A long-running study suggests that one of the simplest ways to support healthy aging may also be one of the most effective: eating slightly fewer calories.
Search online, and you will find countless biohacking trends that promise healthier aging, from cold plunges and hyperbaric oxygen therapy to sleeping under red lights.
But research from Tufts University and other institutions points to a much simpler strategy that appears to work: eating slightly fewer calories. Studies suggest that reducing calorie intake by just 10% to 15% can lower the risk of age-related diseases by improving heart health, reducing blood pressure, and supporting better glucose control. For some people, the change could be as simple as skipping a large daily latte.
“It doesn’t have to be some extreme measure,” says Sai Krupa Das, a senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University. Das studies how nutrition and lifestyle habits influence healthspan, meaning the years people stay healthy as they age. “There are nutrition and lifestyle changes that can not only prevent chronic disease but also slow down the rate of aging.”
CALERIE™ Study Reveals Lasting Health Benefits
The findings come from CALERIE™, short for The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy. Researchers at Tufts and collaborating institutions have been studying the effects of calorie restriction for nearly 20 years. The first phase ended in 2011, but scientists are still analyzing and publishing results from the large amount of data collected.
In the initial phase of the study, 143 participants tried to reduce their calorie intake by 25% for two years, while 75 others continued eating normally as the control group. Throughout the study, participants regularly visited one of three research centers, HNRCA, Washington University, or Louisiana State University, for extensive testing that measured factors including weight, blood pressure, and glucose tolerance.
Participants needed what Das described as “a wonderful mindset.” When enrolling, they did not know whether they would join the calorie restriction group or the control group. Volunteers had to be prepared to make major lifestyle changes while also accepting the possibility that they might not need to change anything at all. “They had to be very good scientific citizens, and they were,” Das says.
Moderate Caloric Restriction Improved Blood Pressure and Cholesterol
The two-year intervention ended in 2011, and researchers found notable improvements among participants who reduced calories. Many shifted their diets away from fats and toward more protein and carbohydrates. Although the group achieved only about a 12% calorie reduction instead of the targeted 25%, they still experienced significant declines in blood pressure, LDL-C (“bad”) cholesterol, and insulin levels compared with the control group. Participants also lost about 10% of their body weight, even though weight loss was not the study’s main goal.
“The most exciting part is that we saw these benefits with only a moderate level of restriction that’s feasible for most people,” Das says. “And that was in a healthy population without obesity. When we apply this to people with overweight or obesity, we expect the outcome to only get better.”
Researchers continue to publish new analyses from the study. A paper released earlier this year found that lowering calorie intake did not reduce the overall nutritional quality of participants’ diets. Although participants in the restricted group took multivitamins and calcium supplements, food records suggested they likely would have maintained adequate nutrition even without them.
How Eating Less May Reduce Cellular Damage
Scientists are still working to understand exactly why calorie restriction improves health. One theory is that eating less helps the body generate energy more efficiently while producing fewer reactive oxygen species, unstable molecules that can damage cells and contribute to diseases ranging from cancer to Parkinson’s disease. Urine testing confirmed that participants in the calorie restriction group had lower levels of these molecules than the control group.
The CALERIE™ project is still ongoing. Researchers recently invited participants back for follow-up testing to determine whether the lifestyle changes made during the study continue to affect their health more than a decade later. Surveys will also examine whether participants maintained lower calorie intake after the formal study ended. Das and her colleagues have completed data collection and are now analyzing the results.
“I think the follow-up was necessary simply because we found such wonderful results in the primary study, and it is important to understand what the longer-term impacts are,” she says.
Easy Ways to Cut Calories Without Extreme Dieting
Das says many healthy adults can safely try moderate calorie restriction without participating in a clinical study. However, some groups should speak with a doctor before reducing calories, including adults older than 65, children, pregnant people, individuals with a body mass index below 22, and anyone with bone density loss or medical conditions that require medication.
“There are online tools that you can use to calculate how many calories you’re currently eating per day. Use that, and then take off 20%, or even just 10%,” she says.
A large chocolate chip cookie can contain around 200 calories, so someone eating a 2,000-calorie diet could reduce intake by 10% simply by skipping a daily dessert. Sugary coffee drinks can also add more calories than many people realize, making them another easy target for small reductions.
People can also spread calorie cuts throughout the week in ways that suit their lifestyles. Some prefer limiting calories on only two days per week, an approach known as 5:2 intermittent fasting.
Even Small Calorie Cuts Can Extend Healthspan
Researchers still do not know whether calorie restriction works best as a permanent lifestyle or as a shorter-term intervention like the CALERIE™ study. Das recommends paying attention to how your body responds. Feeling underweight, lightheaded, or low on energy may signal that adjustments are needed.
“You don’t have to shoot for crazy numbers, like 30% or 40% restriction. Even 10% is very helpful,” Das says.
She adds that these benefits may become even more important as medical advances help people live longer. Extra years matter most when they are spent in good health.
Reference: “Diet quality and nutritional adequacy during a 2-year calorie restriction intervention: the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy 2 trial” by Susan B Racette, Rachel E Silver, Valene Garr Barry, Jasmyn J DeGraff, Jordan A Gunning, Maryam Kebbe, Cheryl H Gilhooly and Sai Krupa Das, 29 December 2025, The American Journal of Clinical Nutrition.
DOI: 10.1016/j.ajcnut.2025.101182
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