Simply A few points:
1. There’s no such thing as a “low fat diet.” They’re all high fat diets if fat loss is the goal. 2. The lowest carbohydrate intake of all the diets was a whopping (yea, I can do the media hype, too) 35%. Presuming an average 2,500 kcal intake per day, that’s about 220 grams of carbs — not “low carb” by any means. So, this is merely a comparison between various moderate to high carb approaches — approaches that leave insulin high and fat mobilization low. 3. The highest fat intake is only 40%. A true high fat diet is 60%+ of energy from fat. You can’t go above about 35% from protein, and that’s pushing it (25% is more realistic). Simple: protein remains about the same, and the tradeoff is between carbs and fat. This study was heavily weighted in favor of carbs, particularly when one considers that carbs hammer insulin and fat has little to no effect. High insulin = no fat mobilization. In conclusion, they proved that all diets with excess carbohydrate are crap and deliver virtually no results for most people.
In “The Latest Nonsense” (at Free The Animal) Richard Nikoley makes some good comments about the NIH study: