I speak from the perspective of a recovering anorexic.
You need to be in a calorie deficit of at least 500. So, eat no more than 1200 calories a day (use a calorie deficit calculator online to work yours out accuracy and safely). 1200 calories is fine for most women. I’m not encouraging disordered eating - I was eating about 400 calories a day with 3 hours of exercise a day, which is a terrible idea!
Tips:
Beware of hidden calories - oil, milk, juice, meat/salmon, dried fruit, olives, avocado, pitta, hummus, cheese.
Sit down and google the calories in things, so that you get familiar with what you have in the house and what you’re eating. A lot of seemingly healthy food is highly calorific.
Do not eat - cakes, biscuits, bread, mayo, alcohol.
Throw away everything you have in the cupboards/fridge and start again.
Buy only - veg, fruit, eggs, whole grains, fish, eggs, lean meat, 1 calorie oil spray, spices/chillis/low calorie salad dressing/ salsa.
Portion up the meat and fish, and freeze it, so you’re not eating more than 100g a day, if any.
Have a few vegan days a week.
I felt like I was still eating a full meal, I would have a big bowl of food, but it would be about 300 calories because it was just low calorie veg, (peppers, celery, spinach, tinned tomatoes, carrots, courgettes, onions, mushrooms) put in the oven or fried with lots of spices, so it was really tasty. I would cook for my family and they didn’t realise that my meal was different to theirs, just by excluding meat, and rice/pasta/bread. For example, I’d use an iceberg lettuce leaf as a wrap for a tortilla, instead.
I’d also maintain such a low diet by having a black coffee and an apple for lunch, and breakfast. Absolutely terrible diet, and I’m glad to be on the mend.
A calorie deficit will cause weight loss. BUT it will not lead to better health, or fitness, without exercise.
If you lose 2lb a week, you’ll lose 3 stone by mid July.