How about you don't? You probably know jack shít about nutritional, medical science and health, especially considering that you're struggling for ideas and you probably wouldn't know the first thing about reading medical studies or literature and properly analyzing them. You'd surely end up misrepresenting and misinterpreting the science and probably take everything at face value. Which means that you'd probably just end up giving terrible advice, which is a serious thing since you would be toying around with other people's well being and lives, you could cause people serious health issues.
How about you make something like a makeup channel, that seems like something more suited for you. Or heck, maybe even a history channel. That way you'd just have to read a history book, remember what it says and then parrot it back. I think you would have a lot of fun doing that. Plus you won't have to deal with the same kind of responsibility that comes along.