As someone who has lost 22KG in 4 months, calorie deficit of 500-1,000 per day was key for me (via eating less and eating differently).
I helped achieve this via doing more ; I do 10 miles per day of walking (approx 22,000 steps), but that takes 2 1/2 to 3 hours of effort per day to achieve. I used to do 1/3 to 1/2 of that amount of walking previously.
From what I understand, you need to up protein intake to help counter muscle loss and help target the weight loss at your body fat content. If you fail to do this you risk muscle loss and your resting metabolism drops as a result. You risk becoming what I've seen called "skinny fat". That drop in metabolism increases the likelihood of gaining the weight back again (and more) if you stop the calorie deficit. Protein is also more filling and harder for your body to convert into energy, so helps with weight loss and keeping hunger at bay. I eat a lot more chicken, tuna, salmon and eggs now than I did previously. I also take whey protein and collagen powder in skimmed milk once per day to boost my protein intake. I'm trying to target 90g-100g of protein intake per day, but there seems to be a wide range of opinion on how much protein you should target and if it risks damage to your kidneys if you have too much.
I also have started to do weight lifting (at home and not loads) to help preserve (and very slowly gain) strength as I've always been a bit weak and weedy. I'll probably need to join a gym and/or get a Personal Trainer through to gain upper body strength and up my metabolism as I transition from a weight loss focus to a muscle gain focus.
I should add that I'm late 40's and I think that makes losing and maintaining weight loss more difficult than if I were in my 20's.