There are a lot of theories out there as to why obesity rates have been increasing in the West over the past forty years.
One of the most convincing and well-vetted was formulated by two scientists — David Raubenheimer and Stephen Simpson — in the early 2000s. Their idea potentially explains why obesity levels have been rising in the past several decades and the simple change people can make to their diet to lose weight.
This theory is known as the “protein leverage hypothesis,” and today we’ll unpack it and explain how to put it to use in your life.
What Cannibalistic Crickets Can Teach Us About the Innate Hunger For Protein
You’ve likely read about plague-level swarms of locusts and crickets. From time to apocalyptic-like time, they march across the landscape, devouring everything in their path.
Here’s something you might not have known: When crickets hit a patch of land that doesn’t have any nice, tasty starches, they’ll start eating their fellow crickets.
Why would a herbivorous insect become cannibalistic?
Dr. Raubenheimer, who’s an entomologist (a scientist who studies insects), decided to explore that question. He discovered that crickets and locusts consume wheat, corn, and cotton because they’re on the hunt for a particular macronutrient.
No, not carbs.
Crickets eat all that starchy food because their bodies hunger for the protein it contains. When there’s plenty of grass and wheat to nosh on, the crickets will just eat that because those food sources have the right blend of carbs, fats, and, most importantly, protein that they need to thrive.
When they hit a patch of land with plant life that doesn’t contain a lot of protein (like you might find in a desert), crickets will start eating each other. Crickets have an innate hunger for protein that will not be stopped.
Raubenheimer and Simpson decided to take a closer look at crickets’ innate drive for protein in the lab.
They found that if you place two bowls in front of crickets, one filled with food that contains a natural balance of carbs, fats, and proteins and the other filled with food modified to be protein-deprived, the crickets will ignore the protein-deficient food and only eat the food that offers them adequate protein.
Raubenheimer and Simpson then researched what would happen if they only gave crickets access to foods that had been manipulated to have varying ratios of carbs, fat, and protein.
What they found is that regardless of the food set before them, crickets seemed to have a target amount of protein — 210 mg a day — they were trying to achieve with their diet, and they would eat until they reached that target. If the food they were given had a higher percentage of carbs but less protein, they’d eat more total calories on the way to achieving their protein target. If they ate food with a higher percentage of protein, they’d eat fewer total calories because they’d reach their protein target sooner.
Raubenheimer and Simpson noticed this phenomenon in other animals like rats, dogs, and cats. Animals will eat food until they reach a certain daily protein target. Once they hit that target, they stop eating.
If you manipulate the food you give to animals so that it’s lower in protein but higher in fat and carbs, they’ll eat more total calories.
If you make the food higher in protein and lower in carbs and fat, they’ll eat fewer total calories.
Here’s a concrete, hypothetical example to explain this idea: Let’s say you give animals pellets of food that each contain 100 calories, but in varying ratios of carbs, fat, and protein. In one type of pellet, 70% of the calories comes from carbs (17.5 grams), 20% comes from fat (~2 grams), and 10% comes from protein (2.5 grams). In the other pellet, 70% of the calories comes from protein (17.5 grams), 20% comes from carbs (5 grams), and 10% comes from fat (~1 gram).
If an animal needs 100 grams of protein a day, and is given the first kind of pellet, it will eat 40 pellets, or 4000 calories a day. If it’s given the second type of pellet, it will eat 6 pellets, or 600 calories a day. The animal given the lower-protein food will eat almost 7X more food to reach its daily protein target.
The idea that protein consumption drives overall calorie consumption is a now-proven phenomenon called “protein leverage.” Protein has a leverage effect on animals’ overall food intake. If you move the protein lever up or down, it will increase or decrease the amount of the other macronutrients an organism will consume.
Raubenheimer and Simpson had a hunch that, just like other animals, humans are impacted by protein leverage too — that we have an innate, specific hunger for protein, and our bodies have a target amount of protein they’re trying to hit each day to maintain health. And lo and behold, we do!
If you manipulate people’s diet so that it’s higher in protein and lower in carbs and fat, they will eat fewer overall calories because they’ll reach their protein goal for the day faster. If you feed people a diet that’s higher in fat and carbs and lower in protein, they’ll eat more overall calories on the way to reaching their protein target.
What that protein target is will vary from individual to individual, depending on age, sex, activity level, and weight. But for most people, it’s around .36 grams of protein per pound of body weight per day.
These observations led Raubenheimer and Simpson to formulate the “protein leverage hypothesis,” which says “that a dominant appetite for protein in conjunction with a decline in the ratio of protein to fat and carbohydrate in the diet drives excess energy intake and could therefore promote the development of obesity.”
Living in a Protein-Diluted Food Environment Is Making Us Fat
While absolute protein intake has stayed stable for the past fifty years, consumption of fat and carbohydrates has increased dramatically.
Why are we eating more carbs and fat?
The protein leverage hypothesis has a potential answer. When energy-dense carbohydrates and fats dilute the proportion of protein in our diet, we’ll consume more food to compensate for the inadequate protein intake. We have to eat more overall to get to our protein target.
For example, to get 20 grams of protein at breakfast, you could eat three eggs, for a total of 225 calories. Or, you could eat two bowls of cereal and milk at 450 calories.
In the modern day, we live in a food environment in which we’re surrounded by ultra-processed foods that are high in carbs and fat but low in protein. To hit our protein target in this low-protein food environment, we must eat many extra calories in carbs and fat. All those extra calories add up and cause people to gain weight.
How to Use the Protein Leverage Hypothesis to Battle the Bulge
We can use the protein leverage hypothesis to our advantage to lose weight.
As protein researcher Dr. Donald Layman shared on the podcast, increasing your protein intake is likely “the most effective way to correct body composition and lose weight.”
Studies show that individuals with a higher protein diet eat fewer calories. That’s partly because protein helps you feel satiated and full. And protein has this effect not only because it doesn’t spike your blood sugar as much as carbs, but also because of the protein leverage dynamic.
When you eat foods higher in protein, you don’t have to eat as much food to hit your protein target. You don’t feel as hungry and have less of a problem overeating. By hitting your protein target sooner, you can stop eating sooner.
So, if you want to lose weight in the low-protein food environment that characterizes the modern world, you’ve got to intentionally prioritize protein in your diet.
When you’re deciding what to eat, make sure protein makes up a significant chunk of your meal or snack. Dr. Layman says that “the first thing you eat at any meal needs to be the protein part. Your first bite needs to be a protein bite. So when they bring out the bread or the chips or while you’re waiting, you can’t eat that until the protein arrives.”
Beware of what Raubenheimer and Simpson call “protein decoys.” When you’re low in protein, your body craves savory foods, which are typically high in protein, to motivate you to hit your protein target. But a lot of processed foods these days, like BBQ chips, offer a savory taste but contain little actual protein. If you satisfy your savory craving with a savory-but-low-protein food, you’ll continue to be hungry as your frustrated body continues to seek to reach its protein target, and you’ll overeat and consume too many calories. When your body hungers for something savory, satisfy that craving with a truly high-protein food, not a fatty carb-bomb masquerading as protein.
All of this doesn’t mean you have to adopt a diet super high in protein. You don’t need to do the carnivore diet and eat nothing but meat and salt. You just need to aim to get at least .36 grams of protein per pound of body weight a day. Going higher may net you better results both in weight loss and muscle building. I’d recommend going up to .8 grams of protein per pound of body weight. As a dedicated weightlifter, I try to eat one gram of protein per pound every day.
Prioritizing protein along with whole, high-fiber foods like oatmeal and vegetables will make you feel fuller for longer and result in you eating fewer calories without having to exercise a lot of willpower. You’ll be better able to eat in moderation, instead of cleaning your plate like an insatiable locust.
For more insights on the role protein plays in weight and health, listen to our podcast with Dr. Don Layman: