Beyond its physiological arguments, The Hunger Code presents a damning critique of the modern food industry, arguing that ultra-processed foods (UPFs) are not merely unhealthy but are often deliberately engineered to be addictive. Fung contends that the addictive nature of these products is a primary driver of the obesity epidemic. This is not a matter of consumers lacking self-control; rather, it is the result of food corporations systematically designing products that bypass the body’s natural satiety mechanisms and hijack the brain’s reward pathways. This process, Fung argues, creates a cycle of craving and overconsumption that mirrors the mechanisms of drug and alcohol dependency.

Fung explains that UPFs achieve their addictive potential by delivering a “supernormal stimulus” to the brain. Natural foods have inherent limits on their palatability, but UPFs are formulated with combinations of sugar, fat, salt, and chemical additives to hit a scientifically determined “bliss point” that maximizes pleasure. This intense sensory experience is an exaggerated version of the reward the brain would get from natural food, making it far more compelling. Compounding this is the speed of delivery. UPFs are stripped of fiber and protein, and their food matrix is broken down to ensure rapid digestion and absorption. This creates a quick, intense “neurotransmitter spike” of dopamine, the brain’s primary feel-good chemical. This rapid high-and-crash cycle is a hallmark of addictive substances, from cocaine to nicotine, and Fung argues that UPFs exploit the very same neural circuitry. He also points out that “UPFs are cheaper, more easily accessible, […] and more socially acceptable than any other addictive substance by a wide, wide margin” (125). This “ubiquity” makes them all the more harmful. Furthermore, their affordability creates a direct correlation between poverty and obesity.

To strengthen its framing of UPFs as addictive, the book draws a direct parallel between the tactics of the ultra-processed food industry and those of Big Tobacco. Fung notes that in the 1980s, major tobacco companies like Philip Morris and R.J. Reynolds acquired food giants such as Kraft, General Foods, and Nabisco. They then applied their well-honed “playbook” for selling an addiction to the food market. This included marketing heavily to children, using cartoon mascots to build lifelong brand loyalty, and engaging in “scientific capture” by funding research designed to downplay the harms of their products and shift blame onto consumers. Fung argues that, just as the tobacco industry knew nicotine was addictive, the food industry understands that products engineered for hyper-palatability drive compulsive consumption and, consequently, greater profits. Fung asserts that “The unfortunate (for you) side effect is that you’ll get fat. The food company doesn’t care. They can always blame you for low willpower. They can always fall back on the Calories In, Calories Out argument” (108). In this way, he implies a complicity between unhelpful government advice on weight management and the industry that manufactures ultra-processed foods.

The book distinguishes clearly between natural foods that “would be recognizable to your great-grandmother” (116) and their ultra-processed counterparts, which are industrial formulations made from cheap substances and chemicals that cannot be found in a home kitchen. These are what food writer Michael Pollan calls “edible food-like substances” (116). A key physical characteristic contributing to their addictive quality is “vanishing caloric density” (106), a phenomenon where foods like cheese puffs or potato chips dissolve so quickly in the mouth that the brain barely registers their consumption, encouraging mindless overeating. By identifying the specific mechanisms of addiction and the corporate strategies behind them, Fung reframes the consumption of UPFs as a meticulously engineered biological trap rather than a conscious dietary choice.