Too narrow a niche?

I have been a weight Loss coach to busy moms for about 10 years now, but recently have been getting asked a lot about Keto. I am creating a digital course for women over 40 who want to do Keto in a healthy & sustainable way. Is this too narrow a niche to focus on? I’m the healthiest I’ve been since going Keto and wasn’t a huge fan because of how some promote it…but if done right can be a powerful lifestyle specially for women over 40 who want to lose fat, balance moods and create happy hormones. I’m super passionate about it.