Dr. Sharma gave a humorous talk on Obesity.  Basically once your body has reached a certain weight that is what it aims to stay at.
Most research shows that dieting does not work which leads to this yo-yo effect in weight loss attempts.
 
 
He points out that it is not an individual's fault and they are not "fat and lazy" if they fail to lose weight.
His website will give you a good idea of the topic of the day.