Pretend I've just eaten 100grams of sugar... what's that going to do to me biologically?

I mean this whole sugar issue…. insulin levels and what not…

I’ve just realised that I’ve spent all day craving cakes and in the end have massively pigged out (and yes in effect have probably consumed about 100 g of sugar!!). I got to thinking about how all of this seemed incredibly out of my control… a real bodily craving and then I realised that I had cereal this morning that was 50% sugar whereas I normally have ham on toast and low fat cheese. This probably sent my body in sugar ups and downs all day right?

I don’t normally feel like this so wondered whether it’s really all down to the sugar?

Furthermore…if this is the case… how much sugar is safe for you to consume, without it sending you into this roller-coaster ride of craving? In what levels? Is it a percentage of the food we eat at one specific time? (i.e. the percentage of sugar in an apple and a bowl of salad would be ok)

Please feel free to correct me if I’m totally wrong about any of this… I really would like a biological explanation to try and make me more aware of what I’m doing to my body…. (I know hormones fit in there somewhere too don’t they… god this is complicated)