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Energy restriction

307 Yoakum Parkway Suite 1821 Alexandria, VA 22304 E-mail: kostofr{at}onr.navy.mil

Dear Sir:

A recent letter in the Journal (1) examines the current relevance of the lessons to be learned from hunter-gatherer experiences. This letter is one part of a more widespread effort to draw conclusions from the mainly dietary experiences and practices of ancient and traditional cultures and to apply these conclusions to improving present dietary practices.

Rather than examine different cultural dietary practices based on many criteria beyond health considerations (eg, religious, ideologic, addictive, geographic, logistic, economic, and power criteria), a more rational approach to improving present diets would be to examine the fundamental mechanisms of the human engine and its available food supply. I have been conducting a text mining study of the discipline of energy restriction by using information technology techniques previously applied to other technical disciplines (2, 3). The MEDLINE (National Library of Medicine, Bethesda, MD) and SCIENCE CITATION INDEX (Institute for Scientific Information, Philadelphia) databases serve as my primary sources for identifying reference articles. The focus of the study is laboratory and clinical nonpathologic experiences with energy restriction for health improvement, applied to all living species. Excluded are starvation, disease-caused energy restriction (eg, cancer), surgically driven energy restriction (gastric bypass and banding), and psychologically driven energy restriction (bulemia and anorexia). The preliminary conclusions of my analysis of thousands of research and clinical articles are as follows:

1. Energy restriction in species with short life spans, mainly rodents, increases the mean and maximal life span substantially (4). In parallel, some of these studies show how the degenerative diseases that contribute to reduced longevity or to aging are eliminated or ameliorated with energy restriction (4, 5).
   
2. Highly controlled laboratory studies are underway to ascertain whether similar benefits of energy restriction apply to larger and longer-lived species, such as nonhuman primates (6, 7). Although more than a decade will be required to observe changes in maximal life span, preliminary results show that the median life span of one group of energy-restricted monkeys is already exceeding that of ad libitum–fed monkeys (7). In addition, emerging data from primate studies strongly suggest that the physiologic responses to energy restriction in monkeys will parallel the extensive findings reported in rodents (6).
   
3. Parallel, long-term, controlled studies of humans have not been done and, even if started today, would require many decades to obtain definitive quantitative results. Short-term studies of humans have been performed with the use of very-low-energy or hypoenergy diets and fasting. Positive changes in biomarkers for several physical ailments, such as cardiovascular disease, hypertension, and diabetes (and obesity itself), have been observed (8, 9).
   

Thus, the hard laboratory and clinical evidence shows that energy restriction is associated with longevity and good health in small species, may provide such benefits to nonhuman primates, and may offer the potential to provide such benefits to humans. As far as I can determine, controlled energy restriction is the only regimen that has been shown in the laboratory to increase life span and therefore may be the foundational requirement for proper diet. In particular for humans, how can we make optimal use of these findings before conclusive laboratory and clinical data are obtained?

Controlled laboratory and clinical studies of energy restriction are not the only source of useful information. Another completely ignored source of information is the study of the food available to humans and its intrinsic effect on human structure. From an engineering perspective, human beings were designed to be lean, to minimize loads on the body's weight-bearing structures and joints and to minimize circulation restrictions. The fundamental fuel available to humans is designed to ensure that humans remain lean. Unprocessed human food is mainly high in bulk and low in energy. In addition, it has high ratios of fiber, vitamins, and minerals to energy, thereby satisfying nutritional as well as leanness requirements. The human body has built-in governors to limit the amount of unprocessed food that can be ingested, starting with taste limitations for high volumes of unprocessed food. All food processing has the effect of artificially stimulating the appetite, allowing more food to be ingested than the body's natural governors would allow, and thereby increasing energy consumption beyond functional requirements. Most low-energy and low-volume processed-food diets do not work in the long term, because the low amounts of processed food lead to a stimulated appetite and unnatural feelings of food deprivation.

Obesity is the prime result of poor dietary practices and is a biomarker for myriad serious diseases. To reduce obesity over the long term, substances and processes that artificially stimulate appetite must be eliminated from the diet. The whole idea of "tasty" food needs to be modified. The terminology also needs to be changed: energy restriction is nature's design for all species; there is nothing restrictive about it.

REFERENCES

1. Walker ARP. Are health and ill-health lessons from hunter-gatherers currently relevant? Am J Clin Nutr 2001;73:353–4 (letter).[Free Full Text]
2. Kostoff RN, Braun T, Schubert A, Toothman DR, Humenik JA. Fullerene data mining using bibliometrics and database tomography. J Chem Inf Comput Sci 2000;40:19–39.[Medline]
3. Kostoff RN, DeMarco RA. Science and technology text mining. Anal Chem 2001;73:370–8A.
4. Masoro EJ. Caloric restriction and aging: an update. Exp Gerontol 2000;35:299–305.[Medline]
5. Eckles-Smith K, Clayton D, Bickford P, Browning MD. Caloric restriction prevents age-related deficits in LTP and in NMDA receptor expression. Mol Brain Res 2000;78:154–62.[Medline]
6. Lane MA, Ingram DK, Roth GS. Nutritional modulation of aging in nonhuman primates. J Nutr Health Aging 1999;3:69–76.[Medline]
7. Hansen BC, Bodkin NL, Ortmeyer HK. Caloric restriction in nonhuman primates: mechanisms of reduced morbidity and mortality. Toxicol Sci 1999;52:56–60.[Abstract/Free Full Text]
8. Capstick F, Brooks BA, Burns CM, Zilkens RR, Steinbeck KS, Yue DK. Very low calorie diet (VLCD): a useful alternative in the treatment of the obese NIDDM patient. Diabetes Res Clin Pract 1997; 36:105–11.[Medline]
9. Pekkarinen T, Takala I, Mustajoki P. Weight loss with very-low-calorie diet and cardiovascular risk factors in moderately obese women: one-year follow-up study including ambulatory blood pressure monitoring. Int J Obes Relat Metab Disord 1998;22:661–6.[Medline]

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