The workout itself is only about 5 %. So why train at all, if you want to lose weight?
Because strength training changes the biggest share. More muscle means a higher resting metabolism, which is a faster metabolism, and it runs every day, including the days you do not train. You are not losing weight on the three days you were in the gym, you are losing it on all seven.
The second biggest share is everyday movement: walking, stairs, standing. That is why a brutal session does not always pay off. If it puts you on the sofa afterwards, you hand back at one end what you gained at the other.
And cardio? It stays important, just not mainly for losing weight. It is there for your heart, your circulation and your endurance, and those are good reasons on their own. For losing weight it helps, but the work is done by the strength training.