Please don't try and exercise away 2000 calories in a day. You may injure yourself through over-exercise, and even if you don't that will leave your body ZERO calories to maintain your organs. Without trying to go the 'tough love' route, that sort of behaviour leads to exercise bulimia, which is NOT a healthy way to lose weight!
You seem quite upset at your recent weight gain. That can make people stew over the negatives and make it hard to get some perspective. Luckily you have us to see the big picture for you
. So let's break it down.
- You said that you previously weighed 47 kilos. That's only just below your recommended BMI range for your height and, depending on your build, may be your natural body weight. Since you haven't said you've had problems with your weight in the past I'll assume that you are normally at 47 kilos when you eat normally and you don't suffer any health problems associated with being underweight. If you have constantly starved yourself to maintain that weight, however, then perhaps you need to reassess your goal weight as it may be too low.
- You know what caused your recent weight gain. Overeating due to stress. In theory, if you tackle the stress you should solve your problem with overeating.
- You are upset that you ate MAINTENANCE calories for one day. That's an overreaction. You may want to lose weight, but maintaining weight for ONE DAY isn't going to sabotage your plans in the long term. If you eat a few less calories for 6 days out of 7 you are still going to lose weight that week.
- Don't starve yourself whatever you do. That will royally stuff up your metabolism and make it harder for you to lose weight. So put that out of your head now!
You haven't said whether it's easy for you to maintain 47kg normally or whether you have always struggled with your weight. My following advice is based on the assumption that 47 kilos is your natural, easy to maintain weight (under ordinary circumstances).
So here it is: Stop beating yourself up. Stop dieting. Work on stress relief and try to go back to you old eating and exercise habits. This may seem crazy, but here's my reasoning: your recent weight gain was due to stress. Now you're putting yourself under more stress to try and lose weight. If your body's natural reaction to stress is to eat then this will simply make you want to eat more. Then you'll just beat yourself up over it more, creating a vicious circle of weight gain. You are still within your healthy BMI range. Your boyfriend probably hasn't noticed a change in your weights. If your body's natural set-point weight is 47 kilos then it will go back to that weight with healthy eating and exercise.
If you're still keen on a structured weight loss program I recommend talking to a health care professional. You are aiming on the low side of your BMI so only a qualified health care professional would be able to tell you if that's safe or not. With knowledge of your weight and medical history they can tell you if you are being realistic to aim so low. If your weight gain is solely due to stress they can recommend the best ways to combat this stress based on your personal needs.