m 28 years old 170 cm (5'7") 60 kg. i am a student.i do 30 minute workout thrice a week. my thyroid levels are normal.i guess i have an ectomorph built but a endomprph tummy(it is bit huge for my size). i am losing weight without any strain and dieting but my tummy still big. i was lean till 21 years and then i gained few pounds and had a constant weight for 6 years. now suddenly i stated losing weight and i am back to skinny version. i want to know how to gain more weight and stop losing weight. i dont have any other symptoms.