Thanks for the query. As per your clinical history you are 19yrs old lady, who has lost approx 30 lbs of weight in a comparatively moderate span of time regarding which you are worried. You deny any change in dietary habits or excessive activity. I would like to know about your height and BMI and also whether you are experiencing frequent episodes of diarrhea. Your medication history if present would also be helpful. Weight loss may arise due to number of reasons. 1. Worm infestation may lead to malabsorption, where apart from weight loss, one experiences nutritional deficiencies like Iron Deficiency Anemia, Glossitis (inflamed tongue) etc. 2. Hyperthyroidism can lead to weight loss but symptoms like palpitation, excessive sweating may be noted. 3. Diabetes mellitus may be a cause but excessive thirst and hunger with frequent infection are noted. These are just a few causes. I would advise you to watch your diet carefully ( adequate intake of calories). You can get some tests done like thyroid profile, hemoglobin levels, stool for ova/parasites and blood sugar levels. In case there is any abnormality you can consult your doctor, who may advise for some more tests if required. Hope this helps you.