If you are very B12 deficient you will notice an increase in energy and a reduction in symptoms of tingling, numbness, or twitching/zaps within 24 hours
Your current weight, even if higher than your lowest on treatment, is almost certainly lower than it would be without the medication
Association of vitamin B12 with obesity, overweight, insulin resistance and metabolic syndrome, and body fat composition
B12 injections are also used to treat people with malabsorption (gastrointestinal conditions that prevent proper absorption of B12 from the gut), for example, people with atrophic gastritis (stomach inflammation) and intrinsic factor deficiency (pernicious anemia) or those who have undergone surgical procedures such as gastrectomy or small bowel resection (stomach or intestine removed), autoimmune diseases, etc
Elevated levels of NNMT activity is associated with reduced cellular energy expenditure and increased fat storage