I find Wordpress to be the easiest. You create an account, choose a name for your webpage (it will be something like myweightlossblog.wordpress.com) and then you click "New post", write whatever you want, click "Publish"... and you're done. It doesn't require any HTML knowledge or anything like this... it's pretty much wysiwyg (=what you see is what you get). There's nothing you can mess up, so if I were you I'd give it a try. It's also fun to experiment with different blog designs and stuff.
If you decide to do it and have techie questions, I'm happy to help. Here's where you sign up:
WordPress.com
Honestly, I don't think there's anything easier than Wordpress or Blogspot. I've been blogging for a few years but couldn't find anything more basic than these.