WHY IT’S HARD TO STOP EATING EVEN WHEN FULL
ALL FOODS are not created equal. Most are palatable, or tasty to eat, which is helpful because we need to eat to survive. For example, a fresh apple is palatable to most people and provides vital nutrients and calories.
But certain foods, such as pizza, potato chips and chocolate chip cookies, are almost irresistible. They’re always in demand, and they’re easy to keep eating even when we are full.
In these foods, a synergy between key ingredients can create an artificially enhanced palatability experience that is greater than any key ingredient would produce alone. Researchers call this hyper-palatability. Eaters call it delicious.
Initial studies suggest that foods with two or more key ingredients linked to palatability – sugar, salt, fat or carbohydrates – can activate brain-reward neurocircuits similarly to drugs like cocaine or opioids. They may also be able to bypass mechanisms in our bodies that make us feel full and tell us to stop eating.
Our research focuses on rewarding foods, addictive behaviours and obesity. We recently published a study with nutritional scientist Debra Sullivan that identifies three clusters of key ingredients that can make foods hyperpalatable. Using those definitions, we estimated that nearly two-thirds of foods widely consumed in the US fall into at least one of those three groups.
Foods that are highly rewarding, easily accessible and cheap are everywhere. Unsurprisingly, eating them has been associated with obesity.
Documentaries in the past 15-20 years have reported that food companies have developed formulas to make palatable foods so enticing. However, manufacturers typically guard their recipes as trade secrets, so academic scientists can’t study them.
Instead, researchers have used descriptive definitions to capture what makes some foods hyper-palatable.
For example, in his 2012 book Your Food Is Fooling You: How Your Brain Is Hijacked by Sugar, Fat, and Salt, David Kessler, former commissioner of the US Food and Drug Administration, wrote: “What are these foods? Some are sweetened drinks, chips, cookies, candy, and other snack foods. Then, of course, there are fast food meals – fried chicken, pizza, burgers, and fries.”
But these definitions are not standardised, so it is hard to compare results across studies. And they fail to identify the relevant ingredients. Our study sought to establish a quantitative definition of hyper-palatable foods and then use it to determine how prevalent these foods are in the US.
We applied our definition to the US Department of Agriculture’s Food and Nutrient Database for Dietary Studies. This contained 7757 food items.
Over 60% met our criteria for hyper-palatability: 70% were in the fat/sodium cluster, including many meats, meat-based dishes, omelettes and cheese dips. Another 25% fell into the fat/simple sugars cluster, which included sweets and desserts, but also foods such as glazed carrots and other vegetables cooked with fat and sugar.
People concerned about healthy eating could be advised to consume foods unlikely to be hyper-palatable – items that occur naturally and have few or no additional ingredients, such as fresh fruit. | The Conversation
Synergy between key ingredients can create enhanced palatability