Chunking is one of the most common mishits for beginners who are trying to overcorrect topping or “whiffing” the ball. The main cause of the chunk is swinging/casting the head of the club head down first at the top of their swing, losing their lag and 90-degree angle, down to the ball.
When you release the lag early in your downswing it will result in two harmful outcomes. Firstly, you can “hit it fat” or “chunk it” or you release the club head before the hands causing the clubhead to hit the ground first before the ball.
Secondly, not maintaining the lag causes the swing to lose power and distance by releasing the clubhead early instead of releasing after the ball timed up with your hips and body weight.
CAUSE Releasing the ‘lag’ or clubhead early before the hands.
EFFECT Hitting the ground first and losing power and distance
The number one cause of chunking is allowing the clubhead to pass the hands. If you can imaging impact as the finish line, then we need the clubhead to be the last one to pass the finish line as shown below in Picture B.

In Picture C, my brother Kyle’s lower body guides his arms and club for proper release and lag. When the lower body starts to sway and have lateral movement; early release and chunks are a result of that. maintains his 90-degree lag with his arms and keeps his left thumb up like he is hitchhiking, then the clubhead should slide down the red line.
In Picture D below, you can see that Kyle has lost his 90-degree angle with his arm and has released early causing the club head to break through the red line instead of sliding down it (Picture C).

The lower body guides the arms and club for proper release and lag. When the lower body starts to sway and have lateral movement; early release and chunks are a result of that.