I was 66kg about 8 months ago. iam now 62.5. iam not on diet and and no rigorous exercises. not having any symptoms. iam non alcoholic and non smoker?

May be normal: Have you increased your activity level recently? (like walking a dog 2 times a day) or have you change what you eat at home? If there is a change in your metabolism from stress or recent surgery or if you have altered your normal intake, this weight loss may be expected. More than 10 lbs. Or 4.5 kg loss in a few months is the normal cut off to start looking for troubles.