Elaborate please.
Well first, the goal should never be to "lose weight", it should be to lose fat.
And running (we are talking long distance running not sprinting) is objectively horrible for that.
Now, if we are talking about sprinting, that's a different animal. But that's not what a running club is, it's long distance running.
There are a myriad of reasons why long distance running isn't doing your physique any favors but the biggest one is that it raises cortisol levels significantly which essentially burns muscle while prioritizing storing fat since your body is in a catabolic state rather than anabolic.
Most people would do much better just walking to burn fat, it's the body's most effective fat burning mechanism without raising cortisol levels and works extremely well when paired with heavy resistance training. It's also phenomenal for sucking glucose out of the bloodstream in the absence of insulin via GLUT-4 transporters in the biggest muscles in the body, the legs and glutes.
And that's the other side of the coin...the most effective way to lose fat is to build muscle which is why heavy resistance training should be the goal.
IMO, heavy resistance training and walking with some extra cardio oof you want for like 20 mins will work extremely well for most people.
Combine that with proper nutrition and sleeping properly and they will be good to go from a hormonal standpoint that puts their body in a muscle building, fat burning mode.