Yes, sugar addition is very real. Here's the cliff notes of the mechanism> sugar gets absorbed into the blood stream as glucose and acts on the mu receptors (opiod receptors) in the ventral tegmental area of the midbrain. The opiod neurons connected to the mu receptors are heavily involved in reinforcing and rewarding behavior, and send signals the nucleus accumbens in the cerebral cortex. Quite literally, this reverberating pathway reinforces your craving/desire/need for sugar and sugar containing foods have a higher food reward than an isocaloric food from any other source. This is the same pathway involved in recreational drugs (cocaine, MDMA, etc) but caffeine has more to do with ryanodine and calcium channels with respect to withdrawl.
If you went cold turkey with no sugar for 20-30 days, this would stop. I don't think you need to stop having cookies or chocolate, I just think you need a lower food reward and the only way you can do that is by resetting your palate and brain by abstaining for a while.