I just finished reading Protein Power, and there's an excellent table in the book that shows how dietary fat has absolutely no impact on insulin levels. Insulin is what is behind making most of us fat. Too much of it is associated with bad cholesterol production, high blood pressure, triglycerides, diabetes, etc. Eating high fat foods--no matter how much--has no impact. But there IS a catch! As soon as carbs in sufficient numbers (such as in a "normal" diet) are added--(fat + carbohydrates), the insulin levels shoot way up. Most of the foods we all love(d) to eat are high fat+carbs (donuts, pies, cake/frosting, chips, etc. Even toast with butter, and our favorite combinations: sausage & hash browns, peanut butter & jelly sandwiches, meat & potatoes/gravy, etc. are high carbs/high fat.) This study your sister sent you only specified that last group as "high fat". Tell her that low carb+high fat is healthy, and back it up with the Harvard study, just published last week. The link is on this forum. I found it searching Yahoo-Health. The study followed obese women for 6 months (half were high carb/low fat, the others were low carb/high fat & protein. After 6 mo., the low carbers lost significantly more pounds, more body fat, and ALL subjects' blood cholesterol levels/lipids, etc. were in the normal range.