Influenced

Carbs don't make you fat and although those foods aren't overly nutritionally dense, you can still lose weight eating them. Weight loss is about calories, so if you're eating these things in portions that fit your calorie goal you will still lose weight.

However, and this may come across a little harsh, but just because the food is there, doesn't mean you have to eat it. Try thinking of it as their food. If you want to eat more nutritionally dense foods, take some around with you, if you're eating dinner there that's devoid of fruit, veg & protein plan better for breakfast & lunch. You are the only person responsible for what goes in your mouth, take responsibility.

I'd disagree with what previous poster said about speaking to him and his family, they are not responsible for your weight loss and they shouldn't be expected to change their lifestyle because you want to change yours, especially as from the way I read it, you don't live there, you're just hanging out there?

All of the foods you've mentioned above are not inherently bad on their own, they can fit quite easily into a balanced diet in moderation.

It’s very tough to change eating habits when your life is entwined closely with other people. I experienced something similar with my ex boyfriend; I took on his fast food eating habits when we started living together. I honestly almost did the same thing with my current boyfriend. Luckily I went to behavioral therapy and she helped me make small habit changes each week to jump start my healthy journey (more water, breakfast every day, lunch prep, calorie tracking, setting aside time for exercise, etc). But it does take some planning and habit formation (for example, I always bring my workout clothes to my boyfriend’s house the night before I work out. When the morning comes, I change directly into those clothes, drive home, and do a home workout first before breakfast.) Little habit changes you make can be easier to keep up with if you create a cue for yourself to remember the habit.

Is it possible that you can set aside time every weekend to go to your house/apartment to plan out your week of food? You can plan your meals, grocery shop, and cook every Sunday (or whenever you have a consistent day free). Then you can keep small breakfasts and meal prep lunches in their refrigerator for yourself. You can probably still have their dinners as long as you keep your breakfasts and lunches relatively small in portion, and you control your portions of their dinner. (This is just an idea; this kind of eating doesn’t necessarily work for everyone and you know your eating best.)

If boyfriend/his mom/his sister ask you why you are hanging out at their place less, just say that you are starting to focus on meal prep ( you can even say you’re trying to save money, or you’re trying to learn to be a better cook, etc, if you don’t want to talk about weight loss yet).

Yep. Lots of people eat that way.

Do you have a question? I think you've gotten good suggestions above. Fix your own meals, or bring your own food. You can't change other people - just work on your own stuff.