Much like the Trojans and Spartans fought a bloody war for ten long years over the kidnapping of Helen, two armies are now doing battle over dietary recommendations. On one side, we have the low-fat army, on the other, the low-carb warriors.
In my last post, I showed you why the low-fat philosophy is a sham: it is based on bad science and unquestioningly accepted due to government support, pervasive advice, and public misunderstanding.
Today, I take on the other side.
The Carbohydrate Hypothesis
According to conventional wisdom, it is our high-fat diets that are to blame for the obesity epidemic, as well as the ever-increasing rates of cancer, diabetes, and heart disease. The “carbohydrate hypothesis” is an alternate view that basically flips this all on its head and puts the blame squarely on the shoulders of carbs.
The basic map goes something like this: carbohydrates —> insulin secretion —> fat accumulation —> metabolic syndrome —> diseases of civilization (DOCs).
You see, your body breaks down the carbohydrates you eat into shorter glucose molecules. The hormone insulin is then released in order to properly metabolize these sugars. However, insulin plays another role: it stores fat molecules away and prevents their release into the bloodstream.
Sounds like a perfect storm of beer belly creation, eh? If you simply cut carbohydrates out of your diet, your body literally cannot store fat, and even better, you become ketogenic and your body preferentially burns fat as fuel rather than carbohydrate or muscle protein. Sounds like a good deal, huh?
Except for one problem: it doesn’t work that neatly in real life.
The Problem with Low Carb
If excessive carbohydrate intake truly disposes one to greater risk of obesity, then we should expect to find a strong correlation between carbohydrate consumption and fat accumulation across all time and cultures, right?
Here’s where the whole carbohydrate hypothesis breaks down.
Literally billions of people across Eastern, Southeastern, and Southern Asia consume massive amounts of carbohydrates, most obviously in the form of rice. And yet they seem to be no worse for the wear, health-wise. Their rates of obesity are incredibly lower than in first-world countries. And the people of Okinawa are rightly revered for their consistently long lives, despite (or because of?) their high-carb diets.
Likewise, the Kitavans of Papua New Guinea eat a staggering 69% of their calories from carbohydrates. Yet they are healthy, strong, and practically free of diabetes, heart disease, and cancer!
An Underdog Story
I must admit that I have a soft spot for the low-carb community.
It reminds me of the 1980 “Miracle on Ice,” when the incredibly skilled and dominant U.S.S.R. hockey team (let’s call them the “low-fatters”) were toppled by the scrappy United States underdogs (let’s call them the low-carbers). Maybe I’m just a bit of an anarchist, but I really love rooting for the little guy.
The way I see it, the low fat paradigm doesn’t have to do anything more at this point to convince anyone that it is “right.” Most people born in the eighties or later were raised from day one believing that saturated animal fat and cholesterol consumption will not only end up killing you at age 45 from a heart attack, but you’ll also require a special-made coffin to fit your 350 lb bulk in.
It seems that most of the people who believe dietary fat is unhealthy can’t give an articulate answer of why they think this way. “But everyone knows fat is bad for you!” Yikes.
Any “alternative hypothesis” has a ton of ‘splainin’ to do if they are to convince anyone, and people in the low-carb community have certainly put forth a lot of controversial and intelligent ideas challenging the status quo.
But in the end, the “carbohydrate hypothesis” is as flawed as the “lipid hypothesis,” and makes most of the same errors of bad science.
Good Carbs, Bad Carbs
I am a big fan of the interest in the evolutionary human diet that seems to be blowing up so much recently, but I have many reservations about how most people interpret it. First and foremost is the widespread damnation of carbohydrates among the Paleo crowd.
Our ancestors ate plenty of starchy roots, tubers, and bulbs during our evolution. Which means they hardly ate low-carb.
Although insulin is rightly pointed out as being a “fat storage hormone,” it plays more roles than just that. Insulin also acts as an appetite suppressant. And fat storage is still possible even without insulin present.
In reality, the insulin spikes from carbohydrate consumption are likely of no concern to you. As long as your body is responding to this hormone effectively, you should be fine. As insulin levels go down after eating, the fat that was briefly locked away in your cells is now free to be released and burned. The only times you need to be worried about carbohydrates are if you are a diabetic or if you are insulin resistant (generally found in obese, inactive people).
Your body needs the carbohydrate glucose, but it does not need fructose. And although your body can produce glucose on its own, I’d suggest adding some into your diet in the form of starchy roots, tubers, and bulbs such as potatoes, carrots, and onions, particularly if you are physically active.
I would also suggest limiting the amount of fructose you consume. Eating too much (which is what most people are doing) is the likeliest cause of the metabolic syndrome that causes so many people to pack on extra fat, along with all the DOCs that come along with it.
To do this, I suggest you drastically restrict the amount of sugar you consume. Unfortunately, it is in absolutely everything, and in very large doses. (We Americans have a strong sweet tooth.) If you cut out sodas and start preparing most of your meals yourself, you will have won 99% of the war. Many people take it a step further and criticize fruits for their fructose content, but I’d say keep ‘em if you really want ‘em. Fructose is dose-dependent and a little isn’t going to hurt you, especially when you eat them in fiber-rich fruit as opposed to caffeinated sugar water.
The Bottom Line
In an increasingly polarized dietary world, you don’t need to be either low-fat or low-carb. Most evidence suggests that humans evolved eating plenty of starches, and many traditional societies to this day eat plenty of carbohydrates and yet have fantastic health and fitness.
The “carb-insulin-fat” hypothesis is interesting, and calls out the low-fat hypothesis on all of its inconsistencies and crap science, but it ultimately doesn’t hold up under scrutiny. The very few of us who are carb-sensitive should be careful, but for the rest of us, simply cutting out most of the sugar and flour will do wonders to improve your body composition and overall health.
So stop skimping on the potatoes, forcryinoutloud!