Yes, restricting calories can be good for your health. But it has never been proven that eating less can make you live longer. At least not in humans.
Rats with a 60% longer lifespan
As far back as the 1930s, scientists found that a calorie-restricted diet can extend the lifetime of many animals, including flies, mice and even trout. Clive McCay, a pioneer of low-calorie research, showed in 1935 that rats following a calorie-restricted diet lived 60% longer (i.e., 800+ days, vs. 500 days) than rats fed normally.
To find out if the same holds true for primates, two studies were launched in the late 1980s on macaques, which typically live around 30 years (in captivity). When the longevity data was analyzed in January 2017, researchers found that a calorie-restricted diet among adult macaques extended their lifespans by three years. What’s more, age-related illnesses such as cardiovascular disease, cerebral atrophy, cancer and diabetes appeared later in these adults. The researchers believe the same effects could be found in humans, but that has never been proven. By definition, scientists have to wait a lifetime to find out if their longevity hypotheses are correct!
Healthier for longer
For the short term, however, volunteers have been willing to test the health benefits of a low-calorie diet. One such study is the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) program, which looked at the consequences of following a diet that is 25% lower in calories for two years. The researchers found the same metabolic and molecular changes among the volunteers as had previously been found in animals. And those changes could reduce the risk of developing age-related illnesses like diabetes, high blood pressure, cardiovascular disease, cancer and dementia.
But even if eating less won’t necessarily extend your lifetime, it could at least extend the time of your life that you spend in good health.
It’s worth bearing in mind that not all volunteers in the CALERIE program had enough willpower to stick to the strict diet. Most reduced their calorie intake by only 12%, and their bodies didn’t all respond to the diet in the same way.
The effects of calorie restriction can vary depending on your specific genetic make-up. For some people, calorie restriction can even be dangerous. The safety and feasibility of such diets need to be researched further.
The Effect of Retarded Growth Upon the Length of Life Span and Upon the Ultimate Body Size, J. Nutr. 1935 10: 1 63-79
Caloric restriction improves health and survival of rhesus monkeys, Nature Communications 8, 14063 (2017), DOI:10.1038/ncomms14063
Starving for Life: What Animal Studies Can and Cannot Tell Us about the Use of Caloric Restriction to Prolong Human Lifespan, J. Nutr. April 2007, vol. 137 no. 4 1078-1086
Two-Year Trial of Human Caloric Restriction, J Gerontol A Biol Sci Med Sci (2015) 70 (9): 1095-1096., DOI: https://doi.org/10.1093/gerona/glv100
Long-term calorie restriction is highly effective in reducing the risk for atherosclerosis in humans, PNAS, April 27, 2004, vol. 101 no. 17, DOI: 10.1073/pnas.0308291101
Caloric restriction: powerful protection for the aging heart and vasculature, American Journal of Physiology, Vol. 301 no. 4, H1205-H1219 DOI: 10.1152/ajpheart.00685.2011
Nutrition, Brain Aging, and Neurodegeneration, Journal of Neuroscience, 14 October 2009, 29 (41) 12795-12801; DOI: https://doi.org/10.1523/JNEUROSCI.3520-09.2009