The reality is that everyone's metabolism is basically the same, unless they have a parasite or metabolic disorder. If it actually worries you, track your calorie intake exactly for a month or two.

If you're taking in 3k a day and still losing weight, yeah, there's something going on and you should consider asking a doctor.

If your definition of forcing yourself to eat is 1.5k a day you just have a low appetite. Enjoy?