How is it possible that people with thyroid lose weight?

Standard tips: I assume you mean people with thyroid problems. Essentially, if you are having trouble losing weight and you are doing everything right, and there are problems with your thyroid gland, then you need to get to the problems at their source - which means either remediating nutritional deficiencies (iodine and selenium, specifically), or getting on a precisely controlled/regulated thyroid rx.

If your thyroid: Level is normal, as in someone with an underactive thyroid who is on the correct amount of brand name T4 replacement to keep their levels normal -- they you are no different than anyone else. You can lose one pound by burning up 3500 more calories than you ingest. When your thyroid levels are normal, your thyroid function is normal and your body functions as normally as it can.