Hello and welcome to health care magic I can understand your concern malnourishment could be related to nutritional deficiency, malabsorption or worm infestation and hormonal imbalance it manifests as low weight for height, weakness lethargy i would like further information to help you better your age and sex have you recently lost any weight in my opinion you should consult your GP for baseline investigations like blood for hemoglobin CBC, AEC (absolute eosinophil count), liver function test meanwhile I will suggest you to follow these guidelines have balanced and well cooked food frequent feeding 3 large meals and 3 snacks in between avoid smoking or alcohol ( if you are having it) You can ask your doctor for food supplement like multivitamins Exercise regularly which will improve your appetite as well muscle strength I hope you will find my response informative and helpful please do not hesitate to ask for follow up questions for further clarification Regards