Over 20 years, monkeys whose diets were not restricted were nearly three times more likely to have died than those whose calories were counted.
Writing in Science, the US researchers hailed the "major effect" of the diet.
It involved reducing calorie intake by 30% while maintaining nutrition and appeared to impact upon many forms of age-related disease seen in monkeys, including cancer, diabetes, cardiovascular disease and brain atrophy.
Whether the same effects would be seen in humans is unclear, although anecdotal evidence so far suggests people on a long-term calorie-restricted diet have better cardiovascular health.
"People would have to weigh up whether they are prepared to compromise their enjoyment of food for the uncertain promise of a longer life, and a life which could be dogged by all sorts of problems - including osteoporosis."