From Nature:
Eating some fats could make you fatter than others, even if their calorie count is the same.
That’s the finding from researchers who fed trans-fatty acids, commonly found in fast food, to monkeys. Those that ate a daily dose of the trans-fatty acids gained 30% more lard around their bellies than those who ate different fats containing exactly the same amount of calories.‘Trans-fats’ are already considered to be a dietary villain because they boost levels of ‘bad’ cholesterol and promote heart disease. But when it comes to obesity, it is generally assumed that trans, saturated and unsaturated fats are equally problematic, because they are loaded with the same amount of energy. This study says otherwise. It suggests that trans-fats could promote obesity more than other types of fat. People who eat them could be “walking down the road to disaster”, says lead author Kylie Kavanagh at Wake Forest University Baptist Medical Center in Winston-Salem, North Carolina.
More here.