When the apnea-hypopnea index is positive we generally speak of sleep-disordered breathing (SDB). SBD is a prevalent condition in the US general population that commonly associated with overweight and obesity. Most often problems with weight are caused by metabolism infringements and some eating disorders such as binge eating disorder.
Sleep-disordered breathing and all related diseases (sleep apnea, hypopnea, obesity hyperventilation syndrome, etc.) usually improve when the eating disorders causing overweight and obesity are properly treated. So there is a straight relation between weight loss and improvement in sleep-disordered breathing.