, for whom maintaining muscle mass is of great importance in preventing morbidity,’ said Ulf Risérus, associate professor at the Department of Public Health and Caring Science and director of the study.Storing fat around the organs is associated with increased risk of type 2 diabetes and cardiovascular disease.A number of previous studies have indicated that a higher intake of polyunsaturated fats from plant oils and nuts is associated with a decreased risk of type 2 diabetes, but the reasons for this remained unclear.The present study proposes a potential explanation for such an association, showing that polyunsaturated fatty acids can affect fat distribution in the body more favourably than saturated fats.The researchers were also able to see that overconsumption of saturated fats seems to be able to ‘turn on’ certain genes in fatty tissue that increase the storage of fat in the abdomen and at the same time hamper insulin regulation. Polyunsaturated fats, instead, can ‘turn on’ genes in visceral fat – the fat stored around the vital organs - that in turn are linked to reduced storage of fat and improved sugar metabolism in the body.Saturated fat is found in butter, cake, biscuits, fatty cuts of meat, cheese and cream.Unsaturated fats are found in oily fish, nuts and seeds and olive oil.(dailymail.co.uk)ANN.Az