The Key to a Long and Healthy Life
Written by Susan Parker | Updated on June 22, 2025
Reviewed by Susan Parker
11 sources cited
What if the key to living a longer and healthier life has been right in front of us for centuries? Calorie restriction—a concept endorsed by Benjamin Franklin and supported by modern research—could be a potential source of youthfulness. From prolonging the lifespan of animals by 40% to demonstrating positive outcomes in humans, this simple yet demanding practice may unlock the secret to improved health and longevity. But how does it function, and is it suitable for you? Let's explore the science and unexpected revelations.
Overview
Calorie Restriction (CR) Enhances Lifespan: Research on animals, including primates, indicates that CR can postpone aging and enhance longevity, especially when initiated in adulthood.
CR Improves Health Markers: CR decreases inflammation, DNA damage, and risk factors for heart disease, diabetes, and cancer, while enhancing mitochondrial function.
Adherence is Demanding: The mental and physical challenges of CR make sustained commitment difficult, yet the health benefits are substantial.
Calorie Restriction Goes Back Centuries
It’s as close to a genuine fountain of youth as you can get.
And yet it’s not new. It was originally proposed as a method of extending life in the 16th century and was endorsed by Benjamin Franklin two hundred years later.
In the 1930s, researchers demonstrated that, by following this straightforward advice, they could increase the maximum lifespan of rodents by an impressive 40%. Even cautious researchers are willing to acknowledge its effectiveness, not only in animals but also in humans.
The formula is incredibly simple. As Ben Franklin stated, “To lengthen thy life, lessen thy meals.”
Calorie Restriction For Life Extension
After the initial experiments conducted 80 years ago, scientists replicated them in various organisms such as yeasts, fruit flies, spiders, worms, mice, rats, fish, snakes, and dogs. A 2009 study by the University of Wisconsin-Madison (UWM) confirmed the effectiveness of calorie restriction in monkeys, enabling them to live three years longer than usual, from 26 to 29 years old, equivalent to about nine years in humans. Calorie restriction appears to successfully extend biological life across all tested organisms. It also promotes overall health. Individuals practicing it have a reduced incidence of disease. However, in 2012, a study by the National Institute of Aging (NIA) threw a wrench into the works. Contrary to all other studies, the researchers found that while it improved the health of rhesus monkeys, it did not extend their lifespan. This prompted a collaboration between the NIA and UWM to investigate the discrepancies.It Does Work After All
After scrutinizing many years of research and data from several hundred monkeys, the two research teams concluded that consuming fewer calories does extend the lifespan of these primates. The inconsistencies in their findings were attributed to various factors, including diet composition, feeding schedules, variations in origin, age, gender, body weight, and genetics of the monkeys. A crucial discovery was that reducing food intake does not benefit younger animals. Calorie restriction (CR) must be initiated during adult and senior years, at least among primates. (And in case you forgot your high school biology lessons, humans belong to the primate category.) According to the researchers, “Data from both study locations suggest that the CR paradigm is effective in delaying the effects of aging in nonhuman primates but that the age of onset is an important factor in determining the extent to which beneficial effects of CR might be induced. “CR mechanisms are likely translatable to human health.”Calorie Restriction in Humans
While over a thousand experiments since the 1930s confirm enhanced well-being and longevity in numerous species, the lifespan of humans makes it nearly impossible to conduct longevity studies. Nonetheless, several shorter studies have been carried out focusing on biological health indicators. In these studies, calorie consumption is typically reduced by about a quarter for one or two years. Results include improved heart function, reduced risk factors for cardiovascular disease, diabetes, and specific cancers, decreased markers for inflammation, and mitigation of DNA damage.There were also positive reductions in two recognized longevity biomarkers – body temperature and fasting insulin.
Another critical finding was an elevation in mitochondria (energy) production. The absence or dysfunction of cellular mitochondria is detrimental to both health and lifespan.
Excessive calorie restriction can lead to adverse effects, such as muscle loss, anemia, water retention, and neurological impairments. These outcomes were observed when calories were restricted by 45% for six months.
Individuals in their fifties following a diet with a 25% calorie reduction, without engaging in any physical activity, experienced declines in bone mineral density in the hip, spine, and thigh as well as reductions in muscle mass and aerobic capacity.
Individuals adhering to the CR diet – also known as the high/low or longevity diet – target approximately 1,500 calories per day for women and 1,800 calories per day for men, with a focus on highly nutritious foods. For a standard diet, the usual calorie recommendations are 2,000 for women and 2,500 for men.
The concept of eating less is straightforward, but it does not imply it is easy. It demands considerable determination. No one enjoys feeling hungry even for a few days, let alone adopting it as a lifelong practice. Compliance is often low even in human studies that reduce calories by only 16%.
If you decide to give it a try, please ensure you are under the supervision of your physician or another knowledgeable healthcare provider.
Summary
Calorie restriction (CR) entails reducing calorie intake without malnutrition and has been associated with extended lifespans and enhanced health in various species. Studies confirm that CR benefits primates, including humans, by decreasing disease risk, enhancing mitochondrial function, and reducing inflammation. However, commencing CR too early or excessively reducing calories can result in negative consequences. While the concept is simple, maintaining a CR lifestyle necessitates discipline and should be approached with medical guidance.
