The main thing we should know: don't eat alot rafinated sugar if you don't know how.
When you do it wrong, you have big spikes of hormones( insulin etc.) and then your sugar level is even lower after your meal( in low period of time), and you want eat again. Also when all chemistry happens, you can't really focus, think critical etc.
You can only eat junk/rafinated food if you eat alot of fiber, or combinated healthy food ( example beans with something , if you eat even alot of sugar/rafinated food/cookies etc. after it , your hormones and sugar spikes will be good ), it's all from Dr,Greger researches, alot of this stuff i felt on myself, food-management really works in life, helps realize the preorities in all life-stuff. Good luck bro