Eat Trans Fat, Get Big Belly

Trans fats make you fatter than other foods with the same number of calories -- but that's not all. Researchers at Wake Forest University find that trans fats increase the amount of fat around the belly. They do this not just by adding new fat, but also by moving fat from other areas to the belly.

"Trans fat is worse than anticipated," Wake Forest researcher Lawrence L. Rudel, PhD, says in a news release. "Diets rich in trans fat cause a redistribution of fat tissue into the abdomen and lead to a higher body weight even when the total dietary calories are controlled."

Rudel colleague Kylie Kavanagh, DVM, reported the findings at this week's annual meeting of the American Diabetes Association in Washington.

In the study, researchers fed 51 male vervet monkeys a western-style diet -- that is, 35% of their diet was fat. Half the monkeys got a lot of trans fat, totaling 8% of their diet. The other monkeys were fed unsaturated fats such as olive oil.

Both types of diets were calorie-controlled. In theory, the monkeys should not have gained weight.

But they did.

Over six years -- what would, in humans, be a 20-year span -- the monkeys who ate unsaturated fats upped their body weight by 1.8%.

Those fed trans fats packed on 7.2%. In humans, that would be enough weight gain to significantly increase risk of diabetes and heart disease.

"Trans fatty acid consumption increases weight gain," Kavanagh says in a news release. "In the world of diabetes, everybody knows that just 5% weight loss makes enormous difference. This little difference [of weight gain seen in the study] was biologically quite significant."

Trans fats are found in vegetable shortenings, some kinds of margarine, and in manufactured baked goods such as cookies, crackers, and snack foods. A major source of trans fat in American diets is fast food fried in the stuff.

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