It has now been shown with many studies that severe calorie restriction leads to
ID: 80914 • Letter: I
Question
It has now been shown with many studies that severe calorie restriction leads to a longer life-from yeast to mammals. There also many health benefits from regular exercise, including longer life. For two individual humans-Human A has 9% body fat, is 40 years old, and is sedentary. He maintains his low body fat through a calorie-restricted diet (1500 calories/day). Human B has 9% body fat, is 40 years old, and is a marathon runner. He ingests over 3000 calories per day, but maintains 9% body fat by metabolizing excess calories through activity. Human C is the same as B, except she is female, and has a point mutation that severely restricts her ability to smell. Who will live longest? Defend your answer by explaining cell physiology-based data/theory.Explanation / Answer
According to the question given aboveindividula A will longer than B and C. Caloric restriction lowers the secretion of the fat-derived hormone leptin.Caloric restriction also lowers energy expenditure and insulin secretion.Both the physiological factors are linked as both of them are regulated by leptins.Overeating causes obesity,hypertension and diabetes .All these factors reduce the average life span of a body.In one of the studies Four groups of mice were divided according to the diet they were given.
1.Low fat
2.Low fat with calorie restriction
3.High fat
4.High fat with calorie restriction
The researchers(Huiru Tang, Yulan Wang, Yong Liu and colleagues) found that diet restriction is more important than the amount of fat when metabolic outcome is in question.Mice with high calorie intake had disturbed metabolism especially the lipid metabolism ,increased oxidative stress, suppressed glycolysis,increased signs of aeging when compared to those mice whose calories were restricted.Caloric restriction essentially causes a reprogramming of the metabolism.
Overall calorie restriction causes the reduction of normal body temperature which is a response to reduce energy expenditure.Also calorie restriction causses low grade oxidative stree which elicitis a defensive mechanism to reduce aeging.This also improves overall health of the body and induces longevity.Lowering of insulin,insulin like growth factor and growth hormone due to caloric restriction causes the increase in repair mechanism of the cell(autophagy).
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