Word association. Carbs. First thing that comes to mind. What is it? (Don’t worry, this is a safe place.)
Cutting carbs? Low-carb? Carbs are fattening? It’s time to forget everything you think you know about carbs.
First off, low-carb people are right: low-carb diets cause weight loss. It’s well established that low-carb diets work1,2—at least if “work” means “are usually at least marginally effective for short-term weight loss.” Still, given the anemic results of most weight-loss efforts, this is nothing to sneeze at. Low-carb diets are usually somewhat successful, sometimes smashingly so.
I grant all this. But a certain fallacy has crept from these facts and slithered into millions of minds:
Cutting carbs causes weight loss. Thus, carbs are fattening.
This is patently false.
Where to begin.
Discounting alcohol (who can?), there are only three major calorie sources: fat, protein, and carbs. Protein is not primarily used for energy,3 which basically leaves only two major energy sources: fat and carbs.
Carbs are absolutely ancient. Our evolutionary lineage has been eating carbs on a large scale for at least 60 million years.4 To our knowledge, though, this crippling obesity epidemic is exclusively a very modern problem.
What is the simplest way to prove that carbs are not inherently fattening? I guess it would be to find entire populations of free-living humans who gorge on carbs every day, are otherwise unexceptional, and aren’t the least bit fat. So that’s what I did.
But first, did you know 71% of Americans are overweight?5
(I’ve done the math: that’s over two-thirds.)
The average American diet is almost 50% carbs?6 So we eat an awful lot of carbs. And we’re an awful lot of fat. Coincidence?
Ask the Kitavans. They’re a Melanesian people whose diet was 69% carbs7—mainly from tubers and fruit—when they were studied in the ’90s (an excellent decade). Wait for it…the Kitavans were extremely skinny. The average middle-aged Kitavan man and woman had BMIs of 20 of 18, respectively.8
Were the Kitavans skinny-fat? Did their feathery weights belie some sort of carb-fueled health problems? The evidence suggests a hard no. In Kitava, heart disease and stroke, for example, were virtually nonexistent.9
You really can’t explain the Kitavans away. They ate all the food they wanted. According to the lead scientist studying them, “lack of food is an unknown concept.”10
Nor were they very active. They weren’t sedentary, but their average daily calorie expenditure (for you sticklers) was ~1.7x their basal metabolic rate—which is only “moderately active.”11 There are plenty of obese people more active than this.
So the Kitavans ate tons of carbs every day, weren’t terribly active, and were thin as rails.
And before you can say “genes,” there were two cases of abdominal obesity in Kitava (just two). Both bulging guts belonged to Kitavan men who were actually living in other places at the time of the study (eating a “modern” diet), and were only back in Kitava on a visit.12
This suggests it’s the traditional Kitavan diet—not genes—that’s the secret sauce.
And they’re not alone.
Take the Hadza hunter-gatherers of Tanzania (that’s Africa, according to Google). Similar to the Kitavans, ~68% of the Hadza diet is carbs.13 Remarkably, about 50% of the Hadza diet is sugar—oh, the HUMANITY!—mainly via honey and fruit.
Talk about an atomic fructose bomb—every day, for life. Honey makes up 15% of total Hadza calories—which is almost the exact same portion added sugars take up in the US diet (14.9%).14
And sugar is definitely fattening…right?
Similar to the Kitavans, the average Hadza BMI is just over 20.15
The Hadza walk an average of four to seven miles a day—far more than the typical Westerner. But a fascinating 2012 study found that, adjusted for weight, Hadza people don’t actually burn more calories than the typical Western couch potato.16
How is this possible? While the Hadza burn more calories moving around, it turns out that we Western couch potatoes burn so many more calories at rest—again, adjusted for weight—that it all evens out. According to the scientists,
Hadza hunter-gatherers challenge the view that Western lifestyles result in abnormally low energy expenditure, and that decreased energy expenditure is a primary cause of obesity.17
In other words, the Hadza aren’t lean because they’re “burning off” all these carbs.
And now for my ace in the hole. Enter the Murapin people of Papa New Guinea. The Murapin were farmers and pig-herders studied in the ’60s and ’70s (great years, I’m told). This is not a misprint: the average Murapin diet was 94.6% carbs (mostly from sweet potatoes).18
This amount of carbs is almost sickening. The average Murapin man ate 543 grams of carbs a day—a year-round carbicide. If carbs were the least bit fattening, the Murapins would have been morbidly obese.
At ages 20-29, Murapin men weighed an average of 132 pounds, while women weighed 112 pounds—and unlike us, their weights declined with age.19 Heart disease was rare among the Murapins, and diabetes was nonexistent.20 And Murapin men ate an average of 2300 calories a day,21 so you can’t say they were starving or something (nice try, reader).
There you have it. Three populations who ate cartoon amounts of carbs, were thin as rails, and healthy as horses.
This doesn’t prove that eating lots of carbs makes people thin.
But it does prove that carbs don’t inherently make people fat.
Carbs are not fattening. We saw the sort of proof that burns a theory to the ground and then salts that ground so nothing can ever grow there again.
But we also saw something deeper.
The Murapin weren’t eating “carbs”—they were eating sweet potatoes.
The Hadza weren’t eating “sugar”—they were eating fruit and honey.
The Kitavans weren’t eating “starch”—they were eating tubers.
Natural whole foods like these (the kind we’ve been eating for millions of years) aren’t fattening.
Don’t worry about fat or carbs.
Instead, worry about ingredients lists.
Fat and carbs don’t make us fat. It’s only processed fat (vegetable oil) and processed carbs (white flour and added sugar) in processed foods (foods with more than one ingredient) that inherently lead to overeating and weight gain.
More on that later.
Next time, I’ll go to bat for some babies who got thrown out with the low-carb bathwater.
3. Frayn, Keith. Metabolic Regulation: A Human Perspective. Oxford: Wiley Blackwell, 2010 Kindle File, 7.3, Location 4399 of 9142.
4. Klein, Richard. The Human Career: Human Biological and Cultural Origins. Chicago: University of Chicago Press, 1999.
10. Lindeberg, Staffan. Food and Western Disease: Health and Nutrition from an Evolutionary Perspective. Hoboken: Wiley-Blackwell, 2010. Kindle File, Chapter 4.5, Location 3081.
11. Ibid., Chapter 4.1, Location 2319.
12. Ibid, Chapter 4.5, Location 3102.
18. Trowell, HC. and Burkitt, D.P. Western Diseases: Their Emergence and Prevention. Cambridge: Harvard University Press, 1981. Page 174.
19. Ibid., page 175.
20. Ibid., pages 180-181.
21. Ibid., page 174.