The anti-aging diet, also called the calorie-restriction diet, is one that restricts calorie intake by 30%–50% of the normal or recommended intake with the goal of increasing human lifespan by at least 30%. When combined with a healthy lifestyle, people on the diet tend to have improved health, providing they consume adequate vitamins, minerals, and other essential nutrients.
The idea that a calorie-restrictive diet can significantly increase lifespan has been around since the 1930s. In 1935, Cornell University food researchers Clive McCay and Leonard Maynard published their first in a series of studies in which laboratory rats were fed a diet that had one-third fewer calories than a control group of rats. The lower-calorie diet still contained adequate amounts of vitamins, minerals, protein, and other essential nutrients. This calorie-restrictive diet provided much less energy than researchers had previously thought rats needed to maintain growth and normal activities. The rats on the lower-calorie diet lived 30%–40% longer than the rats on a normal calorie diet. Since then, more than 2,000 studies have been carried out, mostly on animals, investigating the connection between calorie restriction and increased longevity.
A reduced-calorie diet was taken a step further by University of California, Los Angeles, pathologist Roy Walford, who studied the biology of aging. In 1986, he published The 120-Year Diet and a follow-up book in 2000, Beyond the 120-Year Diet, in which he argued that human longevity can be significantly increased by adhering to a strict diet that contains all the nutrients needed by humans, but with about one-third the calories. In 1994, he coauthored The Anti-aging Plan: Strategies and Recipes for Extending Your Healthy Years. His anti-aging plan was based on his own research and that of other scientists, including his study of diet and aging conducted as chief physician of the Biosphere 2 project in Arizona in the early 1990s. It is important to note that the Biosphere project was considered a scientific failure and not unanimously respected in the scientific community. Walford was one of eight people sealed in Biosphere 2 from 1991 to 1993 in an attempt to prove that an artificial closed ecological system could sustain human life. He also cofounded Calorie Restriction Society International in 1994. Walford died in 2004 at the age of 79 from complications of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.
Anti-aging diets are regimens that reduce the number of calories consumed by 30%–50%, while allowing the necessary amounts of vitamins, minerals, and other nutrients the body needs to sustain itself and grow. Calorie restriction has been shown to increase the lifespan of various animals, including rats, fish, fruit flies, dogs, and monkeys, by 30%–50%. Studies have suggested that calorie restriction may increase the maximum human lifespan by about 30%. A problem preventing scientists from offering substantive proof that humans can greatly increase their lifespan by restricting calories is that the length of human lifespans would make full compliance with the diet difficult and would require exceptionally long times for scientific study as well as the involvement of several generations of scientists.
Despite calorie restriction, maintaining a balanced intake of nutrients is essential for achieving any anti-aging effects. People who experience starvation or famine receive no longevity benefits since their low-calorie intake contains inadequate nutrition. The calorie-restrictive diet is believed to most benefit people who start in their mid-twenties, with the beneficial effects decreasing proportionately with the age one begins the diet.
Although there are variations among Anti-aging diets, most reduced-calorie diets recommend a core set of foods. These include vegetables, fruits, fish, soy, low-fat or non-fat dairy products, nuts, avocados, and olive oil. These foods are high in essential nutrients, vegetable fiber, and phytochemicals and have low glycemic values. The primary beverages recommended are water and green or black tea.
Guidelines on calorie reduction vary from diet to diet, ranging from a 10% reduction to a 50% reduction of normal intake. Roy L. Walford (1924–2004), author of several books on Anti-aging diets, says a reasonable goal is to achieve a 10%–25% reduction in a person's normal weight based on age, height, and body frame. The Anti-aging diet recommends men of normal weight lose up to 18% of their weight in the first six months of the diet. For a six-foot male weighing 175 lb. (79.3 kg), that means a loss of about 31 lb. (14 kg). For a small-framed woman who is five-foot, six-inches tall and weighs 120 lb. (54.4 kg), the plan recommends losing 10% of her weight in the first six months, a loss of 12 lb. (5.4 kg).
Walford's anti-aging plan is a diet based on decades of animal experimentation. It consists of computer-generated food combinations and meal menus containing the United States Department of Agriculture's dietary reference intakes (formerly called recommended daily allowances) of vitamins and other essential nutrients using foods low in calories. On the diet, the maximum number of calories allowed is 1,800 per day. There are two methods for starting the diet: rapid orientation and gradual orientation.
The rapid orientation method allows people to eat low-calorie meals rich in nutrients. This is a radical change for most people and requires a good deal of willpower. All foods low in nutrients are eliminated from the diet. The nutritional value and calories in foods and meals is determined by a software program available for purchase from Calorie Restriction Society International.
The gradual orientation method allows people to adopt the diet over time. The first week, people eat a high-nutrient meal on one day. This increases by one meal a week until participants are eating one meal high in nutrients every day at the end of seven weeks. Other meals during the day consist of low-calorie, healthy foods, but there is no limit on the amount a person can eat. After two months, participants switch to eating low-calorie, high-nutrition foods for all meals. Dieters are advised to view this diet as a lifestyle change rather than a quick weight-loss program.
A sample one-day, low-calorie, high-nutrition menu developed by Walford is:
The three meals and snack contain 1,472 calories, 3.2 oz. (92 g) protein,.84 oz. (24 g) fat, 8.3 oz. (234 g) carbohydrates,.95 oz. (27 g) fiber, and 10.9 oz. (310 g) cholesterol.
The goal of the Anti-aging diet is to slow the aging process, thereby extending the human lifespan. Even though it is not a weight loss diet, people taking in significantly fewer calories than what is considered normal by registered dietitians are likely to lose weight. Exercise is not part of calorie reduction diets. Researchers suggest people gradually transition to a reduced calorie diet over one or two years since a sudden dramatic calorie reduction can be unhealthy and even shorten the lifespan.
A reduced-calorie diet is not recommended for people under the age of 21 as it may impair physical growth. This impairment has been seen in research on young laboratory animals. In humans, mental development and physical changes to the brain occur in teenagers and people in their early 20s that may be negatively affected by a low-calorie diet.
Other individuals advised against starting a calorie-restricted diet include women who plan to become pregnant, women who are pregnant, and those who are breastfeeding. A low body mass index (BMI), which occurs with a low-calorie diet, is a risk factor in pregnancy and can result in dysfunctional ovaries and infertility. A low prepregnancy BMI increases the risk of premature birth and low birth weights in newborns. People with existing medical conditions or diseases should be especially cautious and consult with their physician before starting.
It is imperative that participants ensure that they continue to consume adequate levels of essential nutrients. Nutritional supplements and other forms of nutritional help are likely to be needed.
The Anti-aging diet is very restrictive, and dieters need to adhere strictly to diet plans to ensure that they are receiving required amounts of key nutrients. A wide range of risks, related to physical, mental, social, and lifestyle issues, is associated with such a low-calorie diet. They include:
Animal studies generally support the idea that a calorie-restrictive diet with adequate intake of essential nutrients increases lifespan. In some small studies, people consuming a calorie-restrictive diet (under 1,400 calories daily) for five or more years had better heart function and lower blood pressure than those who consumed a diet of more than 2,000 calories daily. It is not clear whether the benefits come only from calorie restriction or from the increased fruits, vegetables, fiber, and whole grains consumed on most of these diets.
As of the end of 2017, research studies showed that calorie restriction in humans caused some of the same metabolic and molecular adaptations that improved health and longevity models for animals. Calorie restriction in humans mitigated several metabolic and hormonal factors related to type 2 diabetes, cardiovascular diseases, and cancer. Studies were just beginning to examine the details of how these mechanisms are affected. For example, calorie-restricted diets seemed to decelerate aging by slowing down age-related epigenetic changes in mice and monkeys. Epigenetic changes occur in cells throughout the body and modify how genes are switched on and off with altering the DNA sequence.
By the end of 2017, several drugs were developed that were in, or were soon to be tested in, clinical studies on humans, which would provide anti-aging benefits. Although calorie restriction may improve human health spans, questions remained about potential negative effects. Restricting calories, especially if it is done too rigorously, can cause fatigue, nutrient deficiencies, reduced fertility, weaker bones, and decreased immunity. Conversely, some researchers found that calorie restriction improved people's mood, general health, sexual drive, relationships, and sleep while reducing tension. Calorie-restricted diets also seemed to reduce human body fat, which may help improve human life span.
See also Adult nutrition ; Anorexia nervosa ; Body mass index ; Calorie restriction ; Calories ; Dietary reference intakes (DRIs) ; Minerals ; Vitamins .
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American Aging Association, 2885 Sanford Ave. SW #39542, Grandville, MI, 49418, firstname.lastname@example.org, https://www.americanagingassociation.org .
Calorie Restriction Society International, 187 Ocean Dr., Newport, NC, 28570, (877) 511-2702, email@example.com, http://www.crsociety.org .
National Institute on Aging, Bldg. 31, Rm. 5C27, 31 Center Dr., MSC 2292, Bethesda, MD, 20892, (800) 222-2225, TTY: (800) 222-4225, Fax: (301) 496-1072, firstname.lastname@example.org, http://www.nia.nih.gov .
Ken R. Wells
Revised by Jeanie Simoncic, AM