text: is the b-12 shot effective for losing weight?   no, i don't think so.  i give myself a b-12 shot once a month, but that is because my body can't absorb b-12 from the food i eat.  my doctor says that it really has nothing to do with helping you lose weight.  you only need a b-12 shot if your body doesn't absorb it, and this often happens to women as they age.  vitamin b-12 deficiency is quite serious over time, so if you need it you should get it.    however, if you need it, you may feel better once you start getting enough b-12, which would then help you lose weight.