Vitamin B12 is generally related to aiding weight loss and a number of weight loss clinics advise taking this supplement, however they may not always explain the side effects of taking such supplements. There are not a vast amount of side effects; however, weight loss clinics may not provide all the relative information so make sure you consult a doctor.
As well as talking to a medical professional you should look through studies that have focused on the effects of vitamin B12 and how it relates to weight loss. Many studies have been carried out over the last 10 years however; the most recent study in 2008 was published in the Journal of Applied Sciences. The results indicated that low vitamin B levels in men correlated with high levels of weight gain; however, no study has proven that B12 supplements assist in weight loss.