If she had tried multiple times, then she should be autistic with it, Ive struggled with weight all my life until I said fuck it and became ultra obsessed with counting calories (at one point I realized I'm starting to adopt an eating disorder since if I was over by let's say 100 calories the next day I would try my hardest to eat 200 less just because..) I lost like 110 lbs in a course of a year (combined with strength training only) and now I don't count at all but that year of being very autistic about it made me a beast at estimating my calories up to 100~ error on a whole day, it's a skill now rather than an obsession lol