If certain experts are to be believed, we are currently facing a crisis the likes of which we have never seen before; we are being faced with a global obesity epidemic.Since 1980, the number of people suffering from obesity has literally more than doubled, with there being 1.4 billion overweight adults, and 500 million who can be considered as obese.As far as children go, the numbers just keep on climbing, with certain countries seeing more than a quarter of their kids suffering from obesity. Long story short, if things keep on going the way they do, then in a few decades most of the world's population will be obese, if of course we even manage to survive that long. In order to fight this great plague it is important what it stems from... just like with any huge problem, there are numerous causes in play here.For starters, we are leading increasingly sedentary lifestyles. Long gone are the days when we ploughed fields twelve hours a day or dug up coal in mines... long gone are the days when most people had to dedicate their working time to physical labor. These days, most people work sitting, or perhaps standing still, and needless to say, there isn't much effort involved in that, at least in a physical sense. The problem however is that even though we reduced our level of activity we kept on increasing how much we ate. As a result, our bodies simply aren't subjected to enough exercise to burn all the excess calories we gain, which leads to a noticeable weight gain. However, a lack of exercising coupled with overeating is not the only source of this problem.