The CRON-diet (Calorie Restriction with Optimal Nutrition) [1] is a nutrient-rich, reduced calorie diet developed by Roy Walford, Lisa Walford, and Brian M. Delaney. [2] The CRON-diet involves calorie restriction in the hope that the practice will improve health and retard aging, while still attempting to provide the recommended daily amounts of various nutrients. [3] Other names include CR-diet, Longevity diet, and Anti-Aging Plan. The Walfords and Delaney, among others, founded the CR Society International to promote the CRON-diet. [4]
There is no experimental evidence that calorie restriction can slow biological aging in humans. [5] [6] The biological mechanisms for the supposed antiaging effects are not determined, as of 2021. [5]
The CRON-diet was developed from data Walford compiled during his participation in Biosphere 2 from 1991 to 1993. The subjects ate a diet low in fat and in calories but "nutrient-dense", derived from the food crops raised inside the Biosphere. [7] [8]
The writer Christopher Turner in The Telegraph reported that Walford claimed that the diet "will retard your rate of ageing, extend lifespan (up to perhaps 150 to 160 years, depending on when you start and how thoroughly you hold to it), and markedly decrease susceptibility to most major diseases." [3] The same article noted however that the diet "failed to dramatically increase Walford's lifespan; he died in 2004 aged 79." [3]
A review of the effects of calorie restriction in humans by Anna Picca and colleagues in 2017 noted that direct evidence was limited to what had been "recorded from the members of the Calorie Restriction Society, who have imposed on themselves a regimen of severe CR with optimal nutrition (CRON), believing to extend in this way their healthy lifespan." [9] The review noted that bone density was reduced but that bone strength was improved and maximal aerobic capacity per unit body mass was maintained or increased, while measures of quality of life including depression and physical function were improved. The review observed that one outcome had been the development of calorie restriction mimetic drugs which would be tested in clinical trials on humans. [9]
The journalist Pagan Kennedy wrote an opinion piece for The New York Times , mentioning Walford's book The 120 Year Diet and his hope of living for more than 100 years on the CRON diet, noting that instead he died of Lou Gehrig disease at age 79: her piece was titled "The Secret to a Longer Life? Don't Ask These Dead Longevity Researchers". [10]
The journalist Emily Yoffe tried the CRON-diet for Slate . She wrote that Walford had written a book about the diet called Beyond the 120 Year Diet, in which a "typical dinner" consisted of salad, lentils, brown rice, bulgur, a stalk of broccoli, and a glass of skimmed milk. [11] [12] Yoffe reported that after more than 2 months on the diet, she had not experienced the promised results: her "very poor" sleep had not improved much; her "energy" remained low; her "foggy mind" was still foggy. But she was pleased that she once again could experience loose-fitting pants. [11]
Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", "immortalists", or "longevists", postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.
Longevity may refer to especially long-lived members of a population, whereas life expectancy is defined statistically as the average number of years remaining at a given age. For example, a population's life expectancy at birth is the same as the average age at death for all people born in the same year.
Maximum life span is a measure of the maximum amount of time one or more members of a population have been observed to survive between birth and death. The term can also denote an estimate of the maximum amount of time that a member of a given species could survive between birth and death, provided circumstances that are optimal to that member's longevity.
The Okinawa diet describes the traditional dietary practices of indigenous people of the Ryukyu Islands, which were claimed to have contributed to their relative longevity over a period of study in the 20th century.
A low-protein diet is a diet in which people decrease their intake of protein. A low-protein diet is used as a therapy for inherited metabolic disorders, such as phenylketonuria and homocystinuria, and can also be used to treat kidney or liver disease. Low protein consumption appears to reduce the risk of bone breakage, presumably through changes in calcium homeostasis. Consequently, there is no uniform definition of what constitutes low-protein, because the amount and composition of protein for an individual with phenylketonuria would differ substantially from one with homocystinuria or tyrosinemia.
Roy Lee Walford, M. D. was a professor of pathology at University of California, Los Angeles School of Medicine, a leading advocate of calorie restriction for life extension and health improvement, and a crew member of Biosphere 2.
Calorie restriction mimetics (CRM), also known as energy restriction mimetics, are a hypothetical class of dietary supplements or drug candidates that would, in principle, mimic the substantial anti-aging effects that calorie restriction (CR) has on many laboratory animals and humans. CR is defined as a reduction in calorie intake of 20% to 50% without incurring malnutrition or a reduction in essential nutrients. An effective CRM would alter the key metabolic pathways involved in the effects of CR itself, leading to preserved youthful health and longer lifespan without the need to reduce food intake. The term was coined by Lane, Ingram, Roth of the National Institute on Aging in a seminal 1998 paper in the Journal of Anti-Aging Medicine, the forerunner of Rejuvenation Research. A number of genes and pathways have been shown to be involved with the actions of CR in model organisms and these represent attractive targets for drug discovery and for developing CRM. However, no effective CRM have been identified to date.
Calorie restriction is a dietary regimen that reduces the energy intake from foods and beverages without incurring malnutrition. The possible effect of calorie restriction on body weight management, longevity, and aging-associated diseases has been an active area of research.
Brian Manning Delaney is a venture investor and researcher in the biogerontology space. Delaney is a partner at the longevity biotech venture fund Emerging Longevity Ventures. Previously he was a philosophy professor and translator of the works of Hegel. He divides his time between Stockholm and the U.S.
Following is a list of topics related to life extension:
Leonard Pershing Guarente is an American biologist best known for his research on life span extension in the budding yeast Saccharomyces cerevisiae, roundworms, and mice. He is a Novartis Professor of Biology at the Massachusetts Institute of Technology.
The following outline is provided as an overview of and topical guide to life extension:
Sirtuin 1, also known as NAD-dependent deacetylase sirtuin-1, is a protein that in humans is encoded by the SIRT1 gene.
CALERIE is a trial currently underway in the U.S. to study the effects of prolonged calorie restriction on healthy human subjects.
The anti-aging movement is a social movement devoted to eliminating or reversing aging, or reducing the effects of it. A substantial portion of the attention of the movement is on the possibilities for life extension, but there is also interest in techniques such as cosmetic surgery which ameliorate the effects of aging rather than delay or defeat it.
The CR Society International is a nonprofit 501(c)(3) organization that was previously known as the CR Society or Calorie Restriction Society.
Valter D. Longo is an Italian-American biogerontologist and cell biologist known for his studies on the role of fasting and nutrient response genes on cellular protection aging and diseases and for proposing that longevity is regulated by similar genes and mechanisms in many eukaryotes. He is currently a professor at the USC Davis School of Gerontology with a joint appointment in the department of Biological Sciences as well as serving as the director of the USC Longevity Institute.
Genetics of aging is generally concerned with life extension associated with genetic alterations, rather than with accelerated aging diseases leading to reduction in lifespan.
This timeline lists notable events in the history of research into senescence or biological aging, including the research and development of life extension methods, brain aging delay methods and rejuvenation.
The relationship between diet and longevity encompasses diverse research studies involving both humans and animals, requiring an analysis of complex mechanisms underlying the potential relationship between various dietary practices, health, and longevity.
Brian M. Delaney, President of the CR Society since its early days, was one of several who created the Society. The Society was born in late 1994 when Steven Mehalek (who had the idea to meet), Rupert Hazle, Terry Savery, Lisa Walford, Roy Walford, and Brian M. Delaney got together at meeting of the Academy of Anti-Aging Medicine in Las Vegas.