Good nutrition can be defined as a healthy way of eating that supports your life goals. Regular exercise cannot compensate for improper nutrition. To get the most from your training program you have to pay the same amount of attention to your diet as to all the other aspects of the program. If weight loss is one of your goals, then a long-term change of eating habits is much more beneficial than a short-term fad diet. Good nutrition is not a sacrifice but a choice and a matter of knowledge and common sense.
The food necessary for a regular healthy life style is not always the same as the food that supports your training program. What to eat and when is critical to the success of your work out program. Choices of the correct supplementation are also important. Artificial supplements (such as steroids) are never appropriate and may even be dangerous.