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The anti-aging diet is one that restricts calorie intake by 30–50% of normal or recommended intake with the goal of increasing human lifespan by at least 30%. People on the diet also 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 of experiments in which laboratory rats were fed a diet that contained one-third less calories (compared to a control group of rats) but 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
(Illustration by GGS Information Services/Thomson Gale)
2,000 studies have been done, mostly on animals, about the connection between calorie restriction and increased longevity.
A reduced calorie diet was taken a step further by the 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 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 co-authored The Anti-Aging Plan: Strategies and Recipes for Extending Your Healthy Years. His anti-aging plan is based on his own research and that of other scientists. Included is his study of diet and aging conducted as chief physician of the Biosphere 2 project in Arizona in the early 1990s. 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 the Calorie Restriction Society in 1994.
Anti-aging diets are regimes 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. This calorie restriction has been shown to increase the lifespan of various animals, including rats, fish, fruit flies, dogs, and monkeys, by 30–50%. Some human studies have also been done—and longterm studies are underway— but evidence of its impact on humans is very limited compared to results available from the animal studies. The completed studies indicate that calorie restriction can increase the maximum human lifespan by about 30%. The problem preventing scientists from offering substantive proof that humans can greatly increase their lifespan by restricting calories is that the current maximum human lifespan is 110–120 years and full compliance with the diet is difficult. A 30% increase would extend the human lifespan to 143–156. This is an exceptionally long time for a scientific study and requires involvement of several generations of scientists. Only several hundred people have ever been documented to lived past age 110 and there are only two people with confirmed documentation who have lived to at least age 120: Jeanne Louise Calmet (1875–1997) of France who lived 122 years and 164 days; and Shigechiyo Izumi (1865–1986) of Japan who lived 120 years and 237 days, according to Guinness World Records.
Since 1980, dozens of books have been published offering specific calorie reduction diets aimed at increasing lifespan. The most popular diets include the Okinawa Diet, Anti-Inflammation Diet, Longevity Diet, Blood Type Diet, Anti-Aging Plan, and the 120-Year Diet.
Calorie restriction is a lifelong approach to eating by significantly lowering daily calorie intake while still getting all the body’s required nutrients. People who experience starvation or famine receive no longevity benefits since their low calorie intake contains little nutrition. The diet is believed to most benefit people who start in their mid-20s, with the beneficial effects decreasing proportionately with the age one begins the diet.
Although there are variations between 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. 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 Plan 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, that means a loss of about 31 pounds. For a small-framed woman who is five-foot, six-inches tall and weighs 120 pounds, the plan recommends losing 10% of her weight in the first six months, a loss of 12 lb.
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 all of the U.S. Department of Agriculture’s 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 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 are 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.
On his Web site (http://www.walford.com), Walford states: “Going for longevity on the Anti-Aging Plan requires caloric limitation. We advise, however, that you view this as a lifestyle change and not a quick-fix program or a diet. Any person can physiologically adapt to this level of limitation and experience no physical hunger provided that nearly every calorie eaten is a nutrient-rich calorie.”
A sample one-day low-calorie, high-nutrition menu developed by Walford is:
- Breakfast: One cup of orange juice, one poached egg, one slice of mixed whole-grain bread, and one cup of brewed coffee or tea.
- Lunch: One-half a cup of low-fat cottage cheese mixed with one-half a cup of non-fat yogurt and one tablespoon of toasted wheat germ, an apple, and one whole wheat English muffin.
- Dinner: Three ounces of roasted chicken breast without the skin, a baked potato, and one cup of steamed spinach.
- Snack: Five dates, an oat bran muffin, and one cup of low-fat milk.
The three meals and snack contain 1,472 calories, 92 g protein, 24 g fat, 234 g carbohydrates, 27 g fiber, and 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 nutritionists 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 calorie reduction can be unhealthy and even shorten the lifespan.
There is no clear answer as to why severely reducing calorie intake results in a longer and healthier life. Researchers have various explanations and many suggest it may be due to a combination of factors. One theory is that calorie restriction protects DNA from damage, increases the enzyme repair of damaged DNA, and reduces the potential of genes being altered to become cancerous. Other calorie reduction (CR) theories suggest:
- CR helps reduce the production of free radicals; unstable molecules that attack healthy, stable molecules. Damage caused by free radicals increases as people age.
- CR delays the age-related decline of the human immune system and improved immune function may slow aging.
- CR slows metabolism, the body’s use of energy. Some scientists propose that the higher a person’s metabolism, the faster they age.
The primary benefits of the anti-aging diet are improved health and prevention or forestalling diseases such as heart disease, cancer, stroke, diabetes, osteoporosis, Alzheimer’s, and Parkinson’s. Studies show that most physiologic functions and mental abilities of animals on reduced calorie diets correspond to those of much younger animals. The diet has also demonstrated extension of the maximum lifespan for most life forms on which it has been tested.
A reduced calorie diet is not recommended for people under the age of 21 since 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 on getting pregnant, women who are pregnant, and those who are nursing babies. 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 BMI also can cause premature birth and low birth weights in newborns. People with existing medical conditions or diseases are discouraged from reduced calorie diets. They should be especially cautious and consult with their physician before starting.
There are a wide range of risks associated with an anti-aging, reduced calorie diet. These risks include physical, mental, social, and lifestyle issues.
- Hunger, food cravings, and obsession with food.
- Loss of strength or stamina and loss of muscle mass, which can affect physical activities, such as sports.
- Decreased levels of testosterone, which can be compensated with testosterone supplementation
- Rapid weight loss (more than two pounds a week), which can negatively impact health
- Slower wound healing
- Reduced bone mass, which increases the risk of fracture
- Increased sensitivity to cold
- Reduced energy reserves and fatigue
- Menstrual irregularity
- Drastic appearance changes from loss of fat and muscle, causing people to look thin or anorexic
Social issues can arise over family meals, since not all family members may be on a reduced calorie diet. Conflict related to the types of food served, the amount of food served and the number of meals in a day, and fasting may develop. Other social issues involve eating in restaurants, workplace food, parties, and holidays. The long-term psychological effects of a reduced calorie diet are unknown. However, since a low calorie diet represents a major change in a person’s life, psychological problems can be expected, including anorexia, binging, and obsessive thoughts about food and eating.
An anti-aging diet that restricts calories may slow the aging of the heart and lengthen lifespan, according to a study by Washington University School of Medicine in St. Louis, Missouri. The small study, released in 2006, followed 25 people aged 41–65 who consumed only 1,400–2,000 calories a day for six years. Results of the study showed participants had heart functions that resembled people 15 years younger and their blood pressure was significantly lower than a control group who had a calorie intake of 2,000–3,000 per day, the amount of a normal Western diet.
A calorie-restrictive diet may reverse early stages of Parkinson’s disease, according to a study released in
2005 by the Oregon Health and Science University and the Portland Veterans Affairs Medical Center in Portland, Oregon. Researchers said mice in the early stages of Parkinson’s disease who had their calorie intake reduced by 50% had elevated levels of glutamate, an essential brain chemical that is lost due to Parkinson’s disease. Results of this study are optimistic, but further research is necessary to prove any level of effectiveness in humans.
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American Aging Association. The Sally Balin Medical Center, 110 Chesley Drive, Media, PA 19063. Telephone: (610) 627-2626. Website: <http://www.americanaging.org>.
American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, IL 60606-6995. Telephone: (800) 877-1600. Website: <http://www.eatright.org>.
Calorie Restriction Society. 187 Ocean Drive, Newport, NC 28570. Telephone: (800) 929-6511. Website: <http://www.calorierestriction.org>.
National Institute on Aging. Building 31, Room 5C27, 31 Center Drive, MSC 2292, Bethesda, MD 20892. Telephone: (800) 222-2225. Website: <http://www.nia.nih.gov>.
Ken R. Wells