Thats because utilization of vitamin B12 (especially from supplements) depends on levels of other metabolic cofactors and acids
Important Information

INTRODUCTION Obesity is a major public health problem around the world that is linked to severe comorbid disease conditions, physical impairment, high mortality rates, and compromised quality of life.[14] Obesity is characterized by the buildup of excessive body fat and extreme dysregulation in whole-body energy expenditure, glucose, hormone, and lipid homeostasis that typically present as adverse metabolic disorders.[4, 5] Additionally, the physiological, metabolic, and psychological changes that accompany obesity are major factors in the development of type 2 diabetes (T2D), cardiovascular disease (CVD) (e.g., coronary heart disease, dyslipidemia, hypertension),[6, 7] stroke, inflammation, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), osteoarthritis, sleep apnea, and several obesity-linked cancers (e.g., colorectal, breast, kidney, prostate).[6, 8] Lifestyle modifications including diet and exercise may help reverse obesity and improve chronic disease biomarkers (e.g., T2D),[9] but are largely ineffective in achieving sustained weight loss and glycemic control.[10] Pharmacological treatments for obesity exist, but unfortunately most approved anti-obesity drugs have only modest efficacy and/or produce severe adverse effects (e.g., cardiovascular risks, central nervous system effects)

In a time when proactive health care matters more than ever, vitamin B12 stands out as an essential nutrient for long-term vitality
The British Society for Haematology emphasises that treatment should not be delayed whilst awaiting confirmatory test results if clinical suspicion of B12 deficiency is high, particularly when neurological symptoms are present
Supporting Weight Loss Beyond Medication Both AOD 9604 and tirzepatide work best when combined with lifestyle changes: Balanced diet rich in whole foods and low in processed sugars Regular physical activity tailored to your fitness level Adequate hydration and sleep Stress management techniques Medications or peptides are tools, not standalone solutions