Born in September 1964, Phillips was raised in Golden, Colorado, where he lived with his father Bill (often referred to as BP), mother Suzanne, sister Shelly and brother Shawn. His father, William Phillips Sr., worked for the Coors Brewing Company while taking law classes at night. He reached the level of corporate analyst at Coors, then quit to open his own law practice.

Phillips started bodybuilding in 1982, then moved to Southern California to train at Gold's Gym Venice beach (known as the Mecca of bodybuilding) in 1983, remaining until 1986, a period during which Phillips admits to steroid use, at different times cycling on Deca Durabolin, Andriol, Sustanon, and other drugs that helped him grow from 185 lbs. to 215 lbs. After not succeeding as a bodybuilder, the 21 year-old Phillips moved back to Colorado where he took classes at the University of Colorado at Denver, specifically the study of exercise physiology and sports nutrition - with an emphasis on steroid chemistry. He then began his publishing career.

On November 11, 2005, he married Amy Molen.

In 1985 Mile High Publishing began with a small newsletter teaching bodybuilders how to use anabolic steroids. The newsletter was written and printed in his mother's garage. Funded with $180 he and his brother had made from mowing lawns, its original name was The Anabolic Reference Update. In 1991, Phillips began working with doctors and research scientists to develop performance nutrition products that could help athletes get better muscle-building and fat-burning effects from their workouts.

Muscle Media 2000 ("MM2K")

In 1992, Phillips moved out of his mother's home and changed the publication's format and its name to Muscle Media 2000 (usually referred to as "MM2K"). The magazine used frank discussion of the underground aspects of bodybuilding such as the use of and even how-to smuggle steroids, and columns by writers such as The Steroid Guru Dan Duchaine, Editor-in-Chief TC Luoma, Charles Poliquin, Mike Mooney, and Michael Dullnig M.D. aka "Dr. X."

Muscle Media 2000 debuted in March 1992 and featured bodybuilder Lee Labrada on the cover.

MET-Rx

In MM2K Phillips highly endorsed MET-Rx (a meal replacement supplement), and this relationship with readers helped it become the highest selling bodybuilding supplement ever at that time. It was later revealed however, that Phillips and the creator of MET-Rx, Dr. A. Scott Connelly, were in fact business partners, and the endorsements clever marketing. This partnership also included bodybuilders Lee Labrada and Jeff Everson. It was around this time that Phillips began working with James Bradshaw (later of SoCal Supplements). Bradshaw was convicted of dispensing human and animal steroids without prescriptions in 1986. This eventually would lead to Bradshaw serving four years in a Louisiana prison, where he educated himself on marketing. According to former Muscle Media 2000 editor-in-chief TC Luoma, it was Bradshaw who convinced Phillips to market MET-Rx heavily in the Natural Supplement Review, Phillips' supposed unbiased review of numerous bodybuilding supplements.He also had the idea for Phillips to give the Review away for free to readers of Muscle Media 2000 providing the MET-Rx with addresses of potential buyers, and a large amount of advertising. Sales of MET-Rx rose exponentially. Bradshaw and Phillips had stumbled upon a very successful method of marketing to bodybuilders, and they, and original investors Everson and Connelly, got very wealthy. Their partnership was short-lived however.

Phillips and Connelly had an agreement that distribution of MET-Rx would be controlled, and that they would not sell it to retail outlets in order to keep supply low during the period of high demand created by the advertisements in Muscle Media 2000. Connelly however, had other ideas and began selling it to mainstream distributors and department stores. Phillips believed this move lessened its appeal to bodybuilders, and destroyed the "mystique" of the product. The two parted ways, and as part of the settlement, Phillips was legally bound not to mention the name of MET-Rx in his magazines (thereafter he would refer to it as "the leading brand"). But by then Phillips had his eye on another venture that would eclipse MET-Rx altogether - EAS.

EAS

Phillips acquired Experimental and Applied Sciences (EAS) from founders Anthony Almada and Ed Byrd in 1996. He promoted the company's products through heavy editorial-style advertisements in MM2K, and led by flagship products like Myoplex (a meal replacement powder), the creatine supplement Phosphagen, and HMB this would eventually put him at the forefront of the nutritional supplement industry for more than five years.

By 1995 Phillips was a multi-millionaire, and was well known in celebrity and sports circles. Athletes like José Canseco would contact Phillips for advice on steroids, and he also consulted with celebrities such as Jerry Seinfeld, John Elway, Sylvester Stallone and Demi Moore.

In 1999 North Castle Partners purchased EAS for $160 million. Phillips retained about a third of the company, which he sold in 2004.

Muscle Media

In 1997 Phillips was eager to expand his empire beyond the bodybuilding industry. MM2K changed from targeting the hardcore bodybuilder to the more mainstream exercise participant, and the July 1997 issue saw the magazine redubbed simply as Muscle Media. While Muscle Media 2000 at its peak had a distribution of 500,000 copies per issue, the change in direction alienated many traditional readers, and sales numbers reportedly declined sharply afterwards. Publication finally ceased in 2004 after the EAS company was sold a second time.

High Point Media

In 1999, Phillips sold his majority interest in EAS (though he remained on the Board of Directors for a number of years afterward) to North Castle Partners for 160 million dollars and concentrated on his writing and on promotion of his books through his publishing company, High Point Media, as well as Value Creation, a branch of EAS. In 2004, he completely sold his remaining interest and is no longer involved with EAS.

Body-for-Life hit bookstores in 1999 and by 2003 it had sold 3.5 million copies in 24 languages. The book topped the charts in 11 different countries-including the United States, England, Japan, Australia, Greece and Finland. In 2004 USA Today named it among the Top 15 bestselling books of the past decade.

In November 2003, Eating for Life: Your Guide to Great Health, Fat Loss and Increased Energy! was released. In the book Phillips offers his plan "to help inspire and guide even more people to improve their health and lift their quality of life to new heights."

In February 2006 Phillips announced his "Great American Transformation Experience" (GATE) with a goal to transform America's fitness from world's worst to first within 10 years.

On June 21, 2010, Phillips' latest book, Transformation: The Mindset You Need. The Body You Want. The Life You Deserve was released. A companion website, Transformation.com, that walks individuals through the transformation process was also updated. The site features a community dedicated to supporting its members' personal goals. On July 10, 2010, the book made the New York Times Best Seller list.

Phillips has been honored by Paul Newman and by John F. Kennedy Jr. as one of America's most generous business leaders when EAS was honored in 1999 with a Newman's Own/George Award. The United States Junior Chamber of Commerce honored Phillips in January 2000 as one of the Ten Outstanding Young Americans. Phillips was also chosen to help carry the Olympic torch on its relay across the United States for the 2002 Winter Olympics in Salt Lake City. He has also donated $2 million to the Make-A-Wish Foundation.