Critique analysis of scientific paper (How does calorie restriction Essay

Critique analysis of scientific paper (How does calorie restriction work) - Essay Example Testing biases may have played a role, as controlled subjects may have been overfed to the extent of sickness. Despite knowledge of its effects strongly established, its mechanisms remain unknown due to the complexities from metabolic, neuroendocrine, and apoptotic changes involved. Several theories exist on the mechanism of CR. Classical views by evolutionary biologists shows that aging results from the inability of natural selection to pick out and dispose the undesirable characteristics in a post reproductive stage of life. According to a leading research, aging is caused by oxidative damage to DNA, RNA, lipids and proteins. Such damage is reported to have been reduced in CR animals. Studies conducted on CR in yeast have proven that food deficiency has resulted in an increased life span, as part of a synchronized response. Studies conducted on CR and metabolic changes in mammals show that it consists of two stages. The adaptive stage is one in which the restricted animal adjusts to low levels of glucose intake, and results in a striking loss of protein and carbohydrates followed by fat mass. Consequently, the liver produces ketones that are used in the next phase that is the steady state to meet the brain’s energy requirements. Glucose level in the blood falls and then rises, albeit not to the same degree as the initial level, during the whole process. The neuroendocrine system has been found to play a fundamental role in the aging process, its unique feature being that it affects every tissue of the body. Strong evidence is available from researches on various species of worms for part that hormones play in the process. There are normally low levels of pituitary growth hormone (GH), thyroid stimulating hormone, and other hormones in CR animals. This attests the significant position that neuroendocrine system