What symptoms you notice may depend on your current state.
In general, desirable may be improved cellular energy production. I'm guessing what that looks like for you may depend on where your systemic weaknesses or deficiencies show up and can be alleviated.
Negatives that could arise from supplementing too much of supplements that tend to increase metabolism could be deficiencies in other nutrients that are not being supplied sufficiently to meet increased needs.
Niacinamide tends to increase the demand for carbs. If it increases overall metabolism, it may also increase demand for lots of other nutrients, and potentially increase the risk of something getting out of balance if the diet is not nutrient-rich.
For me, I look out for an increase in concentration and clarity and energy available to do what I need to do as good. Bad from overdose was head ache/migraine, which I might have been getting anyway, but which can be triggered by blood sugar drop worsened by higher dose niacinamide. There may have been something else going on too, but I'd guess that was part of it.
In general, desirable may be improved cellular energy production. I'm guessing what that looks like for you may depend on where your systemic weaknesses or deficiencies show up and can be alleviated.
Negatives that could arise from supplementing too much of supplements that tend to increase metabolism could be deficiencies in other nutrients that are not being supplied sufficiently to meet increased needs.
Niacinamide tends to increase the demand for carbs. If it increases overall metabolism, it may also increase demand for lots of other nutrients, and potentially increase the risk of something getting out of balance if the diet is not nutrient-rich.
For me, I look out for an increase in concentration and clarity and energy available to do what I need to do as good. Bad from overdose was head ache/migraine, which I might have been getting anyway, but which can be triggered by blood sugar drop worsened by higher dose niacinamide. There may have been something else going on too, but I'd guess that was part of it.