Sugar Intake and Body Fatness in Non-industrial Cultures

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Around the world, non-industrial cultures following an ancestral diet and lifestyle tend to be lean. When they transition a modern diet and lifestyle, they typically put on body fat and develop the classic "diseases of civilization" such as diabetes and cardiovascular disease.  If we can understand the reasons why this health transition occurs, we will understand why these problems afflict us today.  Research has already identified a number of important factors, but today I'm going to discuss one in particular that has received a lot of attention lately: sugar.

There's an idea currently circulating that sugar is the main reason why healthy traditional cultures end up obese and sick.  It’s easy tofind non-industrial cultures that are lean and don’t eat much sugar, and it’seasy to find industrial cultures that are obese and eat a lot of it.  But many factors are changing simultaneously there.  We could use the same examples to demonstratethat blue jeans and hair gel cause obesity. If sugar is truly the important factor, then cultureswith a high sugar intake, but an otherwise ancestral diet and lifestyle, should also be overweight and sick. Let’s see if that's true. 

Hadza of Tanzania
The Hadza are hunter-gatherers.  Their diet revolves around fruit, wild game,tubers and honey.  According to a recentanalysis, by weight their diet is (1):

• 18-37 percent berries
• 18-31 percent starchy tubers
• 10-35 percent meat
• 7-15 percent baobab fruit
• 1-19 percent honey

Here's a graph of food intake by season from the paper: 

Baobab fruit is largely sugar by calories.  Year-round, 40-60 percent of the Hadza diet comesfrom sugar-rich foods: berries, baobab fruit, and honey.  This is unquestionably a high-sugar diet,sustained year-round throughout life.  The sugar they eat is all unrefined.
So how fat are these people?  In the same study, menand women had an average body fat percentage of 11 and 20 percent, respectively--lean by any standard.  Body mass indexwas 20.2 and 20.4 for men and women, also indicating leanness.  There was not very much variability in bodyfat percentage between people.  I thinkyou’d be hard pressed to find an obese person among the Hadza.  Blood pressure is also low in thispopulation (2).
Kuna of Panama
The Kuna are one of the first non-industrial cultures I wrote about onthis blog back in early 2008.  Many ofthem live on an island chain called the San Blas off the coast of Panama.  Their diet is fairly traditional and centersaround plantains, corn, cassava, kidney beans, coconuts, a variety of fruits, wildgame, seafood, and chocolate.  Theirlifestyle also remains fairly traditional. But this culture has a vice: white sugar, sweetened beverages, and a smallamount of baked goods, which they obtain through trade.  Dr. Norman Hollenberg traveled to the San Blas islands tostudy the diet and health of this population, and published his findings inseveral papers.  Let’s see what he found.
Dr. Hollenberg and colleagues published the most detailedassessment of the Kuna diet in 2006 (3). Data were reported as servings perweek.  Among sweet foods, they ate 25teaspoons of white sugar per week, added to the traditional cocoa beverage thatthey drank multiple times daily.  Theyalso had about four ounces per week of sweet baked goods (donuts and cookies),seven servings (8 oz each) per week of soda or Kool-Aid, and about 14 servingsper week of sweet fruits (not counting the non-sweet fruits they ate such asplantain and pixbae). 
Adding it all up, by my calculations that comes out to approximately 542grams of sugar per week, or 77 grams per day, split between refined andunrefined sugar.  That’s not much lessthan we eat in the US (~100g/d), particularly if you consider that the Kuna aresmall people (avg height 4’11”; avg weight 112 lbs) and eat less total foodthan we do. 
So how fat are the Kuna?  Dr.Hollenberg’s group reported an average body mass index (BMI) of 22.6, suggesting that they tend to be lean. There's not much variability in BMI in this population.  They are also noted for their lifelong lowblood pressure.
What’s The Point?
A high-sugar diet is not sufficient to produce obesity and other disorders of affluence in humans adhering toa mostly traditional diet and lifestyle, particularly if the sugar is coming from unrefined sources such as fresh fruit.  This is consistent with other reports of beneficial weight loss inpeople eating a whole food diet centered around fruit (4).
That being said, I think everyone can agree that added sugar almost certainly plays a role in obesityand disease in affluent societies such as the US.  Added sugars increase the energy density, seductiveness and palatability of foods, favoring fat gain.  In large amounts, refined fructose-containing foods such as added sugar can also promote harmful metabolic changes.  However, controlled diet trials have shown that this applies mostly in the context of excess calorie intake (which, to be fair, is the typical dietary context in the US).

Thebroader point is that added sugar is part of a dietary pattern that also includes added fats, flavorings, refinedand engineered foods in general.  Thispattern includes the fact that foods are easier to obtain than everbefore, often require no work to prepare, and advertising and our cultural milieu encourage overeating.  And that’s not even getting into thedifferences in lifestyle patterns such as physical activity and sleep betweentraditional cultures and our own, which also play an important role.
Most people intuitively recognize the value of studying the diet andhealth of non-industrial cultures.  Althoughwe can never replicate their diet or lifestyle completely, these cultures offerus a template for avoiding obesity and metabolic disease.  One of the things that has bothered me quite a bit overthe years is the tendency to focus on cultures that confirm pre-existing beliefs, and ignore or downplay other cultures that do not.  It's the easiest path, but it only leads to confusion in the end.  I think we can learn a lot from these cultures if we keep an open mind.