The tiredness is due to the vitamin b12 deficency, but the bloated feeling is likely due to eating irregularly. I hope when you mean supplements you're taking vitamin b12 supplements. You will require antacids to control the gastritis. For the increase in weight you'll need to exercise regularly. These following lifestyle changes may help: - Don't skip meals, you may not feel like eating but in such conditions you should have the reduced amount in frequent intervals(i.e. 3 square meals broken down to 5 or 6 as you can tolerate) and slowly increase as you get better. - Reduce/ Avoid spicy,fried, fatty, sweet, junk and oily food - Avoid/ Limit drinking coffee, tea and carbonated drinks to once a day - Exercise regularly (30-45 mins minimum, do cardio exercises) - Increase daily intake of water to 3 liters - Avoid/Stop smoking and drinking if you have the habit - Reduce stress through methods such as yoga/meditation. - Avoid painkillers as it will increase your gastric problems at this moment. Kindly monitor your vitamin levels in 3 months and have the supplements as directed by your doctor

Vitamin b 12 is a vitamin. It doesn't not increase your calories intake. Vitamin b 12 is found in dairy products and non veg food items. It doesn't lead to weight gain if consumed as supplement