Boyfriend's Bad Hygiene?

I've been with my boyfriend for over eight months now, and I've never really noticed this before as we don't live together and only see each other once during the week and at weekends. The problem is that my boyfriend doesn't seem to like taking showers very often, I have just recently spent 5 days with him and he didn't shower once. I don't really know how to broach the subject or whether to, but I find it quite off-putting the idea of being intimate/close to him when I know it's been several days since he last washed. How do I talk to him about this without him getting upset or offended? Thanks!