They can indeed help for weight loss, especially since most of them are fat free or pretty much (no cooking oil, no butter, no meat fat if you use veggies only, etc.), and they're loaded with vegetables. They also have the advantage of being slow to eat, that gives your brain the time it needs to send the signal to your stomach you're getting full so you can't overeat really.
Some soups are so thick they can hardly be regarded as some food floating in flavoured water. It really depends on the soup! I like dutch pea soup the most, pretty filling too. It is called snert here