Why We Get Fat? It's Not Us, It's Our Selfish Genes

The simple fact that obesity related diseases are the number one killer in America is a sign that our bodies and brains are still many decades behind the times. Think about it this way if our bodies were computers and our brains the operating system we would just rewrite and update the operating system to NOT crave sugar or fattening foods. The reason why most of us love sweets and crave juicy steaks and creamy pasta is that our unconscious brains are still functioning under the assumption that we are living in nomadic environments where food was scarce and often humans died from starvation and malnutrition. Civilizations have evolved much faster than our unconscious brain. We now mostly live in urban environments with many sources of food. If our brains were conscious of this societal evolution, they would just update/reprogram our genes so:

1. We would not crave sweets or fattening foods and only crave healthy foods 
2. We would have much faster metabolisms to burn all the calories we eat since our bodies would not need to save the fat for the days that we could not find food as it was the case in the nomad days

The bottom line is that we have a reward and punishment mechanism in our brains that try to guide us to make decisions in favor of survival of our genetic code hence this mechanism facilitates the production of dopamine and opiates (feel-good chemicals) in the brain every time we engage in reproduction (sex), food consumption and other actions that contribute to our survival and the survival of our genetic code (DNA). This mechanism also is responsible for activating the part of the brain called the amygdala to produce Cortisol (stress/fear chemicals) when we are faced with dangerous situations that could cause us harm and lead to the death of the organism and hence the genetic code.

The question then becomes, what happens when finally our unconscious brain catches up with the times and recognizes that most of us live in societies where food is not scarce and if anything there is too much of it. Then perhaps our appetites will decrease especially for high calorie foods. What would this do to the food industry? What would it do to the fitness industry? Will we still exercise when we have fast metabolisms and do not accumulate any fat even with very minimal activity?