5 Factor World Diet. I love the approach to this “diet” book. Famous nutritionist and trainer Harley Pasternak studied populations all over the world with the lowest incidence of obesity and took note of what they ate. His 5-Factor diet ($16) is super basic and easy to follow: five meals a day to elevate metabolism and decrease body fat; five specific nutrients for each meal (protein, carbohydrates, fiber, healthy fat, and water or tea) to burn fat and boost your metabolism. (via FitSugar)