What did you do during your last holiday meal? You single-handedly emptied the horn of plenty by eating a flock of turkeys, a small herd of steer, and half of the produce section of the average Whole Foods. The amount of living energy you consumed would make fat Elvis blanch.
You probably tried to alleviate a little of the pressure in your gut by loosening your belt, but your previously flat stomach still pooched out of your jeans like a freshly opened can of Poppin' Fresh dough. The last thing you wanted to do was take another mouthful. But then you were presented with dessert. Miraculously, you found room – plenty of room – for pie.
It turns out there's a scientific reason for this phenomenon, and it's based on a form of evolutionary adaptation known as "Sensory Specific Satiety."
Whether you're familiar with the principle or not, sensory specific satiety is what allows people who know squat about nutrition to eat a relatively balanced diet. In simplest terms, if you eat a large amount of the same food in a single sitting, you'll get sick of it and won't want to eat anymore. However, if some new food is then introduced – one that stimulates different taste buds – you'll usually reawaken the urge to eat.
Evolutionary biologists believe this trait is what allowed us to survive as a species. Pretend for a minute that sensory specific satiety didn't exist. If that was the case, your ancestors might have, for instance, repeatedly feasted on wooly rhinoceros, but as everyone knows, wooly rhinoceroses are hardly a source of complete nutrition.
Without this appetite-governing principle to aid them in their food choices, your ancestors would have eaten their fill of rhino carcass and probably ignored the berries, mushrooms, or pine nuts that might have been near it.
In doing so, they would have missed out on all the nutrients they needed to thrive and ultimately evolve into the supposedly big-brained specimens that we are.
The principle of sensory specific satiety provided a wide spectrum of nutrients, but it also provided and continues to provide a lot of calories.
When lab animals are fed a variety of foods, aka a "cafeteria diet," they rapidly gain weight. All their pants have to be let out. Their wives call them "Captain Neck Fat" behind their furry backs. What happens is that the hypothalamus – where the appetite control center resides – gets bumfuzzled.
Normally, a food activates the specific group of cells that register sweetness, sourness, tartness, saltiness, etc. You eat until the cells, in effect, register fullness and the "hedonic pleasantness" of the food diminishes.
However, when you're turning on all those different cells at the same time, animals eat much more food before they take off the feed bag.
Limited experiments on humans have shown the same results, but you don't need any scientific studies to tell you that – you've experienced it.
Most fitness or nutrition-minded people are already, subconsciously, putting sensory specific satiety to work for them. Their meals generally consist of a few nutrient-dense foods; a serving of meat, a vegetable or two, and maybe an unprocessed grain. You know, the kind of sameness or even blandness that allows sensory specific satiety to kick in.
These meals are not served in courses designed to titillate different taste buds. There are generally no pies in the picture. As such, overeating doesn't occur.
Ironically, it's often the quest for "perfect" nutrition that leads to habitual overeating and the ensuing fatness. You see it all the time in families where the father or mother attempts to provide "well-balanced meals" by bombarding the family with all manner of food courses and food varieties, many of which (e.g., desserts) thwart sensory specific satiety and lead to overeating.
However, people with even a little nutrition knowledge know that we don't have to get all our nutrients in every single meal. Nutrition is far more forgiving than that. We can get some of our nutrients in one meal and others in a meal later in the day or even later in the week.
Even so, it's quite alright to squelch sensory specific satiety every now and then. It's pretty hard to gain any measurable adiposity in a single meal the damage, of course, occurs when you do it over and over again.
- Tara Parker-Pope, "Room for Dessert? It's Science," The New York Times, Tuesday, December 7th, 2021.
- Amy C. Reichelt, et al. "Cafeteria diet impairs expression of sensory-specific satiety and stimulus-outcome learning," Frontiers in Psychology, August 2014.