hello there. I can understand your problem. firstly, would suggest you to get de-worming done. then get your blood checked for hormonal panel. sometimes certain conditions like hyperthyroidism etc would be causing weight loss or low weight. other dietary advice would be to have high calorie diet. have stuff like groundnuts, dry fruits etc. have food on time, avoid stress. have protein rich diet. avoid alcohol or smoking. and exercise regularly. consult a dietician for a detailed diet plan. regards