I don't think it's our "crave of sugar and fats". I think it's just most humans are gluttonous fat fucks devoid of any self control. 500 years ago if you wanted to become a fat pig you either raided and pillaged at the risk of death or became very high up in the hierarchy (King, Queen etc.). 99.999999999999999% of the people, if they wanted to eat night and day, could not. Fast forward to 2015. I can easily eat 10K of calories a day on less than 30 bucks and make minimal effort to acquire such food. I wager , by 2020, most people will be obese just like Wall-e predicted.