Thoughts on Obesity, Part I

From the US Centers for Disease Control website:

Since the mid-seventies, the prevalence of overweight and obesity has increased sharply for both adults and children. Data from two NHANES surveys show that among adults aged 20�74 years the prevalence of obesity increased from 15.0% (in the 1976�1980 survey) to 32.9% (in the 2003�2004 survey).

In hunter-gatherer and some semi-agricultural societies, obesity is rare. In most, it's nonexistent. Wild animals typically do not accumulate enough fat to interfere with vigorous exercise, and when they do, it's because they're about to hibernate or migrate. Wild animals also tend to have similar amounts of body fat between individuals (at a given age and sex), unlike industrialized humans. This makes me think that obesity is an unnatural effect of our current lifestyle. Whatever the cause, it's getting progressively more common.

According to certain nutrition experts, we know exactly what causes overweight. It's a character flaw known as overeating. Calories in, calories out. And the cure is to eat less. The problem is, this treatment has a poor record of efficacy.

Restricting calories is also fraught with problems. Each person's metabolism has a preference for a specific body composition within the context of a particular lifestyle. If total calories are restricted without changing diet composition, the body reacts vigorously to maintain homeostasis. Energy expenditure is reduced; muscle and organ mass diminish. The psychological effects are particularly bad, as anyone can tell you who has been on a low-calorie diet. In 1944, Ancel Keys undertook a calorie restriction trial in conscientious objector "volunteers" in Minnesota. They remained on a 1,570-calorie diet that was low in fat and protein and high in carbohydrate, for 24 weeks. Hardly a draconian calorie count. Here's a quote from the study:

As starvation progressed, fewer and fewer things could stimulate the men to overt action. They described their increasing weakness, loss of ambition, narrowing of interests, depression, irritability, and loss of libido as a pattern characteristic of "growing old".

Some of the men ended up suffering from neurosis and borderline psychosis before the end of the study, one culminating in self-mutilation. This is what we're being prescribed for weight loss?

There are some diet trends that have associated with rising obesity in the US. Per capita calorie consumption has increased. This increase is due to a higher consumption of carbohydrate. Total protein and fat consumption have been almost identical for the past 30 years. This period also saw increases in the consumption of unsaturated vegetable oils, hydrogenated vegetable oils and high-fructose corn syrup. It's hard to say from this association which of these factors (if any) has caused us to gain weight in the last 30 years, but it certainly isn't total fat or protein. Fortunately, we have other clues.

Say Hello to the Kuna

For those of you who haven't been reading the comments, we've been having a spirited discussion about the diet and health of hunter-gatherers here. I brought up the Kuna indians in Panama, who are immune to hypertension, live a good long time, do not gain excess weight, and seem to have less cardiovascular disease and cancer than their city-dwelling cousins.

I was hungry for more information about the Kuna lifestyle, so over the last few days, I've dug up every paper I could find on them. The first paper describing their lack of hypertension was published in 1944 and I don't have access to the full text. In 1997, a series of studies began, headed by Dr. Norman Hollenberg at Harvard. He confirmed the blood pressure findings, and collected data on their diet, lifestyle and kidney function. Here's a summary:

The Kuna are half hunter-gatherers, half agricultural. They cultivate plantains, corn, cocoa, yucca, kidney beans, and several types of fruit. They trade for sugar, salt, some processed cocoa and miscellaneous other foods. They drink 40+ oz of hot cacao/cocoa per day, some locally produced and some imported. A little-known secret: the Kuna eat an average of 3 oz of donut a week. They also fish and hunt regularly.

In the first recent study, published in 1997, the Kuna diet is described as 29% lower in fat than the average US diet (56 g/day), 23% lower in protein (12.2 g), 60% higher in cholesterol, and higher in sodium and fiber. The study doesn't specifically mention this, but the reader is left to infer that 65% of their calories come from carbohydrate. This would be from plantains, corn, yucca, sugar and beans. The fat in their diet comes almost exclusively from coconut, cocoa and fish: mostly saturated and omega-3 fats.

In the next study, the picture is slightly different. Their staple stew, tule masi, is described as being 38% fat by calories (from coconut and fish), exceeding the American average. In the final study in 2006, Hollenberg's group used a more precise method of accounting for diet composition than was used in previous attempts. The paper doesn't report macronutrients as a percentage of calories however.

I was able to find some clues about their diet composition. First of all, they report the meat consumption of the Kuna at approximately 60 oz per week, mostly from fish. That's 8.6 oz per day, identical to the American average.

By putting together the pieces from the later studies, a new picture emerges: a diet high in fish and moderate in protein, moderate in unprocessed fat (especially saturated and omega-3), and moderately high in mostly unprocessed carbohydrate.

Here's my interpretation. The Kuna are healthier than their city-dwelling cousins for a number of reasons. They have a very favorable omega3:6 ratio due to seafood, wild game and relatively saturated vegetable fats. Their carbohydrate foods are mostly unprocessed and mostly from non-grain sources. They also live an outdoor life full of sunshine (vitamin D) and exercise. The chocolate may also contribute to their health, as it contains high levels of potentially protective polyphenols. They're healthier than industrialized people because they live more naturally.

Another lesson to be learned from the Kuna and other exceptionally healthy indigenous peoples is that the human body can tolerate a large amount of carbohydrate under the right conditions. 

Real Food III: Yogurt

Fermented milk is regarded by many cultures as a delicious health food. It has cropped up all over the world in different forms: kefir from Caucasia, laban from the Middle East, dahi from India, creme fraiche from Western Europe, piima from Finland, mursik from Kenya, and yogurt from your grandmother's house. But these same people would scarcely recognize the colored, sweetened gel that passes for yogurt in grocery stores today.

Most if not all dairy-eating cultures ferment their milk. Why is this? There are three main reasons. First of all, unpasteurized milk spontaneously ferments at room temperature, usually becoming delicious "clabbered milk"- whereas pasteurized milk becomes putrid under the same conditions. So fermented milk is difficult to avoid. The second, related reason, is that fermentation prolongs the life of milk in the absence of refrigeration. Fully fermented milk is stable for weeks at room temperature.

The third reason is that these cultures know cultured milk is delicious and nutritious. Fermentation with specially selected cultures of lactic acid-producing bacteria and sometimes yeast work to break milk down into a form that is more easily assimilated. They partly (or fully) digest the lactose, which can be a problem for some people, turning it into tangy lactic acid. They also partially digest casein, a protein in milk that is difficult for some to digest. And finally, the lower pH of fermented milk makes its minerals more bioavailable.

Traditionally, milk was fermented in its unpasteurized state, but raw milk is hard to find in many industrialized countries. Raw milk has its complement of enzymes intact, such as lactase and lipase, which aid in its digestion. It also contains lactose-digesting bacteria that make milk easier for some to digest, and contribute to intestinal health. These are all eliminated by pasteurization. Fortunately, fermentation restores some of the benefits of raw milk. It reintroduces lactic-acid bacteria, along with their digestive enzymes. With that in mind, here's a simple yogurt recipe:


Ingredients/equipment:

1/2 gallon whole, raw or pasteurized, cow or goat milk (add extra cream if you wish)
Starter culture (commercial starter or 2 tbsp of your favorite live-culture yogurt)
Thermometer
Glass jars with lids
Cooler or yogurt maker

Recipe:

1. Heat the milk to 110-115 F (43 C). If the temperature exceeds 115 F, let it cool.

2. Add the starter culture. If the starter is yogurt, whisk it into the milk.

3. Pour the milk into glass jars and keep it at about 110 F for 4-10 hours. 4 hours will yield a mild yogurt, 10 will be tangy. If you don't have a yogurt maker, this is the tricky part. You can use a cooler filled with 100 F water to maintain the temperature and spike it with hot water after a few hours, or you can ferment it in your oven with the pilot light on if the temperature is in the right range.


If you want a thicker yogurt, bring the milk to 180 F (82 C) and let it cool to 110 F before adding the starter. Add fruit, honey or other flavors before fermenting. Enjoy!

As a final note, I'll mention that milk simply does not agree with some people. If you've tried raw milk and homemade yogurt, and they cause intestinal discomfort or allergies, let them go.

Improving Fuel Economy

OK, you know driving isn't good for the environment, but you're going to do it anyway. Here's how to substantially increase your fuel economy without buying a new car:

1- Drive deliberately; accelerate gradually. A car uses a lot of fuel when it's accelerating rapidly.

2- Drive 55 mph on the highway. This makes a huge difference. It maximizes fuel efficiency by reducing wind resistance, which exponentially increases with speed. This reduces gas consumption by more than 20% relative to a speed of 75 mph. 60 mph is almost as good, if 55 is to slow.

3- Draft a truck. Large trucks with flat, square backs leave a massive low-pressure zone behind them, which you can exploit to save gas. At 20 feet behind a standard 18-wheeler, you will use about 27% less fuel. If that's too close, you still save 20% at 50 feet, and 11% at 100 feet. Be careful because trucks have a blind spot behind them, and some truckers do not appreciate drafting.

4- Keep your car well-maintained. Clogged filters, faulty oxygen sensors and flat tires all hurt fuel efficiency.

5- Lose the cargo. The more weight you have in your car, the more fuel is required to get it up a hill or accelerate it.

6- Turn off accessories. AC is the biggest power drain, but the fan used to circulate air also draws power.

Convenience Store Survival Training

I was on the road yesterday driving to a county court to defend myself (unsuccessfully) against a speeding ticket. I reluctantly stopped into a convenience store on my way back, to see if there was anything I would eat for lunch.

I actually did find two things that were palatable and not too unhealthy: canned sardines and toasted cashews. The total was $2.50, affordable even for a grad student.

The sardines were canned in "tomato sauce", which I realized later contained soybean oil. Oops. Well I suppose when you get your food at a convenience store, you have to expect such things.

The main thing that bothered me was the trash. I posted a mugshot (above) of the can, fork and plastic bag that I either trashed or recycled as a result of the meal. The total volume of trash was probably almost as much as the total volume of food.

I think if you stick to nuts, canned fish and fresh fruit, it's possible to survive a convenience store stop. And Baby Ruths. Those are healthy, right?

Two Tons of Steel

While I was waiting for the bus one morning, I decided I'd count cars to see how many were single-occupancy vs. two or more. I came up with a ratio of roughly 20 single-occupancy vehicles for every multiple-occupancy vehicle. The multiple-occupancy vehicles were most often work trucks, containing plumbers or construction workers going to a job.

People have to get to work. Maybe they don't have public transit where they are, or maybe they just don't feel like sitting next to smelly commuters, but for whatever reason, here in the U.S. they drive their cars.

The average American weighs about 180 lbs. Due to our love affair with SUVs, the average American car weighs over 2 tons and climbing. That means every time a person drives a single-occupancy vehicle to work, they aren't just expending the energy it takes to move 180 lbs 15 miles. They're also lugging around a hulking two-ton chunk of steel and plastic. The passenger of the average single-occupancy vehicle is only about 1/24 (4%) of the mass that's being moved to and from work. That's ridiculous!

Of course, we make up for the big weight of our cars with big engines so they can go vroom. That adds up to a lot of gasoline burned, for no clear benefit. In other words, most of us could easily be driving vehicles that perform the exact same function but burn 1/3 the gasoline. I'm not talking about space-age technology here; these vehicles are already on the market.

Why do we commute so inefficiently when better options surround us? I think there are several reasons. First of all, gasoline is dirt cheap. We have no incentive to be efficient beyond our own consciences. Even with the recent price jumps, gasoline doesn't cost much more than it ever has, if you adjust for inflation. In Europe, where high taxes mean gasoline can cost four times as much as in the US, vehicles are lighter and more efficient.

Secondly, we've always been a very car-centric society. Cars appeal to our desire for independence, power and control. A large, powerful car is a status symbol in the US. We've inherited these attitudes from previous generations and we're just beginning to question them. Are there healthier and less wasteful ways of getting to work?

There are, and many of them are very simple. The first and simplest is a carpool. If we put two average Americans in our two-ton car, all of a sudden the people are 1/12 the weight of the vehicle. With four people, the number jumps to 1/6. We've just made our vehicle almost four times as fuel efficient, per passenger! 1,000 lbs per person is still a lot of weight to be lugging around though, so let's look at some other options.

If you are on the market for a new car, fuel-efficient models abound. The new hybrid cars by Toyota and Honda are twice as efficient as their non-hybrid brethren, and not much more expensive. Some people truly need SUVs for their business, but I have good news for them too: there are now hybrid SUVs as well. That's right ladies and gentlemen, they're the most efficient gas guzzlers on the market.

Public transportation is another great option where it's available. Buses are big and heavy but they can accommodate many people.

Now let's get into the really efficient vehicles. Motorcycles and scooters weigh from 250-500 pounds, meaning that a passenger would be from 1/2 to 1/4 the total weight of the vehicle. Now we're beginning to make some sense. Certain scooters can go over 100 miles per gallon of gasoline.

An even better option is to use vehicles that don't burn gasoline at all. A bicycle weighs about 20-30 pounds, making the passenger about 9/10 of the total vehicle weight. That weight ratio might change as the average American loses some weight however. Even if you factor in the extra food you eat when you cycle regularly, it's still terribly efficient. Best of all, bikes allow us to get exercise and feel the sun for a while.

The title for the most fuel-efficient and low-tech vehicle around goes to feet. When using a pair of these, the passenger is 100% of the weight of the vehicle. You can walk until you wear them out and you still won't have burned a single molecule of gasoline. Now that's efficient.

Thanks to lairdscott for the CC photo.

The French Paradox

According to the World Health Organization, 82 out of every 100,000 French men between ages 35 and 74 died as a result of cardiovascular disease (CVD) in the year 2000. In that same year, 216 out of 100,000 men between the same ages in the U.S. succumbed to the same disease.

According to the Food and Agriculture Organization of the UN, during roughly the same time period, the average French person ate slightly more total fat and almost three times more animal fat than the average American. Animal fats came from dairy, lard, red meats, fish and poultry, and contributed to a much higher overall saturated fat intake in the French. This has been called the "French paradox", the paradox being that saturated fat is supposed to cause CVD.

Researchers have been scrambling to identify the factor that is protecting French hearts from the toxic onslaught of saturated fat. What could possibly be preventing the buttery sludge coursing through their arteries from killing them on the spot? One hypothesis is that wine is protective. Although the modern French don't actually drink much more alcohol than Americans on average, wine contains a number of molecules that are potentially protective.

One of these that has gotten a lot of attention is resveratrol, an activator of SIRT1, a deacetylase enzyme that is involved in stress resistance and lifespan regulation. But lo and behold, it turns out that there isn't enough of it in wine to be helpful. Now researchers are turning their attention to a class of molecules called procyanidins, but I suspect that this will turn up negative as well. The protective molecule is probably ethanol, but no one wants to hear that because it doesn't resolve the paradox.

As a person with a French background who has spent quite a bit of time in France, the notion of a French paradox is insulting. It implies that the French are eating an unhealthy diet, but are somehow miraculously protected by a compound they're ingesting by accident. Any French person will tell you there is no paradox. When you make a commitment to seek out the freshest, most delicious ingredients available and cook them yourself, your diet will be healthier than if you count the grams of this and that on your TV dinner.

There's more. Americans consume almost twice the amount of sugar as the average French person. I find this surprising, given the large amount of sugar I've seen on French tables, but I think it speaks to the huge amount of sugar we consume in the US. Much of it probably comes from the high-fructose corn syrup in soda. I'll save my rant about that for another time.

Another thing that stands out about French food habits is the absence of snacking. Mealtimes in France tend to be well-defined, and grazing is looked down upon. I think this is probably essential for maintaining adequate insulin sensitivity in the face of (delicious) refined carbohydrates like baguette.

And finally, the French enjoy their food more than the average nation. I wouldn't underestimate the value of this for health and overall well-being.

So what was the paradox again? I can't remember. Maybe a more parsimonious explanation of the data is that saturated fat isn't so bad after all, and enjoying wholesome food and limiting sugar is the true prescription for health.

Thanks to Gaetan Lee for the creative commons photo.