Along with the intense workouts included in the P90X program is a three-phase nutrition plan that encourages you to use P90X-brand protein bars as snacks. A box of 12 bars costs about $24, and they come in flavors such as chocolate fudge and wild berry. If you've run out of the bars, aren't partial to their taste or prefer whole foods, you can still follow the meal plan without derailing your results.

The P90X bars contain 20 grams of protein, 250 to 270 calories and 30 to 40 grams of carbohydrates. They are usually included as a morning snack, along with a P90X brand recovery drink, consumed just after your workout. The high-protein nature of the bar is important to the first two phases of the nutrition plan, which seeks to increase your protein intake to help you cut fat and boost energy.

While Beach Body, the parent company that produces P90X and the supplemental products, claims that the bars contain an important combination of vitamins and minerals necessary to support a person going through the program, you could substitute with a similar protein bar without becoming nutritionally deficient. P90X bars contain no trans fats or high-fructose corn syrup -- so look for bars with a similar makeup. Make sure any bar you choose also provides the 20 grams of protein and a similar number of carbohydrates and calories.

The nutrition program lists a number of snacks, of which the bars are just one option. Alternative snacks include 12 ounces of low-fat cottage cheese, 1 ounce of nuts, 4 ounces of soy nuts, 3 ounces of string cheese and 2 ounces of turkey jerky. If your meal plan calls for just 1/2 of a bar as a snack, suitable alternatives may be 1 tablespoon of peanut butter spread on celery sticks, 12 mini rice cakes, 1 ounce of dried fruit or 8 ounces of plain, nonfat yogurt.

The P90X nutrition plan notes that you may need more calories than you initially calculate. Running out of energy during workouts is a telltale sign that you're not eating enough and could use an extra protein bar daily. Another way to add extra calories without using a protein bar is to add a meal instead of a snack or have a handful of nuts or dried fruit.