It’s worse than that. Situations where something causes no harm to literally anyone are few and far between. Even less often you have a full and clear picture of a situation. Usually it’s a choice between who gets hurt to what extent and based on what you know you just try to minimize the damage. You will get it wrong a lot.
Life is complicated and all we can do is to try our best and hope others will too.
Visually at first it’s going to be mostly weight loss. How much depends on how much caloric deficit you are running - rule of the thumb if you eat 500 kcal less than what you burn per day you will lose about a pound/0.5kg per week. Diet is 80% of success. Your muscle gains will be low while you are losing weight, but your existing muscles will become more visible.
You see yourself every day so it’s going to be hard to spot differences - compare monthly photos.