dear user thanks for contact HCM weight loss has many causes that is common in old age as stress and anxiety and psychological problems..also there is pathogenic infection of the intestine that may cause severe diarrhea and lead to loss of body fluids and decrease weight ,,also un healthy food and bad nutrition has arole in that ...some times we examin the patients clinically and do some investigations like fasting blood glucose and liver enzymes and urine and stool culture to role out diabetes or chronic disease or any intestinal infection that may lead to decrease of weight ...important step is to try to have healthy food and avoid stress and if perisitent loss of weight you should do that investigations wish you healthy life