Shortage of Food

Iam hearing alot of negative news over the possibility of forth coming food shortages. However I can agree to a point when we look at climate change and the droughts we are beginning, it appears to see across the world.
On the other hand, for instance,here  in the UK and I know also in the US, there is a growing concern over obesity and its illnesses brought on from it.

Shortage of Food Why, Look at this?

I am also worried to learn from first hand experience while in a Asda supermarket, I sneaked behind closed doors, "well when you are a investigative journalist, one must do what one must do", any way I found to my astonishment heaps of food from salads, fruit still perfect, but thrown away because it was one day outside the shelf life.
So the poor people don't get a hear say into this food?. So on this point do we really have a global food shortage? or is there more to the point that I need to uncover?