Beyond the allure of your favorite desserts like ice cream, cupcakes and pies, the sugar in just about any food can be addictive. Believe it or not, sugar addiction begins at birth. Think about it -- human breast milk is very sweet, so even as babies we associate sweetness with happiness and satisfaction.
Here's what happens when you consume sugar. When sugar enters the bloodstream, blood sugar levels (obviously) rise. This causes the pancreas to release insulin. The insulin converts this sugar into energy -- a "sugar high." Unfortunately, excess insulin also encourages fat storage. So, the more sugar you eat, the more insulin you produce, and the more likely you are to gain weight.
A Princeton University study found that rats that were fed sugar became anxious when the sugar was removed from their diets. Some of the rats even experienced withdrawal symptoms like chattering teeth and the shakes.