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DIETS, MOLECULES AND OBESITY: PART II

© Juan C. Mendible

In my previous article, I told you that one gains weight by eating more than what our organisms use, in particular, by eating an excess of carbohydrates. Since we are living in a time in which there seems to be a defective gene for everything from heart disease to homosexuality and including beauty, intelligence, mountain climbing and gum disease, it is not surprising that people are looking at genes to find the cause of obesity. Up to now, there are supposedly more than 200 genes related to obesity.

Now, our organisms can be considered as highly successful in the animal world, after all it has remained unchanged for nearly 200,000 years. It is now, in the second half of the last century, that obesity has started to become an epidemic. More than 1.2 billion people worldwide are obese. Are we to believe that 1.2 billion people have defective genes?. I do not think so. So, what is happening?

The car, television and medicine happened. In other words, so-called ¨progress¨ happened. Man evolved faster socially than genetically. Let me explain.

It is known that a normal man has enough fat reserves so as to be able to live a month without eating. Why do you think it is so? Well, at this point in time nobody has the right answer, 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." These 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- and 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 considered prey. He frequently had to run for his life, which released epinephrine into his blood, promoting 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, man has reduced his physical activity to a minimum. Besides, his diet is based mainly on fat and carbohydrates and he is under the constant bombardment, inciting him to eat delicious and fattening plates. And, as I told you in my previous article, since it is hard to lose weigh just by exercising, it is no wonder that man is constantly gaining weight.

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