A new study by Swedish researchers has found the composition of food influences where in the body fat will be stored
The researchers, from Uppsala University, studied 39 young adult men and women of normal weight who ate 750 extra calories a day for seven weeks.
Half of the participants were asked to get their surplus calories from polyunsaturated fat while the other half got theirs from saturated fat. Both groups were asked to consume the same amount of sugar, carbohydrates, fat and protein, with the only difference being the type of fat they had.
Any increase in body fat, the distribution of that fat in the body and muscle mass was measured using MRI scans before and after the experiment. Gene activity was also measured in the abdominal fat before and after weight gain.
The study found that people who eat a lot of polyunsaturated fat (found in salmon, olives, olive oil and nuts) gain more muscle (and less fat) than those people who eat a lot of saturated fat. They also found that people who eat mainly polyunsaturated fat store less fat around their waists and internal organs.
During the experiment both groups experienced a similar amount of weight gain, but people in the saturated fat group stored more in their liver and abdomen. The total amount of body fat stored was also greater in this group and they gained three times less muscle than the group who got their extra calories from polyunsaturated fat.
Researchers believe their findings may also suggest that people who eat lots of polyunsaturated fat are less likely to develop heart disease and type 2 diabetes, as storing fat around the organs is associated with increased risk of these conditions.
The study concluded that eating too much saturated fat seems to turn on certain genes in fatty tissue that increase the storage of fat in the abdomen, while eating a lot of polyunsaturated fat can instead turn on genes in visceral fat (fat stored around the vital organs) that are linked to reduced storage of fat and improved sugar metabolism in the body.
Butter, cake, biscuits, cheese, cream and fatty cuts of meat are all high in saturated fat.
Unsaturated fats are found in oily fish, avocado, nuts, seeds, olives and olive oil.
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