<human>: My boyfriend and I have been in a serious relationship for almost a year..

When we first started dating, he was really fit. He was kinda on the skinny side but still had some muscle. He looked totally normal, nothing out of the ordinary. However, over the past four months or so, I've noticed that my boyfriend's body has significantly changed.

I don't really know anything about steroids but it's obvious that something is going on. He had to buy all new shirts recently because his other ones were getting to be too tight. My dad's a gym teacher and said my boyfriend can't get this jacked without steroids. Talk about an awkward situation to be in.

I've never seen my boyfriend do them and he's never talked or hinted about it. He works out a lot, eats healthy, so it probably wouldn't be a crazy thing to ask but still, I feel like it's none of my business. But I don't want him to feel like he has to hide anything from me.

What's a good way to approach him about this without making him get defensive?

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: I have no idea if my boyfriend's on steroids but it seems likely. I want to know how to talk to him about it.