Different mechanisms, different side-effect profiles
Among them, SIRT1 is the most studied for its role in fat metabolism, muscle preservation, and mitochondrial health
Furthermore, health risks, family history, other medications, age, and personal health factors, are also going to dictate the results you are going to see, and how quickly you can expect to see those results
First, the effect is enzymatic and cumulative you are shifting a metabolic set-point over days and weeks, not triggering an acute hormonal event, which is why steady daily exposure matters more than any single large dose
Biweekly B12 shots are often given to athletes or individuals with high-stress lifestyles who burn through nutrients more quickly