You need an accurate assessment of your body composition. Have your body fat percentage measured at a health club, a local university (by the exercise physiology department), or a local hospital. You should aim for a body fat percentage between 2-4% by contest time; so you must determine how much fat you have to lose. For example, a bodybuilder weighs 200 pounds with 10% body fat, so he has 20 pounds of fat (200 x .10). To get down to 2% body fat, he would need to lose 16 pounds of fat.

You must have a basic understanding of nutrition. Here is a quick run down of the most important things you need to know in order to make a pre contest diet. A pre contest diet is very restrictive and potentially unhealthy. Therefore, the diet should be done in the shortest time possible. In fact, your off season body fat should not exceed 8-10%. If your body fat is within this range it should take 12-16 weeks to get it down to 2-4% body fat, which is usually the body fat of a bodybuilder on the day of the contest.

• There are 9 calories per gram of fat, 4 calories per gram of protein and 4 calories per gram of carbohydrate;
• Complex carbohydrates should be the only carbohydrates eaten; except after a work-out when simple sugars can be eaten (a list below will show the best carbohydrate sources);
• Only extra lean sources of protein are to be eaten (a list below will show the best protein sources);
• A moderate consumption of fiber should be eaten at each meal;
• All grams should be counted for each meal to keep you on the right rack.

• Convert your weight from pounds to kilograms. Take your weight in pounds and divide it by 2.2. For example: 190 lb / 2.2 = 86.3 kg;
• Convert your height from inches to centimeters. Take your height in inches and multiply it by 2.54. For example: 67 in. x 2.54 = 170.1 cm.

• Males:
  66 + [13.7 x (weight in kg)] + [5.0 x (height in cm)] - [6.8 x (age in yrs)] = BEE (in calories);
• Females:
  655 + [9.6 x (weight in kg)] + [1.8 x (height in cm)] - [4.7 x (age in yrs)] = BEE (in calories);

We now have to figure out how many grams of protein, carbohydrate, and fat to eat in each meal by dividing the calories among the macro nutrients, i.e. protein, carbohydrates, and fats. The following distribution is for pre contest dieting only. These percentages should not be followed for more than 16 weeks at a time:
 

Let us assume that the person dieting needs 216 calories per meal, 40% protein, 50% carbohydrate, and 10% fat. The following formulas would be used:
 

Now you know the exact number of grams of protein, carbohydrates, and fat that should be eaten at each meal.

Okay, now you know the grams for each macronutrient for each meal, but you need to know what the best foods are for losing body fat.  Listed below are the best sources of each macronutrient excluding fat because it is in lean meats and protein powders you are eating.

Combine any three, one from each column, and you have a pre-contest meal.  Portion size will depend on the amount of grams you are permitted at each meal.

• Fiber aids to slow down the digestion of carbohydrates which has a direct effect on insulin.  A bodybuilder wants stable insulin levels as insulin spiking can cause the deposition of fat into adipose (fatty) tissue;
• Fiber from vegetables releases medium chain triglycerides in the intestines which act as a good source of fuel without the worry of fat deposition.  This is especially good when carbohydrate and fat levels are extremely low;
• The kind of fiber I recommend is from cruciferous vegetables (broccoli, kale, spinach, cauliflower, bell peppers, and green leafy vegetables) which are nutrient dense with little to no calories;
• Last but not least, fiber prevents constipation.

It is very important to monitor your progress accurately. Track your weight with a scale, your measurements with a tape measure, and your body fat percentage with skinfold calipers or another accurate body-fat measure.  Of course the most accurate measure is the mirror.  If you are looking defined you will know it. However, always get another critical opinion that will tell you the truth regardless of how cruel it is… for me it is my brother.

Even if you are doing everything right, your body doesn't always respond like you want it to.  This is the purpose for continually monitoring your progress.  If you are not losing body-fat as quickly as you'd like add aerobic exercise to your routine doing 20 minutes per workout separate from your weight training.  Initially do the aerobic exercise 2-3 times per week; if your body-fat still has not decreased increase the aerobics to 4-5 times per week.  As a natural bodybuilder your body is prone to catabolism which can result from extended aerobic work-outs and lead to loss of hard earned muscle.

On the other hand, you may lose weight too rapidly which can accompany muscle loss.  In this case you would slightly increase your protein and carbohydrate intake.  Any alterations should be done in small increments and recorded carefully.

Every pre-contest diet is a learning experience.  In order to learn from each experience you must accurately record every detail; what you eat, how you train, your body weight, your body composition, your measurements, and how you feel.

If this process seems a little complex, it is!  Dieting is a science and each body has slightly different laws by which they function.  However, we are all alike in how we gain and lose body-fat.  It is merely a question of how much or how little we need to obtain the desired result.