In the top, remove the apostrophe before the word obesity. In the second sentence, change the work Hypoxia to Hypopnea—Apnea Hypopnea Index. Might consider rewording to: Although obesity is not a trait of all patients with sleep apnea, there is evidence that a relationship between weight and sleep apnea exists. Changes in weight have been linked to changes in the Apnea Hypopnea Index.
I like to concept, but the “Effects of Weight Change on AHI” might be confusing to some. Especially because feedback is in percentages. Clinically, we would talk about a patient losing xx pounds or having a reduction in AHI of xx events per hour. I do think asking desired weight and then showing the BMI on a scale if the patient reaches a desired weight is interesting.
From @danmobley: