Lean Diet: Get Lean and Clean with Delicious Lean Recipes The Lean Diet book has recipes that support the lean diet. The lean diet is a diet in which is low in fat and low in unhealthy carbs. The idea behind the lean diet is to help aid the body to a more ideal weight level. Weight issues cause so many problems with heath. Dieting is the best way to both lose weight and maintain a good weight level. The foods included in a lean diet are foods that help the body to lose excessive weight and fat and help the body to stay within a good weight range, but it is a lifestyle change.