I have heard a few people say that before when they did slimming world they put on weight. This is more than likely due o carb intake! People are thinking I can eat as much pasta, potatoes and rice I like, the truth is you can't! Especially if you don't exercise! If I have toast 1 day on sw I tend to stay away from other carbs that day. If I don't have toast I'll have a jacket potato/rice/pasta for my main, but I follow the sw guidelines of it being part of 1 3rd of my plate, so it's a small portion of pasta. I always exercise every night too.
i would defo just give one a go, sw is a lifestyle change, learning to make the right notices, I'd try that one first and see how you get on. If it isn't for you then try something else, but I would advise you to just watch your carb intake and you may be surprised at the weight loss

good luck with whatever you choose to do
