There is one way on getting thin without sport. Eat less.
For example, if you are a male of age between 30 to 50 you'll need around 2000 calories so eat 1500 or less. Good luck!
Yeah I forgot to say about eating less. Taking less carbohydrates will also help.
More water before eating can also help but about that product or supplement that he's interested to take, I'd advised him to consult first before taking it. That can ruin his appetite if he's not used to that supplement because it doesn't work for most.
Yeah, drinking water before eating sounds like a good idea, I think you can trick your stomach if you drink some water before eating, you will probably feel full with less food eaten. I don't know if this is working but you can try it.
Yes that's really the trick. I've just watched this idea before and I think it's really effective.
Sometimes our body needs some water to take and our mind thinks that we need to eat but in reality, we just have to fill it with water.