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Two years ago I wrote three articles about obesity. In them I described the basic biochemistry facts of fat use and storage. It was a very simplified view, since I described the functions of only three hormones (insulin, adrenaline and glucagon) involved in energy metabolism. There are a few more whose functions are known and undoubtedly others that remain unknown, but for my purposes those three were and still are enough for you to understand the problem.
As I pointed out before, it is known that a normal man has enough fat reserves so as to be able to live a month without eating. At this point in time nobody knows why this is so, but the late Dr. J. V. Neel proposed a very attractive and convincing hypothesis in 1962. According to this hypothesis, natural selection pressured our ancestors to preserve those genes which Neel called "thrifty genes." Those genes allowed them to better adapt and reproduce in an environment in which they had to constantly look for their meals, since there where no plantations or farms. Among those genes were those that let them have fat reserves to go several days without eating. According to Neel, those genes are a liability for today's sedentary, carbohydrate-fat-eating man. Primitive man did not have the time needed to accumulate excess weight. In the long walks and runs that he had to take to find his food he burned calories. Besides, being a hunter, primitive man was also a prey. He frequently had to run for his life, which promoted the releasing of epinephrine into his blood, which in turn promoted the use of his fat reserves. But, nowadays, it is a completely different story. With the apparition of the automobile and all of our other technological advances, modern man has reduced his physical activity to a minimum. What is worse, his diet is not only based mainly on fat and carbohydrates but in the US, for example, the amount of calories per serving is at least twice as large as needed. The results of a study presented last year at a Experimental Biology conference in San Diego indicate that the larger the meals the more people ate; it could get up to more than 500 and 800 calories per day for women and men, respectively.
The copyright of the article OBESITY REVISITED in Molecular Biology/Medicine is owned by . Permission to republish OBESITY REVISITED in print or online must be granted by the author in writing.
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