Just eat a balanced diet or you'll be fine

>>7964075
But I want optimum results.

>>7964077
Okay, drink a cup of coffee with cream and brown sugar when you feel tired

>>7964079
>coffee

too much is when you have diabetes

>>7964081
What's wrong with coffee? Caffeine is good.

>>7964074

If you're referring to eating sugar, then you don't need any at all.

too much is when you start feeling sick.

if you eat enough candy you should be aware of when this threshold is for your body

i recommend reeses pieces

45-65% of your daily calories should come from carbohydrate, ideally healthy sources of carbohydrate like whole grains, fruits, legumes. It becomes excessive when it displaces other things to the point of frank deficiency

http://fnic.nal.usda.gov/sites/fnic.nal.usda.gov/files/uploads/macronutrients.pdf

Though a bolus of glucose (30-75g) can be useful to acutely boost cognition, eg

http://www.ncbi.nlm.nih.gov/pubmed/16885218
http://www.ncbi.nlm.nih.gov/pubmed/10713296
http://www.ncbi.nlm.nih.gov/pubmed/11512042
http://www.ncbi.nlm.nih.gov/pubmed/26576942
http://www.eufic.org/article/en/artid/Glucose-mental-performance/

this effect becomes more pronounced in disorders implicating impaired brain glucose uptake and utilization like schizophrenia