The controversy is over. Consuming fewer calories leads to a longer, healthier life, according to a joint report from the Wisconsin National Primate Research Center and the National Institute of Aging (NIA) on the diets of rhesus monkeys.

This report is the third in a series researching the effect of caloric intake on aging. In 2009, the UW–Madison team, led by primate center scientist Dr. Ricki Colman, reported that rhesus monkeys that ate less had fewer instances of cancer, cardiovascular disease, and insulin resistance. However, a 2012 study from the NIA showed no significant correlation between diet and health. With both teams hungry for an answer, they worked together to reach a more satisfying conclusion.

“These conflicting outcomes had cast a shadow of doubt on the translatability of the calorie restriction paradigm to understand aging and what creates age-related disease vulnerability,” said Rozalyn Anderson, an associate professor of medicine at UW–Madison collaborating with Dr. Colman and others on the study.

After comparing the two independent reports, the research team drew four key conclusions.

• Eating less is more beneficial for adult and older primates than for younger or juvenile animals.
• The number of calories reduced matters. The test group at UW–Madison ate less than the group at NIA and was less at risk for major health issues.
• Less processed food leads to fewer health issues. The NIA primates ate naturally sourced foods compared to the high-fat, sugar-rich diet of those at UW – Madison.
• Comparatively, females are less affected by a fatty diet.

While the two original studies considered caloric intake, they didn’t factor in the effect of age, diet, and sex. It’s those other ingredients, when evaluated alongside calorie count, that make up the complete recipe for healthy living. Energized by this discovery, researchers continue to explore the interaction between calorie count and quality of life.

Reviewed August 2019

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Photo credit: Yerkes National Primate Research Center