Hi, my aunt use to be 68 kg.. She does a bit of modelling so he worked on reducing her weight and within 2 months she lost quite a bit! when we asked, she said all she did was cut down on carbs, so i guess you should try that. it really helped her lose a lot and in quick time too!
having a good diet could help us lose weight but the process could be slower compare to diet with exercise. I guess your aunt is really motivated and follow a strict diet that's why she is is successful in losing weight.
cutting carbs is always a great way to lose weight. The trick is to do in a manner that's sustainable. Its no fun losing 40 pounds, but then finally giving in to the temptation of pasta and pizza - then gaining it all back at once!
That's why exercise is so important, it generally aids your calorie deficit, but then increasing muscle mass will help your metabolism as well.
I'm still learning a lot, but I would imagine that any caloric restriction combined with regular exercise would work. Of course, the details of the nutrition in the calories that you DO eat becomes pretty important.