Fat is your friend. Going against the standard diet-book philosophy, Dr. Lyons advises readers to embrace their fat intake as long as it's the right kind of fat. People need to trim their unhealthy, gut-forming yellow fat and replace it with so-called brown fat and sugar-burning tissue, which was only recently confirmed to exist in adults. This is done by avoiding food that leads to yellow fat, particularly most processed foods, and indulging in food that promotes brown fat, such as avocados, nuts and salmon. By doing this in combination with an exercise routine that's focused on building lean muscle (as opposed to cardio), Dr. Lyons hopes that you too will be singing fat's praises.