Jack LaLanne's Advice Stood Test of Time, Unlike Contemporaries Fixx and Montignac

Jack LaLanne, an exercise guru whose advice stood the test of time, died Sunday at age 96. LaLanne, famous for his television exercise programs, was nicknamed the godfather of fitness.

LaLanne's "firsts" include first health club opened in the United States and first exercise television show. Decades before the health club craze went mainstream, LaLanne opened in Oakland, Calif.-the year was 1936. In some quarters, he was considered a health nut to be avoided in those days.

"The Jack LaLanne Show" ran for 30 years, beginning in 1951. I remember watching the show as a kid in the 1960s. I specifically remember LaLanne's touting exercise as the key to a long life. As a child, I remember wondering how long LaLanne would live, thinking that would be an indication of the validity of his advice. While LaLanne's 96 years aren't a guarantee that others following his advice will become nonagenarians, his long, healthy life does give some credence to his emphasis on exercise and nutrition as elements of longevity.

There have been other diet or exercise gurus professing to know the secrets to longevity whose advice did not stand the test of time. One notorious example is the runner Jim Fixx. Fixx wrote The Complete Book of Running in 1977. His book sped to the top of the New York Times bestsellers list and remained there for nearly two years.

Fixx posited that running was the key to health and longevity and developed a following. In particular, Fixx advocated running as a means of warding off cardiac disease. The running craze gained momentum, and Fixx's book was a bible to many. Then, in 1984, Fixx suddenly died on the side of a road where he'd been running. He was but 52 years old. The cause of his death was a heart attack.

Michel Montignac, author of Dine Out and Lost Weight and Eat Yourself Slim...and Stay Slim!, similarly rose to fame by giving out life-extending advice. His diet, he said, would not only promote weight loss but "prevent illness and disease," particularly heart disease and diabetes. He contended that traditional weight loss advice calling for eating less and exercising was dangerous and actually promoted obesity.

Montignac's advice was rejected by mainstream dieticians. Montignac died at age 66. The effectiveness of his dietary advice remains controversial. Since he died of prostate cancer , his death at a relatively young age is less likely to affect his followers' views of the validity of his diet program.