We've long known that unsaturated fats are better for us than the saturated kind. The former still pack a hefty caloric punch, but they can actually help lower the risk of heart disease and type 2 diabetes, whereas the latter raise LDL levels and cardiovascular risk. A new study shows one reason that may be: People who eat more saturated fat gain fat around their middle, whereas people who eat more unsaturated fat gain relatively more muscle and less fat overall – and less abdominal fat in particular.
Researchers fed about 40 normal weight young people a muffin everyday for seven weeks. Thanks to that muffin, each person was eating an extra 750 calories or so a day. Half the people ate muffins made with sunflower oil, a polyunsaturated fat, and the other half ate muffins made with palm oil, a saturated fat. After seven weeks, people in both groups had gained weight (a good reminder not to hit the bakery on the way to work every morning), and similar amounts of it.
The people who'd eaten muffins made with saturated fat carried the weight primarily as fat, especially in their abdomen and around their liver and other internal organs – something that can upset metabolism and contribute to diabetes and heart disease. But the folks who ate unsaturated fat-based muffins gained more muscle mass and less fat, without the same marked increase visceral fat, a much healthier – and, yes, sleeker – way to carry their extra pounds.