Helloo... First of all thank you for choosing HCM. Vitamin b12 wont help in reduction of weight but metformin plays a role in weight loss, you have to add an exercise plan such as jogging or going for a brisk walk for 30-45 mins. Coming to diet follow these tips: 1.Drink plenty of water 1.5-2 litres a day 2.Eat small meals evenly spaced throughout the day ( 4-5 meals ) 3.Avoid carbohydrates, sugary and fizzy drinks, fried and processed food. 4.sleep for 6-8 hours a day 5.Have plenty of vegetables rather than meat. Follow the above and you should lose quite a few pounds. Thank you and take care.