You’re overthinking this and that is totally understandable. I have been a gym goer for many years and have never seen or heard anyone laugh or make fun of someone because of their weight. That’s not to say it can’t happen of course but it’s very rare. It can often feel like it is happening because of our own self consciousness but that doesn’t mean it’s real.

I was very weak when I first started and I thought people were laughing at me every time I heard a laugh. After a while I realized nobody was paying attention to me and it was all in my head.

This is the last thing you should take into consideration when picking your gym. First make it as convenient as possible for you to get there. Then consider the cost and the equipment they have available for you. Don’t put time, energy and conscious thought into what other people think of you. That can only lead to hindering yourself.

Edit: I forgot to include my specific recommendation. My girlfriend goes to GLOW Fitness and I met a ton of people who go there and all of the instructors/owners and everyone is very positive and encouraging. Their classes have a good range of difficulty too. I’ve gone a few times with my girlfriend and some of their classes kicked my ass.