The exact same effect as e.g. psychedelic drugs is of course not given here. It would be too nice to see unicorns and rainbows from a bunch of Gummi Bears.
The effect, which here is comparable to drugs for our brain, refers to our reward system. This is co-responsible for people developing a dependency on things. Almost anything can be addictive. May it be alcohol, cigarettes, amphetamines or Fast- and Junk-Food. Other things like sports, computer games, sex, gambling, etc. can also be addictive. Anything that releases endorphins (happiness hormones).
Especially fat in combination with carbohydrates is an excellent addictive substance when it comes to food. It has been found out that when people eat chips, they release a lot of dopamine, which is a supporting hormone for happiness. That's exactly why, among other things, chocolate is said to make people happy. The University-Hospital of Tuebingen (Germany) explained that a food consisting almost exclusively of fat and carbohydrates, such as french fries, chocolate, Gummi Bears, chips, etc., releases many hormones in our brain.
And here's the comparison to drugs again: The body gets used to this dopamine release and asks for more and/or the next "kick". Therefore larger amounts of food or sweets are necessary to reach the same amount. Sugar and fast food are scientifically proven to be addictive.
And once again I would like to mention at this point, that there is no problem to eat burgers & co. I myself love a really good burger with sweet potato fries. It just depends on how often you eat it.
The more you eat sweets and other snacks, the harder it is to get rid of them. Overweight people in particular are even more dependent on these things. The brain's reward system literally screams for more.
As with drug-, alcohol- or nicotine-withdrawal, addiction must be slowly and continuously eliminated. You can do this by limiting the number of days when fast food is allowed or by determining how often you can eat it per week. Instead of the Coke, choose a juice or mineral water. Not always, only more often the healthy than the unhealthy one.
The best rule is: If you live and eat 80% healthy, you can leave 20 % to do/eat what you want. Enjoy your life! There shouldn't be any prohibitions, just a little customization. If you need help on how to get rid of the sugar and the Cheesburgers, read the article How to loose weight.