“Betcha can’t eat just one!”
This well-known slogan from Lay’s potato chips was charming in mid-20th-century America, a time before the obesity crisis emerged. In hindsight, this phrase hinted at a food industry that, critics argue, crafts irresistible products aimed at encouraging overeating.
According to some, the specific blends of sugar, salt, and fat in industrial foods make them not only tasty but excessively enjoyable, or “hyperpalatable,” as described by nutrition experts. Boosted by chemical additives, these ultra-processed foods can reach a “bliss point” that fuels cravings and compulsive consumption. In today’s food landscape, many fall prey to these temptations, compromising their health.
However, this perspective does not hold up under scrutiny and diverts attention from the true dietary causes of obesity, as I discuss in my recent paper in PLoS Medicine.
We often perceive tastiness as an intrinsic quality of food: Cheesecake is delightful, while cauliflower is not. Yet, tastiness is significantly shaped by conditioning and our internal metabolic state. Recall your initial taste of coffee or beer; it likely seemed bitter. Over time, however, many grow to appreciate these drinks as the favorable effects of caffeine and alcohol combine with their flavors. Likewise, freshly baked bread and butter taste more satisfying before a substantial meal, when calorie levels in the blood are low, than after.
Surprisingly, there is scant evidence supporting the widely accepted idea that overly tasty foods lead to overeating. An authoritative review by neuroscientists and psychologists concluded that while “palatability affects what one eats,” it does not determine “how much one eats.”
Moreover, this belief defies logic. Is the U.S. at the forefront of obesity because of its exceptionally delicious cuisine? Countries like France and Italy might disagree. Consider the proposed solution: should we mandate the food industry to create less flavorful products to protect the public from continuous weight gain?
It is clear that something within modern processed foods contributes to the rise of diet-related illnesses. If not excessive tastiness, then what? The answer is evident.
Foods commonly associated with binge eating share a characteristic: they are primarily made up of fast-digesting carbohydrates that quickly elevate blood sugar (those with a high glycemic load). Items like popcorn, potato chips, pretzels, fries, breakfast cereals, candy, and sugary drinks are relatively bland, yet are notably easy to overconsume. In contrast, foods rich in fat (such as olive oil, butter, avocado) or protein (like egg whites, turkey breast, hamburger without the bun) are much harder to binge eat.
To investigate how these carbohydrates impact the brain, my collaborators and I conducted a study where volunteers consumed two milkshakes matched for calories, nutrients, and sweetness. One shake contained fast-digesting carbohydrate (corn syrup), while the other had slow-digesting carbohydrate (corn starch). Following the fast-digesting shake, blood sugar initially spiked. However, four hours later, it dropped, and participants reported increased hunger. During this time, functional MRI revealed strong activation of the nucleus accumbens, a brain area associated with reward, cravings, and addiction.
This suggests that the appeal of processed carbohydrates lies not in their taste, but in their metabolic effects. The calories from these foods don’t linger in the bloodstream. We crave them because they quickly elevate blood sugar, setting the stage for the next surge-and-crash cycle.
Given the specific negative impact of processed carbohydrates, legislation or litigation aimed at restricting all foods labeled as ultra-processed would severely affect the food supply.
The definition of ultra-processing is rooted in a philosophy that idealizes traditional culinary methods and regards modern processing techniques with suspicion, regardless of their health implications. Under this framework, manufacturers can use limitless amounts of sugar and refined grains — traditional ingredients — but not a range of benign or beneficial ingredients like protein concentrates, fiber, flavor extracts, or even carbonation.
Focusing solely on ultra-processed foods would make packaged goods less appealing without reducing their fattening potential.
Ironically, many products now seen as ultra-processed were developed in response to demands from nutrition scientists and the government to replace dietary fat with carbohydrates, a flawed initiative that caused more harm than good. We cannot afford another comprehensive overhaul of the food supply based on vague interventions and uncertain science.
Instead, concentrating on processed carbohydrates offers a more accurate and practical solution that could encourage cooperation with, rather than opposition from, the food industry.
The issue isn’t delicious, calorie-dense food, whether home-cooked or packaged. What truly matters is how long we remain satisfied (satiety) in relation to the calories we consume. A 100-calorie snack or sugary drink isn’t more beneficial for our waistline than 200 calories from nuts if the lower-calorie option leaves us hungry and craving more shortly afterward.
By addressing the dietary factors contributing to weight gain, rather than misconceptions about food palatability and enjoyment, we can enjoy our (low-carb) cake and eat it too.
David S. Ludwig is a professor of pediatrics at Harvard Medical School and author of “Always Hungry?” and “Always Delicious.”
