Our metabolism or in other words the biochemical process that transforms the foods we eat into nutrients our bodies can use, fat it can store or waste it can excrete, depends on our body hormones levels (this can be affected by health conditions, stress, lack of sleep, lack of exercise).

Increased bowel movements, eating more, but, still losing weight, can be due to increased levels of thyroid gland hormones (this gland is most important for our metabolism performance), known as hyperthyroidism.
Feeling hotter that others around you, feeling fatigue at the end of the day, but having trouble sleeping, trembling hands, irregular heart beats, hair loss, nervousness, are all symptoms of thyroid gland overproduction.