Hi there.. weight loss could be due to viral infections, gastroenteritis, malabsorption, malnutrition,
thyroid problem(hyperthyroidism), tuberculosis, cancer,depression....
Your
tsh is in the lower limit of normal.. if your symptomatic of hyperthyroidism like excessive sweating, palpitations, heat intolerance, increased appetite yet weight loss, tremors, anxiety, unable to sleep, weakness... then you need to start on anti thyroid medications.. please consult nearby dietician and endocrinologist..