I've been trying to lose weight for the last month. Only lost about 2-3kg. I would say I am 20kg overweight.

All I've done so far is replace my rice and carbs with vegetables, but of equal volume unless im counting wrongly . Sitting at a desk 9-5.

Estimate calorie intake 1600kcal. (Usually I eat 3k)

Any suggestions?

Is exercise the main thing that I'm lacking (did 5 push ups = sore)

Or is there something else in my diet that I'm doing wrong? In particular, I still eat ALOT but it's mostly vege