Fat Shots

Hitting a fat shot or 'chunking' is simply hitting the ground before the ball. Many golfers suffer a mild form of chunking without realizing it. Their shots lack distance as well as bite on the green, caused by failure to impart backspin on the ball at impact. Common Causes: Crouching too low at address, jerky, chopping swing, hitting off the right side with no weight shift, faulty leg and hip action, head movement downward or to the right on the downswing, and dropped right shoulder on the downswing.

Fat shots can be caused by hitting off the right side with no weight shift. Fat shots are caused by the club hitting the ground behind the ball.
Stand more erect if you feel you are crouched too much at address.
Downward movement of the head causes the left shoulder to drop, resulting in a 'chunked' shot. Keep your head steady.
Use your lower body to avoid an 'arms only' swing. Lead the downswing with a lateral hip slide towards the target.