Research Articles

Ingestion of different nutrients, such as fats vs. sugars, normally produces different effects on physiology, the brain, and behavior.  However, they do share certain neural pathways for reinforcement of behavior including the dopamine system.
When these nutrients are consumed in the form of binges, this can release excessive dopamine that causes compensatory changes that are comparable to the effects of drugs of abuse.
Nicole M. Avena, Pedro Rada, Bartley G. Hoebel, 2008. Sugar vs. Fat Bingeing: Notable Differences in Addictive-like Behaviors; Department of Psychology, Princeton University.

Yale University researchers used functional MRI (fMRI) studies to prove that both lean and obese women who test positive for addictive behavior around food show the exact same pattern of neural activity as a chronic drug abuser: very high levels of anticipation of their drug of choice—in this case, a chocolate milkshake—but very low levels of satisfaction after consuming them.
A. Gearhardt et al., “Neural Correlates of Food Addiction,” Archives of General Psychiatry 68, no. 8 (August 2011):808–16. Published electronically April 4, 2011.

Cyclic binging and food deprivation may produce alterations in opioid receptors, which help perpetuate bingeing behavior. In support, appetite dysfunctions in the form of binge eating and self-starvation can stimulate endogenous opioid activity.
Aravich, P.F., Rieg, T.S., Lauterio, T.J., Doerries, L.E., 1993. Beta-endorphin and dynorphin abnormalities in rats subjected to exercise and restricted feeding; relationship to anorexia nervosa? Brain Research 622, 1-8.

People were 30 to 40-percent more likely to be obese if they had addiction in the family. For women, the chance was 50 percent greater.
R. Grucza et al., “The Emerging Link Between Alcoholism Link and Obesity in the US,” Archives of General Psychiatry 67, no. 12 (2010):1301–8.

Several studies have correlated the rise in the incidence of obesity with an increase in sugar consumption.
Bray et al., 1992; Elliott et al., 2002; Howard and Wylie-Rosett, 2002; Ludwig et al., (2001). N.M. Avena, Rada, Hoebel (2008) Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake. Neuroscience and Biobehavioral Reviews, 31.

Our findings clearly demonstrate that intense sweetness can surpass cocaine reward, even in drug-sensitized and addicted individuals.

We speculate that the addictive potential of the intense sweetness results from an inborn hypersensitivity to sweet taste. In most mammals, including rats and humans, sweet receptors evolved in ancestral environments poor in sugars and are thus not adapted to high concentrations of sweet taste.
The supernormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a super normal reward signal in the brain, with the potential to override self-control mechanisms and thus to lead to addiction.
Citation; Lenoir M, Serre F. Cantin L, Ahmed SH (2007) Intense Sweetness Surpasses Cocaine Reward. PLoS ONE 2(8): e698. doi:10.1371/journal.pone.0000698