Can we let our appetites drive what we eat?

Yes, we can–if we can get enough protein from real food sources.

A new book, Eat Like the Animals: what nature teaches us about the science of healthy eating, by David Raubenheimer and Stephen Simpson from the University of Sydney, Australia, details the findings of 30 years of research into the ways our appetite guides our food choices. (I confess I haven’t finished the book yet; I ordered it after reading a summary by the authors in New Scientist.)

The short version: we (and other animals) have built-in appetites that drive us to satisfy a primary need for a daily allowance of protein (typically 15% to 20% of total calories), and additional needs for carbohydrates, fats, sodium, and calcium. If the primary need for protein is not met, humans (and other animals) will overeat everything else they can to ensure meeting what our bodies in their genetic wisdom know to be our required amount of protein.

It surprised me to read that the same ideal ratio of protein to carbohydrates shows up over and over—in slime molds, locusts, cockroaches, beetles, spiders, cats and dogs, mink, and primates (human as well as non-human).

It also surprised me to read that between 1961 to 2000, in the US and the UK, our protein consumption decreased from an average of 14% to 12.5%. When we, like the locusts, increase our consumption of foods high in fats and carbohydrates to make up the protein our bodies need, we add up to 13% more calories per day.

The problem of not getting enough protein to support good health is compounded by our usual diet—in the US, more than half of what most people eat comes in the form of ultra-processed foods, and some people eat processed foods almost exclusively. These industrial Franken-foods are typically low in protein and high in fat and cheap carbs (therefor low in fiber) and loaded with salt and sugar. As we eat more of these foods, we have to eat more and more to fulfill the need for protein. Since processed foods are low in fiber, they don’t trigger the sense of fullness we’d get from natural sources of fiber-rich carbohydrates.

To make these cheap foods irresistible, by design, they are flavored with a counterfeit umami taste—the “signature taste of protein.” So our taste buds are fooled into thinking we’re satisfying the body’s need for enough protein to maintain health.

This is a horrible scenario—but let’s not overlook the positive message: our natural appetites, when not being conned by processed foods, really do know what’s best for us, and what we need. But how do we get ourselves back to the point where we can trust those natural appetites? It’s really easy for me to say, “Just don’t eat processed foods,” because I don’t eat processed food very often. I like to cook, and I like to eat what I cook. But it can be a different story for someone who’s grown up with processed foods, who hasn’t grown up loving the flavors and textures of real food—it can be a hard thing to give up.

But we can make a hard thing a bit easier by starting with a plan to make sure we are getting enough healthy protein in the first place. Without that biologically-driven need to get more protein from unreliable sources, it would be much easier to take the next step in a transition away from ultra-processed foods.

For reference, the authors state that our protein requirements vary by age and activity level, between between 15% to 20% of total calories. From age 18 to 20, it’s typically 18%; for age 30, it’s 17%, over 65, it’s 20%. (Okay, it takes math to dial in our specific, personal protein need, but there are calculators online to do the calculation for you—search for a Harris Benedict equation calculator.)

But if that doesn’t make you curious, and you want an easier fix that doesn’t involve complicated math, it probably wouldn’t hurt just to look at the sources of protein in your diet now. Protein is abundant primarily in meat, fish, eggs, dairy, beans and other pulses, nuts and seeds. You could monitor how much protein you eat in a typical fast-food-free day. The internet can be a great source of info, and any nutritional label should help. When you figure out how you satisfy the need for protein first, you’ve taken the first step to better long-term health, even before you tackle changing a habit like eating processed foods.

And, let’s remember the ingredients list—if you’re looking at something with more than about 5 ingredients, or you can’t pronounce what you see—it’s processed food. Think twice before putting it in the cart.

(This post represents my best  understanding of what I’ve read–any mistakes are mine. The book is very readable–I recommend it.)

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