That does not appear to be true. For instance, here is Walter Willett, chair of the department of nutrition at Harvard School of Public Health:

From many kinds of studies conducted over years, we are quite confident now that a calorie from fat will cause a similar amount of weight gain as a calorie from carbohydrate. There are some interesting questions about whether eating carbohydrate calories versus fat calories will make you eat more calories, but based on what you put into your mouth, it's pretty clear that the source of the calories is really not important.

http://www.time.com/time/health/article/0,8599,1822118,00.ht...