The idea behind Starvation diet

I was reading a book called "The End Of Food" today. The one fact which jumped out at me was that there are probably as many overweight of obese people in the world as starving and malnourished ones. I am overweight, probably not by that much by western standards and not enough to worry about it for my own sake. I have never been very good at diets. I start off thinking that its a good idea for the sake of my health, to look better etc but give up because those reasons seem too facile. I needed another motivation beyond myself. Thinking of people starving, not just abroad but here too, may just be that motivation.