The short answer is yes. In a large survey (NHANES) of the US population of over 9,000 adults, it was found that when divided into four groups (quartiles) based on their vitamin B12 blood levels, the likelihood of being obese was significantly higher in the lower two B12 quartiles than in the highest B12 group. This has been seen in several other studies before, but this information is significant because it is taken from a large sample of subjects in the general population and not restricted to people with diabetes or who are pregnant. There are quite a few theories as to why B12 status is associated with obesity, but those need to be explored further.