Obesity is a complex disease for which no single cause or cure exists. You gain weight when you take in more calories than you burn off. But obesity is influenced by many other things, including:
Obesity has a strong genetic component. Offsprings of obese parents are much more likely to become obese than offsprings of lean parents.
These highly engineered junk foods cause powerful stimulation of the reward centers in our brains
Addiction is a complex issue with a biological basis that can be very difficult to overcome. When you become addicted to something, you lose your freedom of choice and the biochemistry in your brain starts calling the shots for you.