It is inconsiderate, but you'll have to do your best to ignore it. I have a bag of M&Ms that I keep in my room for when I start craving sweets (I have a bit of a sweet tooth). I only eat like, two M&Ms a day and that's enough, but I still get people judging me as though I'm devouring the entire bag! They don't know that I barely eat any of them in one sitting, but the still decide that its their place to comment? Not cool.

But whatever. Its just one of those things you have to ignore.

I think I'm going to go kinda/sorta against the crowd here and say Yeees it was kinda inapporpriate, but in context to the specific situation, I would expect a comment like that. For insance, if I just worked out, and then ate a bag of crisps, my mum would be like, what are you doing that for! and I'll moan and groan, but I'll get what she's saying. It would make no sense for me to eat that after I just worked my arse off. I don't think she was telling you what to eat in the general sense, and if you didn't give context to the situation ie. you just said, 'Hey guys, this lady said soandso' then I'd totally be on board for the 'wth, forget her!' comments, but in this case, I think maybe she was just telling you something out of the sheer 'That makes no sense'-ness of the situation. I hope I'm making sense.

thank you everyone for your replies, they've been helpful.

Since I posted this, I've had several more unwanted comments from this lady.

I made a salad the other night (I love salads but hate making them) and the only dressing in the house was bottled, with soybean oil (which I don't believe is healthy) and loads of sugar. So, I made my own with just some olive oil, water, feta cheese, balsamic vinegar, garlic, and lemon juice. After sitting down to eat with my salad of mixed greens, radishes, cucumber, zucchini, grilled chicken breast, and a sprinkling of sunflower seeds, she comes in and looks at my salad and asks what the dressing was. I told her I made it, and then she said "well, if you want to lose weight you should just eat prepared food, then you know what's in it."

I applied some of the advice here and politely told her that what I eat is of no consequence to her and that was the end of that.

The next day, I made a sandwich with some canned salmon and home-made mayonnaise (sans sugar). I don't eat a lot of bread because sometimes it doesn't agree with me and sometimes give me stomach pains. I was sitting down to eat it when she came in. "Why are you eating bread? I thought you said you couldn't eat bread because it hurt you? You shouldn't be eating salmon, you haven't exercised in a few days so you're just going to gain weight again."

I tried again to tell her that it was none of her business.

Now, I just don't eat in front of her and I try to talk to her as little as possible. She's hopefully moving out in a few weeks but in the meantime it's very trying to deal with her intrusive comments about my weight when I've never told her I was trying to lose any or anything like that. >.<

I think at this point I would tell her you don't need the food police, and that she should keep her comments about your dietary choices to herself. That's blunt, but she's being incredibly rude to you and it sounds like you've dropped some hints and it's time to be blunt.