Interesterified fats are not trans fats. However, they were developed to take the place of trans-fats in commercially produced baked goods and snack foods. Interesterified fats have been chemically or enzymatically altered to improve their texture or nutritional profile. They're produced by combining stearic acid, found in chocolate and considered a relatively safe saturated fat, with vegetable oils containing unsaturated fat.
We really don't know much about these new fats yet, and their short and long term consequence on health have not been well researched. However, a study published in the January 15, 2007, issue of Nutrition Metabolism found that interesterified fats and trans fats had similar, negative effects. Both increased total cholesterol, raised "bad" LDL (low density lipoprotein) cholesterol and lowered "good" HDL (high-density lipoprotein) cholesterol. Another negative: the interesterified fat also raised fasting blood glucose by almost 20 percent. Because the study was small - only 30 individuals participated - the American Heart Association took the position that the "safety profile of interesterified oils and shortenings isn't as well understood as that of natural fats and oils" and that more research is needed. Since this is an unsettled issue and because there's some reason to believe that these fats may have negative health effects, I would recommend staying away from products containing interesterified fats until we know more.
Why can't these corporations just provide healthy foods instead of wasting their money trying to create new ways to kill us.
Very good question.