Created by fitness professional Tony Horton, P90X is a 12 DVD exercise program drawing from multiple disciplines to burn fat, build strength and increase flexibility. Along with the DVDs, the program includes a nutritional plan, workout schedule and online support. P90X isn't a weight-loss program as much as it is a fitness program; nevertheless, the rigorous workouts are effective at burning fat.
How soon you'll lose weight — or if you lose any at all — depends on a number of factors, including your commitment to the program, how drastic the changes are for you and how much weight you need to lose.
Science of Weight Loss
You lose weight by creating a calorie deficit, which can be done by eating fewer calories, burning more calories or combining the two strategies. To lose 1 pound of fat, you must accumulate a deficit of 3,500 calories. If you eat 250 fewer calories and burn an additional 250 calories a day you can lose 1 pound in a week.
A healthy, sustainable rate of loss is no more than 1 to 2 pounds a week, although if you have a significant amount of excess weight, you might see greater results initially.
Burn Fat with P90X
P90X doesn't provide information on the calories you burn during each of its exercise programs. However, by learning calorie burn counts for similar exercises, you can get a general idea of how many calories you use during their workouts.
According to the Harvard Medical School's Health Publication, which gives calorie counts for performing 30 minutes of various activities, a 155-pound person burns 233 calories performing vigorous weightlifting. Most P90X workouts are one hour, so you can expect to burn approximately 466 calories with the weight training DVDs.
Vigorous calisthenics burn 298 calories every 30 minutes or 596 an hour and kickboxing burns 372 calories every 30 minutes or 744 per hour, for a person of 155 pounds. Your calorie burn does depend on how much you weigh — the more you weigh the more you burn — and the intensity of your workout.
Following the P90X Classic schedule which has three weight training, one calisthenic, one kickboxing and one yoga workout during the first week, you would burn approximately 2,666 calories. So, using the P90X exercise program without changing your diet would result in a 1-pound weight loss every 10 days.
P90X Nutritional Plan
The P90X nutritional plan isn't a weight-loss diet. Instead, it's an eating program designed to fuel the body through the vigorous P90X workouts. The nutrition guide provides instructions on determining the number of calories you should eat to maintain your health while still burning fat. The plan has three phases for each 30-day segment of the 90-day program: Phase 1 Fat Shredder; Phase 2 Energy Booster; and Phase 3 Endurance Maximizer.
The difference between your current calorie consumption and the P90X nutrition plan determines how much and how quickly you'll lose weight. If your calorie consumption decreases by 500 calories a day while following the P90X plan, you can lose 1 pound per week.
P90X Exercise and Nutrition Plan
The fastest way to speed up fat loss is to combine a healthy diet and exercise. Following the P90X exercise and nutrition plan, you can create a calorie deficit of 6,166, which will result in a 1-pound weight loss every five days for a total of 18 pounds during the 90-day program.
These numbers are estimates of course. Other factors can impact weight loss, including lifestyle, muscle growth and body composition fluctuations such as water retention. P90X suggests taking body measurements and fat percentage along with weight to get a more accurate representation of fat loss. You may actually lose fat while on the plan, but gain muscle. This may not change the gross number on the scale, but you'll end up looking leaner and more fit.