Restricting Calories Could Help You Live Longer

by: Donna Bell

Could a Calorie-Restricted Diet Slow Aging? 

By Donna Bell

Edited and Approved by Stephen C. Rose, PhD

Calorie restriction has fascinated aging researchers for decades. In animals, reducing calorie intake without causing malnutrition can extend lifespan in many species. In humans, the evidence is more modest but still interesting: the best clinical studies suggest that moderate calorie restriction can improve several cardiometabolic risk factors and may slightly slow some measures of biological aging. What has not yet been proven is that calorie restriction definitely extends lifespan.[1–5]

What is calorie restriction?

Calorie restriction means eating fewer calories than usual while still meeting the body’s needs for protein, essential fats, vitamins, minerals, and other nutrients. That distinction matters. Calorie restriction is not starvation, crash dieting, or simply eating as little as possible. The goal is to reduce energy intake without creating malnutrition.[1,2,6]

That is also why calorie restriction should be approached carefully. The right calorie target depends on age, body size, sex, activity level, health status, medications, and personal goals. A sustainable plan usually works better than a dramatic cut that is hard to follow and risks nutrient shortfalls or excessive lean-mass loss.[1,6,7]

What does the human evidence actually show?

The strongest human data come from the CALERIE program, a set of clinical trials in healthy adults without obesity. In the main two-year trial, participants were coached to aim for a 25% reduction in calories, but on average, they achieved a more moderate reduction of about 12%. Even at that level, they lost weight and improved several markers linked to long-term cardiometabolic health, including blood pressure, LDL cholesterol, triglycerides, insulin sensitivity, and inflammatory markers.[2–4]

Later analyses from the same research program suggested that calorie restriction may also affect biology more directly than weight alone. One study found improved thymic function and changes in inflammatory and immunometabolic pathways, while another found a small slowing in a DNA-methylation measure of biological aging. Those are promising findings, but they are still not the same as proving longer lifespan in humans.[4,5]

So the fairest summary is this: calorie restriction in humans appears capable of improving health-related biomarkers and may modestly influence some aging-related measures, but the long-term effects on actual lifespan remain uncertain.[1–5]

Why weight still matters

One reason calorie restriction attracts so much attention is that excess weight itself can raise the risk of serious disease. Overweight and obesity are associated with higher risks of type 2 diabetes, high blood pressure, heart disease, stroke, fatty liver disease, sleep apnea, osteoarthritis, and several cancers. That means that, for many people, the benefits of eating fewer calories may come partly from reaching or maintaining a healthier body weight.[3,8]

That does not mean thinner is always better, or that everyone should aggressively cut calories. It means that chronic overconsumption and excess adiposity can damage health, and that thoughtful weight reduction can be valuable when excess weight is part of the problem.[1,8]

How to reduce calories without sacrificing nutrition

The smartest version of calorie restriction is not just “eat less.” It is “eat more deliberately.” Nutrient-dense foods help because they deliver more protein, fiber, vitamins, minerals, and essential fats per calorie. In practice, that usually means building meals around vegetables, fruit, legumes, whole grains, yogurt or other dairy foods, eggs, seafood, nuts, seeds, and other minimally processed protein sources.[6]

It also means being honest about where calories often pile up without much nutritional return: sugar-sweetened beverages, desserts, large restaurant portions, alcohol, fried fast food, and highly processed snack foods. The problem with these foods is not that they contain literally “zero” nutrition in every case. The problem is that they can crowd out more nutrient-dense choices and make it easier to overshoot total energy intake.[6]

Home cooking can help, not because restaurant food is automatically bad, but because cooking for yourself makes it easier to control portion size, ingredients, and preparation methods. Baking, broiling, grilling, steaming, and using modest amounts of healthier fats can all make it easier to lower calories without turning meals into punishment.[6]

If a person needs a formal low-calorie plan, it should be individualized. Medically supervised low-calorie diets can be appropriate in some situations, but they are not something to improvise casually.[7]

What about intermittent fasting?

Intermittent fasting is often discussed alongside calorie restriction, but the two are not identical. Calorie restriction focuses on how much energy you consume. Intermittent fasting focuses on when you eat. In practice, some people do consume fewer calories when they limit their eating window or skip certain meals, so intermittent fasting can become one way of achieving calorie reduction.[1,9]

The catch is that intermittent fasting does not appear to have a clear advantage over conventional reduced-calorie advice for weight loss. A 2026 Cochrane review found little to no difference between intermittent fasting and traditional dietary advice for most weight-loss outcomes in adults with overweight or obesity. That means intermittent fasting may be useful for some people, but it should be treated as an option, not magic.[9]

Risks and precautions

Calorie restriction is not appropriate for everyone. Older adults, people who are already underweight, people with chronic illness, and anyone with a history of disordered eating need special caution. The same is true for anyone considering a large or prolonged calorie deficit without professional guidance. When calorie restriction is done poorly, the downsides can include nutrient deficiencies, lean-mass loss, poorer bone health, fatigue, and mental stress around food.[1,7]

That is why it makes sense to talk with a physician or registered dietitian before making major dietary changes, especially if the goal is long-term restriction rather than a short-term cleanup of obvious excess calories.[6,7]

The bottom line

The evidence does not justify saying that calorie restriction is a proven anti-aging cure in humans. It does support a more careful claim: moderate calorie restriction, done without malnutrition, can improve several markers of metabolic health and may modestly influence biological aging. For many people, the practical payoff may be less about “living forever” and more about lowering disease risk, controlling weight more effectively, and improving long-term health.[1–5,8]

The best version of calorie restriction is not extreme. It is consistent, nutrient-aware, and sustainable. Eat fewer calories where excess is obvious, protect protein and overall nutrient quality, and build a plan you can actually live with.[1,6–8]

References

Flanagan, E.W.; Most, J.; Mey, J.T.; Redman, L.M.; Stover, P.J.; Balling, R. Calorie Restriction and Aging in Humans. Annu. Rev. Nutr. 2020, 40, 105–133.

Ravussin, E.; Redman, L.M.; Rochon, J.; Das, S.K.; Fontana, L.; Kraus, W.E.; Romashkan, S.; Williamson, D.A.; Meydani, S.N.; Villareal, D.T.; et al. A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity. J. Gerontol. A Biol. Sci. Med. Sci. 2015, 70, 1097–1104.

Kraus, W.E.; Bhapkar, M.; Huffman, K.M.; Pieper, C.F.; Das, S.K.; Redman, L.M.; Villareal, D.T.; Rochon, J.; Roberts, S.B.; Ravussin, E.; et al. 2 Years of Calorie Restriction and Cardiometabolic Risk (CALERIE): Exploratory Outcomes of a Multicentre, Phase 2, Randomised Controlled Trial. Lancet Diabetes Endocrinol. 2019, 7, 673–683.

Spadaro, O.; Youm, Y.; Shchukina, I.; Ryu, S.; Sidorov, S.; Ravussin, A.; Nguyen, K.; Aladyeva, E.; Predeus, A.N.; Smith, S.R.; et al. Caloric Restriction in Humans Reveals Immunometabolic Regulators of Health Span. Science 2022, 375, 671–677.

Waziry, R.; Ryan, C.P.; Corcoran, D.L.; Belsky, D.W.; Huffman, K.M.; Pieper, C.F.; Kulkarni, A.S.; Kim, K.; Wang, Y.; Liu, Y.; et al. Effect of Long-Term Caloric Restriction on DNA Methylation Measures of Biological Aging in Healthy Adults from the CALERIE Trial. Nat. Aging 2023, 3, 248–257.

U.S. Department of Agriculture; U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025, 9th ed.; USDA/HHS: Washington, DC, USA, 2020.

MedlinePlus. Diet for Rapid Weight Loss. 

National Institute of Diabetes and Digestive and Kidney Diseases. Health Risks of Overweight & Obesity. 

Garegnani, L.I.; Oltra, G.; Ivaldi, D.; Burgos, M.A.; Andrenacci, P.J.; Rico, S.; Boyd, M.; Radler, D.; Escobar Liquitay, C.M.; Madrid, E. Intermittent Fasting for Adults with Overweight or Obesity. Cochrane Database Syst. Rev. 2026, 2, CD015610.