It appears that it may take as little as eating one meal that is high in saturated fat for it to have an affect on your arteries and good (HDL) cholesterol levels. Additionally, it can happen in a matter of hours.

In a two-year-old study, published in the Journal of the American College of Cardiology , 14 adults were given a piece of carrot cake and a milkshake that had been switched with one that contained either saturated (bad) or polyunsaturated (good) fat. While this may seem like some bizarre set-up for a Folgers commercial, it actually returned some interesting results with respect to how fast and how dramatically these fats can affect your health.

As it turns out, in merely three hours, participants that consumed the shake containing saturated fat had significantly narrowed large blood vessels. Three hours after that, the benefits of good (HDL) cholesterol showed a marked decrease in these same individuals. Those individuals who consumed the polyunsaturated (good) fat did not exhibit any signs of such physical detriment.