Starving Yourself to Death Does Not Lead to Longer Life, But Maybe Some Benefits
New NIA study of monkeys shoots down long-held theory that severe calorie restriction increasess longevity
Aug. 31, 2012 – An old
joke among seniors has been, “If you want to live a long life, you have to starve yourself to death.” It was based on a long-held theory that
severe diet restriction extended life – most of this testing had been on rodents. That theory just got deflated by a new study from scientists
at the National Institute on Aging who say this drastic diet does not add years to your life.
They found that calorie restriction - a diet of approximately 30 percent fewer calories but with the same nutrients of a
standard diet — does not extend years of life or reduce age-related deaths in a 23-year study of rhesus monkeys. However, calorie restriction
did extend certain aspects of health, says the report in the August 29, 2012, online issue of Nature.
Calorie restriction research has a long history. The first finding came in the 1930s, when investigators observed
laboratory rats and mice lived up to 40 percent longer when fed a calorie-restricted diet.
Subsequent research has cited calorie restriction as extending lifespan of yeast, worms, flies and some strains of mice.
But other studies have not shown a longevity benefit. For example, in studies of certain strains of mice, calorie restriction on average had
no effect on lifespan. Some of these mice actually had a shorter lifespan when given a calorie-restricted diet.
To date, research does not provide evidence that calorie restriction is an appropriate age regulator in humans, the NIA
investigators point out. Currently, limited human studies are under way to test the effectiveness and safety of calorie restriction in people.
The survival results in the study reported today by NIA researchers differ from those published in 2009 by NIA-supported
investigators at the University of Wisconsin-Madison. The Wisconsin study followed two groups of rhesus monkeys for 20 years and found that
monkeys on a calorie-restricted diet lived longer than those on a standard diet.
Beyond longevity, the parallel NIA and Wisconsin studies have reported similar beneficial health effects of
calorie-restriction. Both studies found that certain age-related diseases — including diabetes, arthritis, diverticulosis and cardiovascular
problems — occurred at an earlier age in monkeys on the standard diet compared to those on calorie restriction. However, this observation was
not statistically significant in the NIA study.
NIA researchers did find that monkeys started on calorie restriction at an early age had a statistically significant
reduction in cancer incidence.
NIA researchers also found that while calorie restriction had a beneficial effect on several measures of metabolic health
and function in monkeys who were started on the special diet regimen during old age (at 16 to 23 years), it did not have the same positive
outcome for monkeys started on calorie restriction at a young age (less than 14 years). In the Wisconsin study, all the monkeys were 7 to 14
years when started on calorie restriction.
"These results suggest the complexity of how calorie restriction may work in the body," said NIA Director Richard J.
Hodes, M.D. "Calorie restriction’s effects likely depend on a variety of factors, including environment, nutritional components and genetics."
Differences in the monkeys' meal and other nutritional factors were cited as possible explanations for NIA’s and
Wisconsin’s different outcomes. Both studies used a similar percentage of calorie restriction with their intervention groups; however, the
Wisconsin monkeys in both the calorie restricted and control groups were eating more and weighed more than the matched NIA monkeys.
NIA's food had a natural ingredient base, while Wisconsin opted for a purified diet. Purified diets generally lack trace
dietary chemicals and minerals that could affect an animal’s health. Each ingredient of a purified diet provides a specific nutrient and
minerals or vitamins must be added separately.
Natural-ingredient diets have risk of variation between batches, but are considered by some to be more complete than
purified diets. NIA and Wisconsin also used different sources for proteins, fat and carbohydrates, as well as different approaches to vitamin
and mineral supplementation.
"There is no right or wrong nutritional approach to calorie restriction, but the differences should be considered as we
try to understand the dissimilar effects of calorie restriction between the two studies," said first author Julie A. Mattison, Ph.D., facility
head of NIA’s Nonhuman Primate Studies Unit, part of the Laboratory of Experimental Gerontology.
NIA researchers cited genetics as another possible reason for their differing results. NIA monkeys had a greater genetic
diversity, originating from China and India. Wisconsin's monkeys came only from an Indian colony.
"We've learned more by having two concurrent and independent studies of calorie restriction in monkeys than would have
been possible by just the NIA or Wisconsin study alone. While the two studies share many of the same findings, the differences will be
particularly important for helping us better understand this aging intervention," said Felipe Sierra, Ph.D., director of NIA's Division of
As scientists measure the possible outcomes of calorie restriction, research is also focusing on finding the mechanisms
and pathways by which calorie restriction may influence longevity and the risk of age-associated disease.
"My laboratory and other researchers are looking at calorie restriction’s effects on cell metabolism, gene expression,
insulin signaling pathways and other basic biological processes to pinpoint how reducing calorie intake may attenuate the negative
consequences of aging. We are looking at whether compounds can mimic the effects of calorie restriction via these mechanisms," said senior
author, Rafael de Cabo, Ph.D., chief of the Mechanisms and Interventions of Aging section of NIA’s Laboratory of Experimental Gerontology.
The NIA leads the federal government effort conducting and supporting research on aging and the health and well-being of
older people. The Institute’s broad scientific program seeks to understand the nature of aging and to extend the healthy, active years of
life. For more information on research, aging, and health, go to
The NIA is a part of the National Institutes of Health. The NIH is the nation's medical research agency and includes 27
Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting
and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and
rare diseases. For more information about NIH and its programs, visit
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