College of Health Solutions professor’s work could have an impact on healthier aging

Could a reduction in calories be the key to a healthier — and possibly longer — life?

That’s a question a College of Health Solutions professor has been working on for more than 20 years. Susan Racette, who came to Arizona State University in the fall of 2022, is one of the authors of an article appearing in the Feb. 9 edition of Nature Aging regarding a study that has been looking at the impact of calorie restriction on aging.

The article, "Effect of long-term caloric restriction on DNA methylation measures of biological aging in healthy adults from the CALERIE trial," involves a long-term study that Racette has been involved with since the first phase of the research in 2001, when she was at Washington University School of Medicine.

CALERIE (Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy) was a multicenter trial that involved three clinical sites, including Washington University. Racette remains an investigator on the two current CALERIE grants, and her efforts have transferred to ASU.

“It’s exciting, partly because it’s so important,” Racette said. “If we can actually impact biological aging, that’s very important. It’s also novel. This is the first randomized control trial of calorie restriction in humans.”

The CALERIE trial was designed to study the effects of restricting calories by 25% for two years among healthy adults without obesity. The current CALERIE Legacy study is exploring whether participation in the CALERIE trial 10–15 years ago has had any long-term impacts on aging or aging biomarkers.

“It has been shown in many different animal models that calorie restriction not only prevents some of the age-related diseases — diabetes, hypertension, cancer — but it actually prolongs life,” Racette said. “It increases health span and life span.”

Though the participants in the study were not doing so with a goal of losing weight, Racette said some of the findings could be relevant to people who have undertaken calorie restriction with weight loss as a goal through practices such as intermittent fasting and time-restricted eating.

“This (the CALERIE trial participants) was a very select group of people who were already very healthy and motivated,” Racette said. “Now there are new strategies people can use to achieve calorie restriction that might be a little more agreeable or feasible for them. There are a lot of studies looking at intermittent fasting now that could be very relevant to this topic.”

Racette said the ultimate goal of the research is to look at ways to extend the number of healthy years people have.

“You can’t really prevent aging from happening, but can you slow the pace at which the cells and tissues age to increase health span?” she questioned. “The goal is to increase the number of years during which somebody is healthy. Whether or not it increases life span as it does in the animal models, we don’t know, but the more pressing goal is to increase health span.”