Hello... I think you should know that, to be fit your weight should be according to your height and appropriate to age.....which is known through BMI( body mass index)....BMI is calculated by a persons weight in kilograms divided by height in meters square. Ideally normal value ranges between 18-24.9 and a person is underweight below 18 and overweight above till 30 and 30 above is obese.... As for as your gastritis is concerned-untimely eating habits and eating spicy or oily foods can cause gastritis. Also drinking coffee amd tea frequently while working also aggravates this condition. And you should know that alcohol and smoking also known to cause gastritis. So the main thing I suggest is to stop all this. The most important thing is to follow a healthy diet which should include green leafy vegetables, fruits and berries which are rich in fibre.take fresh fruits instead of taking it in juice form, since the waste formed while making juice consist of fibres which will be beneficial for the gut, so prefer fresh raw fruits. Take lassi,yoghurt,buttermilk, ragi gunji instead of coffee and tea. Avoid smoked meat products. Avoid outside food, prefer only home cooked meal.drink plenty of water. And never skip a meal. Do daily morning brisk walking, yoga and meditation. If you are not satisfied consult a dietician.