In your case, it is important to know * Your height as per weight * Cause if weakness Certain test are recommended---CBC, Blood Sugar Bone weakness can be due to deficiency if calcium It is imporatant to eat balanced diet rich in protein, carbohydrates, fats, minerals and vitamins.Food like meat, fish, milk products, dry fruits, milk, fruits and vegetables in good quatity should be taken. Increase your daily calorie consumption