If climbing is a sport that you enjoy and are motivated by and it causes you to change your habits and exercise more, then yes, climbing can be a great way to help you lose weight.
Exercise in general is a great way to help you lose weight, but it really comes down largely to your diet. With that said, if you reduce your calorie intake but are not active at all, the journey is going to be less efficient. So both aspects really go together.
Which brings me to my first point. If climbing motivates you to change your habits, improve your lifestyle, eat healthier, and exercise more, then yes, climbing can very much help you lose weight.
