Heavy weights v light weights and lots of reps?????

Hi all,
Help please.
What is best for weights loss? A few reps with heavy weights or lots of reps with medium weights (says around the 30/40 Kg mark)?
I know any mussel is better than none but I am very limited to what I can get access to. Or should I just do lots of running and forget the weights if cannot “lift heavy” e.g. 100 Kgs and above I’m wasting my time. :sad:
When I say lots of reps I'm talking 30 plus.
Any and all answers welcome. :laugh:
Not sure which board to post on so that is why it is on more than this one.:blushing: