Fat golf shots are shots where you have hit the ground before you have hit the golf ball.
This results in a massive loss of club head speed and therefore a big loss in distance. The fat golf shot is being caused by the club head dropping too low before it reaches the golf ball and this can be caused by a number of reasons, such as you leaning over to the right too much as you are swinging down, you not transferring your weight correctly as you swing down, or you releasing the club too early as you swing down. The lowest point for the club head during your golf swing should be as you strike the golf ball so in order to correct this problem shot, no matter what the cause, try the following drill.
Take up your normal golf stance, feet shoulder width apart and usual ball position. Choose a 7 iron so the correct ball position for this club is one ball to the left of the centre of your stance. Take the head cover from your driver, or take your golf towel from your bag and fold it up and place it opposite the outside of your right foot, but on your target line. You want to use your driver head cover or a folded towel so that you have three to four inches of height with these items up from the ground. Take up your golf stance and get a well balanced start position. Hover the club up off the floor so that as you swing the club head away you do not knock the head cover or towel. Swing back over the head cover/towel and make a good backswing.
Without the golf ball, on your downswing work on swinging the club head down so that it clears the head cover/towel and then strikes the ground on the left of this, where the ball would be. Do this slowly at first, without the golf ball, to get a feel for the movement. Once you are swinging down, missing the head cover/towel and striking the floor to the left where the ball would be, you will notice that your body is in a relatively upright spinal position, rather than leaning over to the right and that you are transferring your weight on to your left foot as you have to pull your arms more across your body and to the left to make the correct action.
You will also notice that this drill encourages you to hold the club head as high as your hands until you are in a position to drop it down but clear the head cover/towel on the floor so you are now releasing the club head correctly. You will also notice that you are creating a straight line along your left arm and the club shaft as you now hit the ball and ground, rather than before hitting the ball.
So work on this drill, slowly at first, until you can strike the floor without hitting the head cover/towel. If you find it difficult, move the head cover/towel more to the right and then once you are missing it but striking the ground, gradually move it in a little more until eventually it is opposite the outside of your right foot. This will really sharpen and crisp your contact up and you will no longer hit any fat golf shots.