Are gyms better than Fitness classes for losing weight?This is very subjective but I will try to generalize it to the best I can.
Gyms are wonderful if you are already motivated and ready to put in the work without somebody having to constantly push you (I'm assuming by gym you are referring to just a membership and not personal training)
On the other hand fitness classes are a great way to get you into fitness. Often times I have noticed that when people first start training they lack motivation. They want to see a change but don't necessarily want to put in the work, which is a very normal (unreasonable but normal)
Fitness classes are a great way to get past that stage.
Once you start seeing a difference in yourself you will want to train more and you will want to train harder. At this stage the fitness classes might become too slow paced for you. This is the time to make the switch!
So, like I said there is no one thing better that the other here. Its more about where you stand psychologically in your fitness journey!