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Your gut is telling you what to eat — and you're not listening

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When I was growing up, my parents cooked at home a lot. The food was usually pretty plain and healthy: lots of vegetables and fruits, grilled or sautéed meats, bean soups. My mom and dad generally avoided restaurants. "The food always makes us sick," they'd say, referring to their perception that eating out was usually followed by indigestion and discomfort. (This was before "food coma" and "food hangover" entered the lexicon.)

As a kid, I didn't really understand their problem. I just thought my parents were boring.

This week, I learned there's actually a whole field of study dedicated to the post-meal malaise they were describing: It turns out the scientific term for "food hangover" is "negative post-ingestive feedback" — or the body telling you that you've done it a disservice with the food you just ate.

"Feedback can range along a continuum from satiety (satisfying) to surfeit to malaise including nausea," explained Fred Provenza, a professor emeritus at Utah State University who's spent his life studying, among other things, nutritional wisdom in animals. "Excesses and deficits of nutrients cause malaise, as do excesses of toxins."

Our food is lying to us

I came across the concept in a compelling new book called The Dorito Effect. Journalist Mark Schatzker tracks how divorced we've become from listening to what our bodies are telling us. In nature, flavor and nutrition go hand in hand; for animals, flavors are proxies for nutritional requirements. Research has shown that the same was true for humans — until flavorings and food additives made it harder for us to discern anything about the nutritional value of food.

Today, artificially flavored foods may have the veneer of health, but they're too often nutritionally bankrupt, Schatzker argues, delivering calories and sugar without sating our bodies' needs.

"This is food that’s truly delicious in the moment," he told Vox, "that has a lot of flavor because we put it there, but it doesn't tell the kind of nutritional story that real food does."

In the book, he points to Provenza's research. In one paper, Provenza fleshes out the post-ingestive feedback idea in the animal world:

The sensation of being satisfied to the full (i.e., satiety) occurs when animals ingest adequate kinds and amounts of nutritious foods, and animals acquire preferences (mild to strong) for foods that cause satiety. Unpleasant feelings of physical discomfort (i.e., malaise) are caused by excesses of nutrients and toxins and by nutrient deficits, and animals acquire aversions (mild to strong) to foods that cause malaise. What constitutes excesses and deficits depends on each animal’s morphology, physiology, and nutritional requirements.

From an evolutionary standpoint, he argues, being in touch with this feedback is essential: It tells the animals when they're being poisoned or when they don't have enough of the nutrients they need to make sure their bodies stay healthy. This is very different from saying whether food tastes good; it's the feeling here that counts, and the feeling in nature is tied to the taste.

Artificially flavored foods taste good — but they're slowly killing us

Processed foods today taste really good. But they can make us feel sick in a way overeating blueberries never can, and this is partly because flavor is now divorced from nutritional information, Schatzker argues.

"[Added] flavors make food more delicious than it deserves to be," he told me. "Put that blueberry flavor in sugar water, and suddenly it's a delicious fruit drink that a child can't resist, and he's getting too many calories."

Over the last year, I've been trying to track how I feel after eating, particularly post-restaurant. And now I understand what my parents — and Provenza — have been saying all along: More often than not, the food is delicious. But more often than not, I leave feeling a little more sluggish than when I came in. I've found that listening a little more carefully to my body has changed how I eat — I avoid restaurants more than I used to, and eat simpler foods at home. I feel better for it. Maybe my parents were on to something.

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