Assuming that you are 25 years old, your daily BMR is 1,730 kcal per day.

Right now you are eating less than your BMR which is a big no no.

When you do that, your body will assume that you are in starvation, and it will try to keep the fat as long as possible, using your muscle as fuel instead.

More read on this: https://www.healthline.com/nutrition/starvation-mode#tips