If you want to gain muscle mass, you must eat enough dietary fat. Dietary fats play an essential role in hormone production, which in turn is responsible for growth and strength increases. I have never gained muscle on a low fat diet, though many people still believe that eating fat makes you fat. This is absolutely false. In fact, there is a very popular muscle gain diet that been around for years, called the "Anabolic Diet" that requires you to eat only fat! Butter, bacon, and heavy cream are all on the menu. Though quite extreme, this diet does work.

Most people are overweight because of a diet high in simple carbohydrates, not from eating fats. If your diet is too low in fat, your body will actually make a point to store any fat it gets, because it doesn't know when it will get more. A low-fat diet will also lower testosterone levels, something we do not want when trying to gain weight. Studies have shown that dietary fat has a direct relationship with testosterone production. An increase in dietary fat intake seems to bring on an increase in testosterone levels. The inverse is also true. A decrease in dietary fat intake is usually accompanied by a decrease in free testosterone levels.

However, you don't want to increase your intake of saturated fats. Saturated fats are what cause disease and coronary problems. Though you will always have some saturated fats in your diet, your main focus should be to increase your intake of Essential Fatty Acids (EFAs).