Even though this study used grain-fed meats, it proves that even a little of the low-grain approach works best.  The Atkins Diet doesn't emphasize grass-fed meats.  If it had, the meat eaters in this study would have lost considerably more weight.  But just the same, this study provides some guidance about how one should eat.  The link takes you to an article summarizing the research.  In that research you'll see that the low-fat, restricted-calorie diet based on the American Heart Association's guidelines was worse than the Mediterranean Diet.  The Mediterranean Diet came in second to the Atkins Diet.  All this strongly suggests that "The Diet of Man" is the one and only diet of man.  It also suggests that the dietary information of the American Heart Association is merely the status quo of the failed science of 50 years ago.  The title of this release is Low-fat Diet May Not be Best Choice.