P90X is an advanced fitness training program developed by the Beach Body Company, which is behind the development of the Power 90 series of nutrition products. The fitness program incorporates a detailed three-phase nutrition plan that includes special diet regimes, fitness guide, specially customized supplements, and a calendar to monitor progress. The system is built around 12 highly intense muscle-building training programs that shape the body within a span of 90 days.

The P90X system depends on the advanced training technique known as 'Muscle Confusion'. This technique leads to the development of newer muscle mass by repeatedly changing the routine of physical training moves and exercises. The fitness training system is presented by personal trainer Tony Horton, with numerous methods of exercise routines. The innovative fitness routines developed by Tony are based on years of clinical research and personal experience.

Nutritional specialist, educator, author and chef, Carrie Wiatt, helps achieve the perfect balance between exercise and diet with her specially customized nutrition plan. The plan enlightens one about the daily intake of nutritive elements to keep up with the vigorous work-out routine. The nutrition program is based on 20 years of experience and research undertaken by Carrie herself. The program is customized to suit individual needs and habits of eating, daily activity, and the suggested exercise regime. The entire program helps an individual lean up, bulk up, and shape up to the desired physique.