He was born Francois Henri LaLanne in San Francisco, California, the son of French immigrants. At age 15, when he heard Paul Bragg give a talk on health and nutrition, LaLanne decided to focus on his diet and exercise habits. He studied Gray's Anatomy and concentrated on bodybuilding and weightlifting which, in the 1930s, was uncommon.

He originally planned to enter the field of medicine; but in 1936, he opened his own health spa in California and encouraged clients to better themselves through weight-training. He designed the first leg extension machines, pulley machines using cables, and weight selectors; equipment which is now standard in the fitness industry. In addition to designing various machines, LaLanne is credited as the inventor of the jumping jack. He was also the first to encourage women to weight-lift (at the time, people worried that this would make women look masculine and unattractive). By the 1980s there were more than 200 health clubs bearing his name (although he is no longer associated with any gym).

Between 1951 and 1984, LaLanne presented fitness and exercise advice on television. He has also published books and videos on fitness and nutrition, has appeared in films, recorded a song with Connie Haines, markets an electric juicer under his name, and used to market exercise equipment and a range of vitamin supplements.

His success as a body-builder became known worldwide, as well as his prodigious feats of strength. He has won numerous awards, including the Horatio Alger Association of Distinguished Americans and has a star on the Hollywood Walk of Fame. At age 91, he continues to work out every morning for two hours, one hour in the weight room and one hour in the pool. LaLanne and his wife of 50 years, Elaine (80) live in Morro Bay, California.

When interviewed by Katie Couric on NBC's Today show, LaLanne declared that his two simple rules of nutrition are: "If man made it, don't eat it; if it tastes good, spit it out." He often says, "I can not afford to die, it will ruin my image."