The Evidence in Support of Calorie Restriction - Essay Example

?Calorie Restriction Introduction Koubova and Gurante, 2003, p.313 defines calorie restriction as “a dietary regimen low in calories without malnutrition”. Therefore, in calorie restriction though energy giving food intake is minimized to essential requirement, other required important nutrients and vitamins and minerals in adequate quantities are provided for. Interest in the modern era has sprung as a result of evidence from insect and animal studies pointing to increase in life span and beneficial impact on reducing the impact of conditions and diseases associated with the aging processes. Yet, an understanding of calorie restriction among humans is not limited to the modern era, but runs back to earlier historical times in the development of humankind. This understanding stemmed from direct experiences of the early homo-sapiens. Large-animal kills led to abundant food supply and consumption immediately after the kill and a period of fasting or restriction in food consumption after the food from the kill was exhausted. The period of restricted food consumption ended when the next large-animal kill occurred. This cycle of abundant food consumption and restricted food consumption led to the observation that abundant food consumption led to lethargy, while restricted food consumption provided the benefits of heightened alertness. Eating is a pleasurable experience and desisting from eating not an regimen to follow. Yet, at a time when alertness was critical to the hunting of food and protecting the members of the community, restricted food consumption was practiced among hunters and soldiers, so that their alertness was heightened increasing the chances of a successful hunt for the hunters and success in warding of attacks from the enemies in the case of the soldiers (Mehta & Roth, 2009). The next step in the understanding of the benefits from restricted food consumption, prior to modern science, came from the spread of the early religions and the religious practices that called for fasting. Asceticism comprising of hard rigors including fasting became an extreme form of religious practice. Mehta & Roth, 2009, p.29, quoting Robert Thurman, define asceticism as “the impulse in human beings to attempt consciously to improve control over their habitual life processes, with a view to bettering their situation at least in a relative, and, if possible, in an ultimate way”. Remnants of asceticism as a religious practice continue even today among the general populace. Fasting is a continued practice among the followers of several religious faiths in the modern world. For example, the Muslims fast for forty days from sunrise to sunset during Ramadan, while the Christians observe restricted food consumption during the Lenten period. Prior to the development of modern science, it was religion that provided a systematic means for humans to exert control over their human condition. It was also possible through established religions to communicate the observations, insights, and explanations throughout the populace and spanning generations. For instance, Ayurveda, the popular branch of cultural medicine practiced in India is steeped in such religious observations, insights and explanations, a part of it dealing with the quantum and quality of foods consumed Calorie restriction as a part of modern medical science has become more relevant in the modern world because of the abundance of food and the economic capacity to purchase and consume large quantities of food. Overeating and consumption of rich foods has become more the norm in daily life than a part of feasting during festive days of the yesteryears. As a consequence of the poor eating habits conditions and diseases associated with it like obesity and diabetes type 2, high serum cholesterol levels, high blood pressure and cardiovascular disease have become a bane of society. The beneficial impact of calorie restriction as a medical intervention on these conditions and diseases thus become more relevant to modern society than ever before (Delaney & Walford, 2010). Fasting as a discipline was a part of the preparation of hunters and soldiers in earlier human history. However, the practice of fasting in later human history has occurred among people more as a part of their religious practices. Most religions have periods of time during which their followers are associated with a period of time during which fasting is observed. For the Christians it is the Lenten fasting period, while in the case of the Muslims it is Ramadan. Lessons learnt from the benefits of calorie restriction during such religious fasting, could be a path towards calorie restriction as a conscious process towards establishing control over habitual life processes, as a means to improving their health and life spans (Mehta & Roth, 2009). Calorie restriction occurs naturally during the observance of religious fasting. For example, during Ramadan adult healthy Muslims observe fasting from sunrise to sunset and eat and drink only from sunset to sunrise. Evaluation of the effects of calorie restriction during Ramadan fasting on adult healthy males has shown that there is a significant reduction in weight and BMI and serum levels of glucose and cholesterol, though no significant changes in triglyceride serum levels were found (Salehi & Negab, 2007). Method The methodology used for the evaluation of calorie restriction was a literature review. The locally available libraries were the first target of the search for relevant study articles on calorie restriction. Articles found were collected for evaluation for use in the study. The Internet was the next medium through which a search for research articles on calorie restriction was undertaken. The scientific databases of Medline, Pubmed, BioMed and CINAHL were the main targets of the search carried out through the Internet. Search terms employed included “history of calorie restriction“, calorie restriction”, “calorie restriction and life span”, “calorie restriction and aging”, “calorie restriction and diabetes”, “calorie restriction and heart diseases”, “calorie restriction and heart diseases”, “calorie restriction and obesity”, calorie restriction and weight problems”, and “calorie restriction during religious fasting”. Articles found were collected for evaluation for use in the study. The inclusion criterion of study articles was relevant research articles on calorie restriction published not earlier than ten years back. This which meant that a cut off date of research articles published prior to 2001 was established. Research articles on calorie restriction prior to 2001 were excluded from the literature review. Articles selected for the literature review were such that a broad range of aspects of calorie restriction was made possible. Twelve suitable research articles were included for literature review. Results Figure – 1 Figure – 2 Discussion Interest in calorie restriction has shown a steady growth over the last 25 years. In addition in the last decade the growth research on calorie restriction, as an indicator of interest in modern medical science, is the highest. Two reasons may be assigned for this. Many of the life threatening diseases and conditions are associated with over eating, due to the greater availability of food and the means to purchase food. Reduced food consumption is the norm in such diseases and conditions, but acceptable success levels in their management is yet to be achieved. This heightens the interest in calorie restriction as a possible means to revert the consequences of excess calorie consumption. It is also interesting to note that the number of studies conducted into evaluating the effect of each of the conditions and diseases is in relevance to the prevalence of threat posed and hence the interest of the scientific community. Obesity is the bane of modern society and a certain risk factor for many of the life threatening conditions and diseases like diabetes, heart diseases and cancer. The number of studies conducted on the effect of calorie restriction on obesity is the highest at 41%. Reducing the aging processes and extending life span to immortality if possible, has been the dream of humans. Calorie restriction has pointed to delay in aging processes and extension of life span, at leas in insects and small animals. This is reflected in the interest of the scientific community on the effect of calorie restriction on life span extension and aging processes, which in combination stand at 21%. Cancer is the most dreadful disease, with consequences of mortality in certain forms of cancer, irrespective of the stage of the disease when intervention is initiated. The search for an effective means to combat cancer is the Holy Grail for many members of the scientific community, which is mirrored in the 16% studies on calorie restriction being devoted to cancer. Diabetes is condition with risks for several consequences affecting the functioning of many organs and parts of the body that could result in severe morbidity or death. Managing diabetes thus has become important to the medical community, which has resulted in 14% of the studies on calorie restriction being devoted to its effects on diabetes. Heart diseases are another common cause for morbidity and mortality and this has caused 7% of the studies on calorie restriction to be related to heart diseases. Only 1% of the studies on calorie restriction are regarding its effects on neurodegenerative diseases. This could be due to the possibility beneficial effects of calorie restriction on such diseases being a recent development. It is important to note that in spite of several studies into the effects of calorie restriction on several conditions, diseases, life span extension and aging processes, definitive evidence on beneficial effects that could be translated to humans or found for humans is yet to reliably emerge. This deficiency means that calorie restriction will continue to remain a hope than a reality till such time reliable and definite evidence on its value is unearthed. Limitations and Future Work Limitations in the evidence of the beneficial aspects calorie restriction are several. In the first place much of the evidence in support of calorie restriction is derived from studies on insects and small animals. Extrapolating the evidence from these to larger animals and primates and finally to human beings is necessary to establish the benefits of calorie restriction in human beings. In addition, many of these studies suffer from various aspects of methodology deficiencies. While in some cases these deficiencies arise from the short duration of the studies, in other cases the lack of control measures in the study reduces the utility of the findings of the studies. In the future more studies will have to be undertaken removing these methodology deficiencies and provide reliable findings in support of the benefits of calorie restriction. In addition, future studies are necessary to extend the findings of benefits of calorie restriction to human beings by studies on human beings to confirm whether calorie restriction will prove a useful medical intervention in the management of diseases and conditions that result from the aging processes and also with possible life span extension benefits. Literary References Delaney, B. M. & Walford, L. 2010, The Longevity Diet, Perseus Books Group, Philadelphia, PA. Koubova, J. & Gurante, L. 2003, ‘How Does Calorie Restriction Work’, Genes & Development, vol.17, pp.313-321. Mehta, L. H. & Roth, G. S. 2009, ‘Caloric Restriction and Longevity: The Science and the Ascetic Experience’, in Longevity, Regeneration and Optimum Health: Integrating Eastern and Western Perspectives, eds. William C. Bushell, Erin, L. Olivo & Neil, D. Theise, John Wiley & Sons, Malden, MA, pp.28-33. Salehi, M. & Negab, M. 2007, ‘Effects of fasting and a medium calorie balanced diet during the holy month Ramadan on weight, BMI and some blood parameters of overweight males’, Pakistan journal of biological sciences, vol.10, no.6, pp.968-971. Read More