I still hold to that basic view buts it's been strengthened and given a scientific grounding by an incredible book that I just finished reading called "Good Calories Bad Calories" by Gary Taubes. Taubes is a long time, award-winning science journalist with a special interest in health related science. In an interview in 2008, he describes how he ended up writing the book that ended up taking him five years of research:
"I was doing this story for Science on salt and blood pressure, looking into the controversy about whether salt consumption plays any role at all in raising blood pressure and causing hypertension. One of the prime players in this salt/blood pressure controversy was obviously one of the worst scientists I’d ever met... While I’m on the phone with this guy, interviewing him, he takes credit for getting Americans to eat less fat and fewer eggs. I literally finished the interview, called my editor at Science, and I said 'You know, one of the worst scientists I’ve ever interviewed just took credit for getting Americans to eat less fat and fewer eggs, and I don’t know what the story is, but when I’m done with this salt story, I’m going to look into fat, cholesterol, and saturated fat.'"And five years and 450 pages later, he has written an unbelievably comprehensive look at the science of diet and nutrition as it has been promoted for the past generation. In particular, he explodes the common-sense idea that eating fat causes health problems and, in particular, obesity.
His general argument is that diseases like obesity, diabetes, atherosclerosis, heart disease, stroke, and certain types of cancer, are the result of the rapid and astounding rise in the quantity of refined carbohydrates that we consume. He argument covers a lot of bases - looking at metabolic science over the past 150 years, diet science over the same period, ethnographic studies of diet, etc. He examines studies of numerous pre-modern civilizations that didn't rely heavily on carbohydrates for their energy. The people of Tokelau (an island administered by New Zealand), for instance, had a diet that was composed of 75 percent fat, 50 percent of it saturated fat from coconuts, and yet obesity, diabetes and heart disease were unheard of until the arrival of sugar and flour.
His argument for obesity is basically that we have been looking the wrong way at the usual argument that calories in equals calories out. Dieticians and nutritionists have held that if you eat more calories than you burn, you will put on weight because of the first law of thermodynamics, which is unbreakable. Taubes disagrees with that argument for a very simple reason:
"...if you have an obese mother and a malnourished child living in the same family, and this is a common phenomenon, that should be perceived as a refutation of the calories in/calories out hypothesis."The body, evolved over millions of years, is inclined towards homeostasis. It wants to stay the same. It keeps our temperature the same. It resists losing or putting on weight by adjusting metabolism and hunger - for instance when starved, people become lethargic as the body seeks to conserve energy, when we exercise we hunger for larger, more frequent meals. That's why dieting and exercise rarely work for people who are trying to lose weight - the body adjusts automatically. That's also why, even though there has been an "exercise explosion" levels of obesity continue to rise. Obesity isn't a psychological problem or the problem of a weak will - it is the wisdom of the body trying to ensure it gets enough to provide energy to the cells, organs and tissues. As Taubes notes in the same interview:
"I don’t believe that you can understand obesity and its associated chronic diseases, without thinking of obesity fundamentally as a disorder of excess fat accumulation and asking this question: what regulates fat accumulation? That’s going to be the thing that tells you what the cause of obesity is."And this is where carbohydrates come in. The body can use three sources of energy - carbohydrates, fat and protein. When we eat carbohyrdates, the body breaks them down into simple sugars and then they are transported, via insulin, to our cells. But insulin has another effect, it suppresses the use of fat stores for energy. We eat carbs, our insulin levels spike and all that blood sugar ends up in our adipose tissue as fat. But because our body is storing most of the energy, rather than burning it, our cells remain underfed. So we hunger for more carbs, creating a cycle that over time leads to the accumulation of fat, and ultimately to metabolic disorder in the form of diabetes, etc.
This is a big shift in thinking on obesity, from seeing eating as the cause of obesity to instead seeing it as a symptom of obesity. The body is smart: you're hungry, you eat. Instead of blaming "fat Americans" for being gluttons, which is fundamentally about blaming the victims, we should be looking at why people are eating diets that cause them to get fat. As Taubes notes in an interview with PBS Frontline:
"Basically, up until about 1980, the obesity rates in this country are 12 to 14 percent. And then somewhere in that period between the late '70s and late '80s, they shoot up to 22-25 percent. That's known as the obesity epidemic, and the idea is: What explains it?"Prior to then it was obvious by simply looking at who were the most obese people - it was the poorest, the people most likely to be working hard, manual labour jobs. And the ones likely to be eating the least amount of calories. But they were also the cheapest calories, which are carbs: flour, sugar and starchy grains or potatoes. Accepting this basic premise leads to the next question: why did the consumption of carbohydrates suddenly rise in the late 70s?
When we look at it from this perspective we begin to get a glimmer as to why obesity rates began climbing at this time: the rise in the standard of living that occurred after the Second World War had stopped. Living standards began to reverse, women were forced to work outside the home (not that I'm opposed to women working - just that healthy home-cooked meals were replaced by carb heavy fast foods.), unions were smashed leading to longer hours and harder work and thus more fast food dinners. And this was exacerbated by an ideology that blamed workers themselves for their growing paunches. People sought to reduce their fat intake, companies reduced fat in yoghurt, milk, etc etc. Fat as a proportion of our diets was falling - from 40 to 35 percent - even as carb consumption, especially that of sugar, was rising. We now eat something like 160 lbs of sugar every year, compared to perhaps 40 lbs at the turn of the twentieth century. The gluttony theory of obesity also serves to hide the fact that our lives are getting worse. "Look at you," we're told. "You've never had it so good. You're so well off that you're fat." But it is a lie, our sweet tooth is masking with obesity the fact that we're hungrier than ever.
Taubes himself doesn't explore the social and political drives behind the obesity epidemic. For that you'll have to look elsewhere. But his examination of the "diseases of civilization" and explosion of the myth of fat as the cause of it is well worth the read. It is a long book and can get quite detailed, particularly some of his discussion of fat metabolism, but you won't regret it. And, good news, it's available in the Toronto Public Library.