In animal studies, fructose causes the four criteria of addiction: bingeing, withdrawal, craving, and sensitization to other addictive substances (meaning after chronic exposure to sugar, it’s easier to get hooked on another drug). In humans, fructose lights up the reward center in your brain called the nucleus accumbens on MRI; but after repeated exposure, the reward center lights up less and less, so you need more and more to achieve the same effect. Fructose has effects on the reward center similar to alcohol; and just like alcohol, can lead to a "vicious cycle" of consumption and disease.
Elizabeth Weil profiles Lustig:
Maybe someday sugar will replace saturated fat as the villain in our diets. If this happens, Lustig will have succeeded in stealing the public health mantle from Ancel Keys, whose landmark Seven Countries Study pinned heart disease on saturated fat and shaped nutrition guidelines in the United States for more than a quarter century. Yet for all his determination, and confidence, Lustig remains pessimistic.