To maintain optimum health, famous mid-century nutritionist Adelle Davis advocated the following practice: “Eat breakfast like a king, lunch like a prince, and dinner like a pauper.”But what if you ate every meal as leanly as possible? You could live longer.That’s the aim of those following the caloric restriction movement, nicknamed “CR” by its advocates. The idea is to pack all the nutrients you need to be healthy into as few calories as possible. Everyday staples of the American diet like burgers and fried chicken are banished for low calorie, nutrient-dense options like sweet potatoes and green and yellow vegetables, with little meat, eggs or dairy products.RESEARCH: Skipping Breakfast Linked to Heart Disease RiskConsidering the barrage of studies regarding the benefits of calorie restriction, some scientists contend that near-starvation can potentially be the most powerful tool we have to combat aging and ultimately extend our lives.The research claims sound nothing short of miraculous to would-be Ponce de Leons. Caloric restriction (CR) has been linked to the reduction of cardiovascular disease, diabetes, cancer, memory loss and most significantly, increased longevity in lab animals. A recent study on mice even linked CR to preventing infertility. All it takes is a little—make that a lot—of self-discipline.Exactly how CR works is still debatable. While multiple theories abound, one—hormesis—stands out due to its parallels with anti-aging techniques already widely used in the beauty industry: Just as a laser can damage skin cells in order to increase collagen production, this hypothesis contends that the CR diet imposes a low-level measure of biological stress on the body, which provokes a defensive response that helps to delay aging.But don’t look to CR to preserve a youthful complexion. Ever hear of another saying? “When you get older, you have to be ready to trade your ass for your face?”Well, consider an observation made by Dr. Elissa Epel, an associate professor in the University of California, San Francisco’s Department of Psychiatry who is involved in CRONA (Caloric Restriction with Optimal Nutrition and Aging Study), an investigation  probing the biological processes affected by extremely low calorie intake: “One thing we notice in people doing CR is that because they have so little body fat, including facial adiposity, they actually look more, not less wrinkled,” she said. “Just as people who lose a lot of weight might show more wrinkles.”QUIZ: How Healthy is Your Body? While CR seems to considerably slow the aging process in lab mammals (which suggests that the positive effects may extend to humans), the CRONA study is the first to study the psychology of people who are able to maintain such an extreme diet.Because the reality is, how many people can practice what CR enthusiasts preach?For example, the line between malnutrition and significantly reduced calories seems fine, at best. (Epel sheds some light on the diet: “They don’t eat empty calories. Modern calorie restriction means ‘optimal nutrition.’ They take great care to make each calorie count in terms of nutrition.” Similarly, the Calorie Restriction Society (or CRS) recommends a number of extremely specific diet plans to follow and suggests consulting a physician before embarking on a CR diet.)MORE: Calorie Count on Menus are UnderstatedMerely drastically reducing your nutritional intake will not only lead to unhealthy, rapid weight loss, but again, can potentially cause malnutrition. Some critics even claim the practice could contribute to eating disorders. To reap the documented benefits, an adult would have to practice the monk-like attitude towards food consistently for years, which is highly unrealistic. In fact, growing children and adolescents are discouraged from the practice, as studies in mice found it inhibited development.Enter the magic bullet: A pill called Rapamycin.Recent studies on this drug are being compared to the research on CR, due to reportedly similar anti-aging effects. The difference is, with the pill you don’t have to worry about food restriction. David Harrison, Ph.D. and professor at The Jackson Lab in Bar Harbor, ME, who is involved in Rapamycin research, points out, “We’re talking about a pill that could work even later in life, as opposed to a lifetime of intense calorie deprivation. Our mice ate normally.”Rapamycin, also known as Sirolimus, is obtained from a substance found in the soil of Easter Island. Due to its immunosuppressant capabilities, it’s used to prevent rejection in organ transplant patients. Here’s the surprising part: In lab mice, rapamycin has so far been effective in extending their lifespans by up to 13 percent.A reason it gets lumped in with CR? “In my opinion, it is likely that rapamycin provides some, but not all, of the health benefits of CR,” says Matt Kaeberlein of the Kaeberlein Lab and co-director of the University of Washington’s Nathan Shock Center of Excellence in the Basic Biology of Aging, who also alludes to the idea that inhibition of the mTOR pathway (rapamycin’s cellular target) is one of the major ways that CR slows aging.“Certainly, it is now clear that rapamycin can extend life span in simple organisms (yeast, worms, and flies) as well as mice. It remains to be seen whether rapamycin also delays the onset of a variety of age-related diseases (like CR does),” says Kaeberlein.The very fact that it can be taken in pill form makes it not only attractive for health reasons, but also ripe for exploitation by the beauty and anti-aging industry.Assuming the side effects of Rapamycin—immune suppression makes the recipient more susceptible to infections such as pneumonia—are circumvented in the future, could this drug theoretically have a potential impact on the physical signs of aging?“Possibly, yes,” Kaeberlein surmises. But he cautions that so far, there simply isn’t any concrete data to suggest this is the case.“In both mice and monkeys, aged CR animals are described as appearing more youthful relative to age-matched controls,” he says. “I’m not sure the same can be said for people who are self-practicing CR, although we don’t really have a large enough comparison group who are elderly and have been on CR for many years. In theory, if an intervention slows aging then the physical and cognitive aspects of aging should be slowed.”Dr. Harrison, who has performed and is involved in extensive studies on rapamycin, says that while its implications for longevity and delaying disease are promising and downright “exciting,” is more skeptical when it comes to any superficial implications. In his opinion, those searching for the physical fountain of youth should turn a well-lined cheek and focus on the revolutionary potential health benefits that rapamycin may provide to future generations.MORE: Can You Erase Wrinkles with a Pill?“An important component of anti-aging is collagen production, but what we saw in the connective tissue of extracted tendon fibers from the mice’s tails indicated a denaturation process in terms of the collagen becoming less elastic and aging faster, if anything,” he said. “But I don’t want to talk about that too much because the truth is there’s a difference between tail tendon fibers and human skin. We simply haven’t done that research in terms of the look of aging and this drug.“Let’s just say at this stage, there’s not only no evidence to suggest that rapamycin will prevent wrinkles, but some evidence that points to the opposite. It might prevent you from getting cancer, but in terms of what we now know, not necessarily keep you baby-faced. Bottom line is, if you want to prevent aging, wear a hat when you go outside!”That’s advice we can certainly agree with.QUIZ: How Healthy Do You Feel?