those formulas aren't always right. While I was cutting I was eating as low as 1200kcal per day and less than 50g carbs. According to those calculations I was eating at like a 1000kcal deficit lol and I needed something stupid like 2900kcal just for maintance, meaning around 2400kcal for controlled weight loss.
and yet the reality was I didnt loose any noticeable amounts of muscle. I lost 40lbs bodyweight over 6 months and my strength levels were only slightly effected. Less than 10% was lost from my main lifts and I actually made a little strength progress on certain lifts while dieting.
Besides, those calculators and formulas are using the idea that every calorie is equal, which from what I've experienced isnt the case. Do you really think 1000kcal of ice cream will have the same effect on your body as 1000kcal made up of chicken breast and spinnach?
Do you really think eating 2500kcal made up of two macdonalds meals per day will have the same weight loss effect as having 6 smaller meals spread evenly throughout the day made up of chicken, eggs or fish with vegetables and a small serving of complex carbs like brown rice or sweet potato?