Without enough B12, you may experience fatigue, brain fog, low mood, or even anemia
In pernicious anemia, parenteral vitamin B12 is needed long term, and monthly injections may be required for life
Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism
That's when they finally realize that the problem isn't as simple as that
Its important to note that B12 injections are only recommended for patients with a confirmed deficiency