Sporting performance comes from good physique. Everything in your body is created from blood, which is dependent on good nutrition. So what you eat directly affects your performance. It could result in a longer career, better performance and reduced chance of injury.
The diet is different mainly because it works without missing out food groups or starving yourself. It concentrates on the life force and energy that the food provides and not the amount of calories that it contains. Who would be healthier, someone who ate 2500kcal of salad a day or someone who ate 2500kcal of sweets, what I'm trying to say that nutrients count more than calories. The nutrients will make healthy blood, which will make you healthy.
Supplements are very important for improved health and performance. They will improve energy levels and health, help maintain ideal weight and improve speed of recovery.