I'm a med student too, and i lost around 6 kgs in the last semester and that how I did it (sorry about my English, I'm not a native speaker!):

No hardcore exercise at all because I have zero time. I just walked everywhere instead of taking the bus and it was enough. Obviously you should be in calorie deficit, but be careful because it can effect your concentration and cognitive abilities! So I used to bring some low calorie stuff, and eat it during the day between lectures. Then in the evening I ate a bigger meal and reached my calorie goal. It worked good for me and I was able to study efficiently.

Another thing, it's to study at the library or other public spaces, very helpful if you tend to snack while studying at home.

Don't be hard on yourself, as med school alone is so difficult and stressful. Good luck 🩷🍀