“I can’t eat just one Beccha!”
This slogan for Lay’s Potato Chips was appealing in mid-20th century America, before the obesity epidemic. Looking back today, critics argue, it foresaw the food industry developing enticing products designed to make us overeat.
The idea is that certain combinations of sugar, salt, and fat make manufactured foods not only delicious but also overly comforting, or what some nutrition experts call “hyperpalatable.” These ultra-processed foods, enriched with chemical additives, can reach a “bliss point” that causes cravings and impulsive eating. In today’s food environment, many of us succumb to these temptations at the expense of our health.
However, as I argue in a new paper in PLoS Medicine, this narrative does not stand up to scrutiny and distracts from the true dietary drivers of obesity.
We tend to think of deliciousness as an inherent quality of food. Cheesecake is delicious, but cauliflower is not. However, the perception of taste is strongly influenced by conditioning and the metabolic status of the body. Do you remember the first time you took a sip of coffee or beer? It probably seemed unpleasant. However, the pleasant biological effects of caffeine and alcohol combine with the taste, and many people learn to enjoy these drinks. Similarly, the same fresh bread and butter tastes better before a meal than after a large meal when blood calorie levels are low.
California considers seal of approval for ultra-unprocessed foods
In fact, there is surprisingly little evidence for the commonly held notion that food that tastes too good causes overeating. An authoritative review by neuroscientists and psychologists concludes that “palatability influences what you eat, but not how much you eat.”
Moreover, this belief goes against common sense. Does the United States lead the world in obesity because its food is so delicious? French and Italian people in particular may be different. And let’s think about the implicit solution. That means we need to require the food industry to produce less palatable products to protect our population from continued weight gain.
Clearly, something about modern industrially processed foods contributes to the spread of diet-related diseases. What if it’s not overly delicious? The answer is hidden in plain sight.
Typical binge-drinkers have common characteristics. That means it’s primarily made up of quickly digested carbohydrates (technically, those with a high glycemic load) that quickly raise blood sugar levels. Popcorn, potato chips, pretzels, french fries, breakfast cereals, candy, and sugary drinks are relatively bland but easy to overdose on. In contrast, foods that are primarily composed of fat (olive oil, butter, avocado) or protein (egg whites, turkey breast, hamburgers without a bun) are less likely to be overeaten.
To investigate how these carbohydrates affect the brain, my collaborators and I gave volunteers two types of milkshakes that were adjusted for calories, nutrients, and sweetness. One contained a fast-digesting carbohydrate (corn syrup). The other is a slow-digesting carbohydrate (cornstarch). After taking the fast-digesting version, my blood sugar levels spiked initially. But four hours later, as temperatures dropped, volunteers reported even more hunger. At the time, functional MRI showed strong activation in the nucleus accumbens, a brain region that mediates reward, desire, and addiction.
This finding suggests that we crave processed carbohydrates not because they taste good, but because of how they affect our metabolism. Calories from these foods don’t stay in your bloodstream for long. The reason we want to eat them is because they quickly raise blood sugar levels. The problem is that this sets the stage for the next cycle of surges and crashes.
Given the inherent negative effects of processed carbohydrates, any legislation or lawsuits restricting all foods currently designated as ultra-processed would be a blow to the food supply.
The definition of ultra-processing reflects a philosophy that idealizes traditional cooking methods and treats modern food processing methods as questionable, regardless of their health effects. Under this system, manufacturers can use unlimited amounts of sugar and refined grain products (traditional ingredients), but not a variety of non-toxic or beneficial ingredients, such as protein concentrates, fiber, flavor extracts, and even carbonation.
Targeting ultra-processed foods makes packaged foods less delicious and appealing, but still potentially fattening.
Ironically, many of the products that now represent ultra-processed foods were developed in response to calls from nutritional scientists and governments to replace dietary fat with carbohydrates, a misguided campaign that did more harm than good. We cannot afford another fundamental restructuring of our food supply based on imprecise interventions and uncertain science.
What is the correct way to define ultra-processed foods?
Focusing instead on processed carbohydrates may provide a more precise and practical solution and attract cooperation rather than opposition from the food industry.
Tasty and high-calorie food doesn’t matter whether it’s home-cooked or packaged. What matters is how long you stay satisfied (feeling full) relative to the calories you burn. If eating low-calorie options leaves you feeling hungry quickly and craving more, a 100-calorie snack or sugary drink is no better for your waistline than a 200-calorie nut.
By targeting the dietary factors of weight gain, rather than misleading notions about food taste and enjoyment, we can have our (low-carb) cake and eat it too.
David S. Ludwig is a professor of pediatrics at Harvard Medical School and the author of Always Hungry? and Always Delicious.
