Caloric Restriction as Panacea of Human Aging
Since ancient times, it’s a dream of humanity to drown in the fountain of youth. For last eight decades since 1916, scientists have come to know that Caloric restriction with optimal nutrition has role in life extension and showed promising results in many test subjects, such as rhesus monkeys, mice, yeast and worms. In 1935, Dr. Clive McCay—a nutrition researcher at Cornell University—discovered from mice experiments that mice which were on 30% caloric restriction exhibited 40% life extension as compared to normally-fed mice. This showed inter-linkage of caloric restriction and healthy aging. ScienceDaily and Scientific American Magazines have also interesting reads which suggest that caloric restriction has role in preventing negative effects of aging at cellular level and even five days of hunger may lead to reduction of age related diseases. In addition, US dietary guidelines and scientific societies have adopted caloric restriction as possible regiment to control body weight [1,2].
What is Calorie Restriction?
Above all, caloric restriction role in life extension is obvious from recently published research. Now questions arises that is Caloric Restriction and Fasting same or interchangeable in meaning? For instance, you may have come to know about fasting diets or caloric restriction diet plans and you wonder that why these are becoming increasingly popular. Is the only purpose of caloric restriction limited to weight loss? In reality “No“, caloric restriction and fasting are not the same. Therefore, in caloric restriction, we only limit our daily average caloric intake below our habitual or typical diet patterns without incurring malnutrition or deficiency of essential nutrients. However, in fasting diets, individuals do not eat during certain intervals of the daytime, week or month. In addition, caloric-restriction diet plans are not merely weight-loss plans, but researchers have shown that calorie restriction has role in life extension by causing delays in onset of age-related diseases [3,6].
Caloric Restriction Theory and Life Extension
Without incurring malnutrition, calorie restriction diet is part of the dietary regimen as a replacement for lack of physical activity in daily lives which focuses on caloric reduction to lose weight to stay fit, improve brain function due to low-carb consumption, increase life span, prevent gradual body weight gain, cardiovascular diseases, blood pressure, diabetes, excessive muscle, age related diseases, mass and live longer by promoting digestive health through positive changes on gut microbiota. Furthermore, studies show that effects of caloric restriction depend on various factors, such as type of calorie restriction diet, forms of caloric restriction employed, body weight status, perception about calorie intake and calorie diets . In short, caloric restriction is one of the sub-domains of the theory of aging which endorses role of caloric restriction in life extension. Main notions about caloric restriction theory involves:
- Caloric restriction and longevity (life extension)
- Caloric restriction and aging phenomenon
- Effects of caloric restriction on immune system
- Health benefits of fasting and caloric restriction
- Possible negative effects of caloric restriction
- Relationship of caloric restriction with theory of aging
- Calorie restriction vs fasting
- Health status of calorie restriction society
- Calorie intake effect on weight loss, life span and age-related diseases
The anti-aging scientists are actively exploring the facts hidden behind aging process. Several aspects have been brought to light in view of published research which suggests that there are several ways to live a healthy life. Research ranging from yeast to primates suggests life span extension to as much as one-third by enforcing caloric restriction in our daily lives.
The Health Diary is a weekly series which keeps on informing people about habits that help people to live well. David Sinclair—a professor in longevity research domain at Harvard University—is one of the most distinguished and notable scientists, known globally, whose active research area is longevity and coauthored a wonderful book titled Lifespan with Matthew D. LaPlante. He has staunch belief that humanity will succeed one day to be able to reverse aging process. Sinclair devoted much of his life researching the pathways having significant control on aging in human body.
Sirtuins, Nicotinamide Adenine Dinucleotide (NAD) & Resveratrol
During last decade, published research in Cell Journal from collaborative work of Sinclair group with scientists from the National Institute of Health (NIH), Harvard Medical School, National Institute on Aging and Cornell Medical School has revealed two geneses playing their roles for cellular longevity when undergo different kinds of stressors, such as caloric restriction . Caloric restriction led these genes to reverse ageing and mitigate cellular machinery from aging effects. Sinclair group collaborative work has discovered class of genes known as Sirtuins (SIRT1, SIRT3 and SIRT4) which have most significant impact on longevity because of stimulation by red-wine, berries and peanuts antioxidant-like molecule, known as Resveratrol. Along with caloric restriction and Resveratrol, Nicotinamide Adenine Dinucleotide (NAD) is also involved in cellular optimization to help better aging .
Caloric Restriction-Life Extension Phenomenon
Since long, scientists know that mitochondria serve as powerhouse of cells and has role in keeping cells healthy. Caloric restriction causes cells to activate a gene NAMPT which in turn leads to accumulation of NAD in mitochondria. As a result, NAD accumulation causes an increase in activity of enzymes created by SIRT3 and SIRT4 genes. How amazing this relationship is! Surprisingly, the mitochondria become stronger and energy-rich which consequently leads to slowing of cellular aging process. Same happens when we exercise so please do not underestimate the impact of exercise on your healthy aging and longevity. Hence, caloric restriction may modulate biochemical pathways which may attenuate cellular health and maintain stronger mitochondria. Even cells deprive of all energy sources, still the intact and functional mitochondria may keep cells alive.
Sinclair and others research declared mitochondria as guardian of cell survival. Aging-related diseases are now focused to be treated by targeting SIRT3 and SIRT4 genes [2-5]. Caloric restriction improves mitochondrial function and hence scientists have shifted their keen focus to treating lifestyle related disorders, such as cancer, neurodegeneration and diabetes by modulating Sirtuins. In an article published by Alexandra Sifferlin on medium, it is quoted on Professor Sinclair behalf that low-caloric diets/ caloric restriction diet plan and fasting have potential benefits for life extension. According to Sinclair, caloric restriction involves meal skipping and is type of informal intermittent fasting. It is one of key research areas in longevity research.
Effects of Caloric Restriction
Caloric restriction is easy to practice by skipping full-meal lunch, and instead replacing with dietary intake of small amount of soup or Sushi—according to Professor Sinclair. Moreover, Michael Mason in an article of New York times narrated by reviewing published literature that caloric restriction diets/ caloric restriction diet plan allows the animals to show more resistance to environmental stressors like radiation, heat and oxidation. Researchers theorize the underpinning body phenomenon that caloric restriction activates the cells to redirect energy to phenomena of repair and maintenance and hence, caloric-restricted cells are more efficiently scavenging free radicals, repairing mutations and using energy. The final goal of adopting caloric restriction is to avail longevity with healthy aging.
Caloric Restriction with Optimal Nutrition and Exercise
In a recent Nature publication, researchers regarded calorie restriction as the most reasonable anti-ageing intervention owing to the fact that caloric restriction slows down the metabolism which suggests that caloric restriction may help to achieve healthy aging and even life extension [3-6]. The panacea of human aging is also demystified by answering the question of what is better for life extension: caloric restriction or exercise in a recent paper published by American College of Sports Medicine in Exercise and Sports Science Reviews Journal. The article explains that exercise is only effective for secondary causes of aging while caloric restriction addresses primary causes of aging process. In reality as endorsed by Professor David Sinclair, both caloric restriction and exercise work in complementarity to modulate overlapping longevity signals.
The Calorie Restriction Society for Awareness of Caloric Restriction-Life Extension
For awareness of public about caloric restriction benefits, The Calorie Restriction Society was created by Swedish philosopher Brian M. Delaney in 1994. The primary aim of this Calorie Restriction Society is promotion of scientific discussion related to topics of longevity, healthy aging and life extension, caloric restriction with optimal nutrition, attracting large number of people to learn and adopt scientifically proven genuine life-extending principles of calorie restriction. They regularly publish about relationship of caloric restriction and aging, caloric restriction as optimal nutrition, and provide guidance about caloric restriction calculator .
In conclusion. without incurring malnutrition, caloric restriction is part of dietary regimen which focuses on caloric reduction. However, further research is needed to evaluate potential risk factors and negative effects of long-term caloric restriction in humans. Caloric restriction diet plan extends lifespan and caloric restriction benefits include reduction of incidence of several lifestyle related and age-related diseases, such as obesity, cardiovascular disease, oxidative stress, cancer and diabetes.
 Calorie Restriction and Fasting Diets: What Do We Know? (2019). National Institute on Aging. U.S. Department of Health and Human Services. https://www.nia.nih.gov/health/calorie-restriction-and-fasting-diets-what-do-we-know
 Eat Less to Live Longer: Calorie Restriction Linked to Long Healthy Lives. (2007). Harvard Medical School. https://www.sciencedaily.com/releases/2007/09/070920122209.htm
 The Hunger Gains: Extreme Calorie-Restriction Diet Shows Anti-Aging Results. (2017). https://www.scientificamerican.com/article/the-hunger-gains-extreme-calorie-restriction-diet-shows-anti-aging-results/
 Ravussin, E., Gilmore, L. A., & Redman, L. M. (2016). Calorie restriction in humans: Impact on human health. In Molecular basis of nutrition and aging (pp. 677-692). Academic Press. https://www.sciencedirect.com/topics/medicine-and-dentistry/caloric-restriction
 The New York Times; One for the Ages: A Prescription That May Extend Life (Michael Mason) (2006). https://www.nytimes.com/2006/10/31/health/nutrition/31agin.html
 Calorie restriction. https://en.wikipedia.org/wiki/Calorie_restriction