I started exercising regularly two months back. I used to go to gym 5-6 times a week and started with basic compound movements and cardio alternately. I had an ankle injury two weeks back and was unable to go to gym. Not that I was bedridden but I just couldn't exercise. During this time, my diet more or less remained the same with respect to macro-nutrients. I went to gym today and measured my weight and surprisingly, I had lost ~1.4 kgs (from 66.4 to 65) over these two weeks. Can anyone explain why this happened? I am quite surprised myself. Is this related to muscle degeneration?
It's more likely to have been a matter of diet. Unless you actually track your food, there's a good chance that you might not have noticed a decrease in food consumption. Add to that variations in water weight and what clothing you're wearing (assuming you don't hit the scale nude) and 1.4 kg could be a reasonable change over two weeks.
That could rather simply be water weight. 1.4 kilos is such a small amount that the weight of your most recent foods and the last time you went to the toilet could cause that sort of fluctuation.
Get back into lifting when you can (do upper body and core) and keep at it, you're doing fine. If you continue to lose alot of weight then you might need to try and adjust how much you're eating.