If I were you, I'd setup a survey to collect info on the reason why the prospect wants to lose weight. Take the top 3 to 5 answers and turn them into mini-niches. I'd tailor an individual lander around each mini-niche. Split test a short vs a long letter (several CTA spread throught - top, middle, bottom. However, I wouldn't do it for the purpose of selling but collecting leads. Nurture the leads over time and then hit them with the sale when they are ready.
Also, site rendering time, mobile responsiveness and spellings affects your quality score. You're failing at all three.
