The matter is thus: we’re eating all wrong in this country, and it’s not in the ways you might think.
At some point within the last half-century or so, a travesty of bad science became enshrined as the right, healthy way to eat. The reasoning went something like this…
Some populations we’ve studied have high levels of both serum cholesterol and heart disease.
Some foods contain larger amounts of cholesterol than others.
Therefore, to prevent heart disease, people should eat foods with less cholesterol in them.
…Can you spot the myriad errors of reasoning there? The principal ones are first, that some populations have high cholesterol and low incidence of heart disease, and some have low cholesterol and a great deal of heart disease; and second, that eating food with cholesterol in it does not necessarily raise one’s serum cholesterol levels. The assumptions are all wrong. But this mistaken picture led to the idea that fatty, high-cholesterol foods will “clog your arteries”, a concept now so ubiquitous as to go unquestioned.
Whenever true, experimental science is conducted on this question (and related questions about the genesis of obesity, Type II diabetes, and the like), the picture we discover is very different. In fact, these foods so universally demonized can have a protective effect against heart disease and other ills, while the kinds of foods that have been promoted to replace them–starches and sugars, the carbohydrates–cause terrible damage to the body.
How does that happen? The answer lies with insulin, one of the hormones involved in metabolism, the way your tissues use energy. Insulin is used to to keep your blood-sugar levels from rising too high. So when you consume a meal rich in sugars or starches (which rapidly break down into sugars during digestion), the pancreas secretes insulin. However, there’s an unfortunate side effect: insulin is also the hormone that signals the body to conserve energy as fat. So those sugars get stored away in fat tissue, and the energy the body was expecting to get out of your meal is locked away, inaccessible. This in turn causes weight gain, fatigue, and a persistent sense of hunger.
It gets worse. The process of carbohydrate metabolism also promotes the formation of a damaging pattern of cholesterol-bearing proteins called small LDL. These are the “bad cholesterol” implicated in heart disease: they can leak through inflamed artery walls and form the artery-hardening plaques we know so well.
And it gets still worse from there. Chronically high levels of insulin cause a condition known as insulin resistance, where the body needs more and more insulin to achieve the same effect it used to, like growing a tolerance to a drug. So the pancreas must work harder whenever you eat one of those carb-heavy meals, and the ensuing weight gain, sluggishness, and so forth get worse.
The answer, then–the way to prevent or undo these metabolic disasters–is to quit eating those carbs! Without a spike in insulin, the body puts much more of the meal to work as usable energy. You feel more satisfied, more lively, and don’t gain weight (in fact, you’ll likely lose some!). If you’ve suffered a lot of metabolic damage from high insulin, it can take some time to reverse the trend, but study after study shows that this is the one reliable way to do so. It requires real dedication to slashing carb intake; this is not a diet you can go on for a few weeks or months and then give up. But it works!
After learning these things, first from a talk by some physicians at my workplace, then by reading the book Good Calories, Bad Calories by Gary Taubes, I knew I couldn’t keep eating the way I had to date. If a relatively simple change of lifestyle like that could keep me from gaining middle-age pounds and improve my heart-disease risk factors, why not? Lo and behold, fifteen pounds came off within a couple of months.
I’m still learning about all this, though, and there are some questions I haven’t found conclusive answers to. I’ve jotted them down below.
– I’m a pretty lean build already. There’s some evidence that a little bit of overweight can be protective. How much weight reduction is too much?
– How important are fruits and vegetables to a low-carb diet? Is fiber valuable, or a waste of space?
– If a starch is “whole grain,” is that acceptable in moderation? (Actually, I’m pretty sure the answer’s “no” on this one. A whole-grain carb is sort of like a filtered cigarette: it’s still terrible for you, just a little less terrible.)
– Is there anything wrong with eating a lot of dairy (cheeses, etc.)? Hardcore “Paleolithic diet” advocates seem to say yes, but most other low-carbers don’t mind it.
– Nutritionists on both sides of the low-carb vs. low-fat debate tend to agree that highly-processed, artificial foods are bad news. Much is made of the “pink slime” in grocery-store meats and so forth. Is it worse to eat low-carb but processed food, or more natural but higher-carb food?