When trying to drop body fat the importance of trying to diet on as many calories as possible cannot be underestimated. In my experience dropping calories too low too early makes it a lot harder further down the line, increasing your chances of hitting a plateau and ultimately falling off the wagon.
The main reason it is harder at the end is because you don’t have much room to play with calories. There becomes a point when you simply can’t drop calories any lower. If for example someone drops from 1800 calories to 1300 calories once they stop dropping body fat there isn’t many more calories to drop as they are already very low. In some cases you may have to drop as low as 1300 calories but that should be nearer the end of your fat loss phase as opposed to the beginning.
We also need to look at the sustainability of such a drop in calories. If you are constantly hungry from the start of your diet how likely are you to stick to this diet? Being unable to sustain a diet is the number one reason many people don’t succeed when they are dieting. If from day 1 it becomes apparent to you that you cannot eat foods you enjoy you will not stick to that diet which is completely counter productive.
Another reason why I am strongly against big drops in calories is because it increases your chances of losing muscle mass. Retaining muscle mass should be high on your list of priorities when dropping fat and you should be ensuring you are doing everything you can to achieve this. How much muscle you are able to retain after a fatness phase is going to make a huge impact on how your physique looks at the end. If you are finding drops in your strength fairly early into your diet this is a good way to tell if you are losing muscle mass.
My advice would be to slowly drop calories and slowly increase cardio. Make a small change to your calories, wait a week or 2, see what happens. If you are dropping weight/fat or clothes are fitting better then keep calories where they are. When you plateau make another small change, assess and see.
This approach will make your diet more sustainable and you will look better at the end. It may take longer than you would like or than the friend who is crash dieting but I can assure you in the end not only will you look better but you are more likely to maintain your physique unlike your friend.
The sustainable approach usually teaches you good habits that you tend to keep while the crash dieter cannot sustain their diet, as I mentioned before. In this game slow and steady always wins the race.