Im aruna. 23 y old male. my bmi is 14.9, what should i do?

Below: As you are aware, the BMI is a calculation derived from your height and weight. To raise the BMI, either gain weight or get shorter.

Diet and exercise: The key to losing weight is not a temporary diet but permanent changes. Sugars and simple carbs from grains esp. cause weight gain. I like Dr. Furhman's diet: http://tinyurl.com/ktampgg Dr. Weil has useful info: http://tinyurl.com/m8avwzh - see his "discuss that" link in his article. Also see https://authoritynutrition.com/weight-loss/ for many useful articles. Exercise is also important.