Create eBook in Fitness Nutrition, and Sleep (Rest/Recovery)

I am looking for a professional ghostwriter specialized in Fitness, Nutrition, and Sleep (Rest/Recovery). I am building a wellness app (RNF) that clients can access for a monthly subscription. I will personally be building the different fitness programs but I would like to offer an eBook on Nutrition and an eBook in the science of sleeping as part of the value proposition of the wellness membership.