Why low-carb isn’t crazy

21 January, 2009

I had a short argument with my boss the other day about my current diet, which cuts out pretty much all carbs except an apple or two a day. She insisted that this is unhealthy – she said that “The brain needs sugar.”

I tried arguing that losing weight ultimately means reducing energy intake, or increasing energy usage. When she goes walking to lose weight, where does she think the energy to walk comes from? The body uses what joules are in the blood (coming in via digestion of carbs and sugars), but this doesn’t cause weight loss, having a preventive effect at most. The weight loss comes when this energy has been depleted – now the body begins using its fat stores.

Why is a low carb diet still so shocking? People are used to taking in a large amount of carbohydrate, sugar and fat every day, and they get cravings if they attempt to cut down or desist. Thus they assume that this high energy diet is crucial to normal health.

However, our hunter-gather ancestors did not have bread and pasta and rice in their diets, yet somehow managed to live to adulthood, reproduce, and spread their species all over the earth. Most other animals do not share our modern high-energy diet; our primate relatives largely subsist on leaves.

Here’s an interesting thing: about 10,000 years ago, people started living in permanent settlements and farming their food. In particular, they farmed wheat and other grains for bread. What attracted humans to grain foods? If you’ve ever seen a head of wheat, you’ll know that getting the grains out is difficult. Once you have a few grains, you’ll find they are very hard and almost impossible to chew. And these are the domesticated breeds we’ve developed over 10,000 years – the original wild grains would have been even more recalcitrant.

You have to have a very large field of grain to feed a tribe their daily bread. You have to reap the grain, thresh out the grain, and do this a lot if you want more than a couple of biscuits’ worth. You have to grind the grains with stones, then combine the powder with water to make handling it easier. Some bright spark discovered that cooking this mixture made it taste better, and also reduced the indigestion caused by eating something that is essentially glue.

Why was this so attractive to our ancestors, when our hunter-gatherer diet had consisted largely of foods that did not require such time and effort to make edible? What drove them to abandon their old way of life, and their old diet?

The cause is biological. In the wild, certain nutrients that are essential for our survival are very rare. Of our ancestors, those who craved the taste of foods containing these nutrients out-survived those who did not, and so these cravings became universal characteristics. We can deduce what these food properties are simply by examining our own cravings: we like salt, we like sugar, we like fat, we like protein, we like carbohydrates (which our body converts to sugar).

Now, silly old evolution didn’t know that we would crave these things so much that we would actually settle in farming communities in order to produce more of these foodstuffs, nor that our intelligence would eventually enable us to produce an overabundance of these foods. Evolution never imagined that our cravings would drive us, and our culture, to our current situation, where we can freely eat so much of this stuff that it’s not good for us, it’s bad for us.

Now those of us who are healthiest are those who do not crave the essential nutrients, and those of us who are conscious of what we eat. You don’t need to be pro-ana to see that our ultra high-energy diets are abnormal and unhealthy, but you do need to realise that when dieticians say “eat more green leafy vegetables and fruits”, what they don’t go on to say, but should, is “cut down drastically on high energy foods like grains and potatoes”.

Grains and potatoes, by the way, are touted by the WHO and other do-gooders as the solution to the world’s food problems. Yeah, they are cheap and easy to grow, but why not just recommend eating at McDonald’s instead? You’ll be at least as healthy as if you subsisted on bread and potatoes – just ask the Irish. This simplistic dietary solution to world hunger exacerbates our blindness to the abnormality and unhealthiness of the modern, civilised diet.

The healthiest way to eat is lots of vegetables, and a little bit of meat. I’m not even sure we should still be eating dairy – after all, what wandering tribesman gets to regularly milk a large quadruped for his pleasure? (Oo-er, that sounds rude!) Sure you need calcium, but you are probably losing a lot of calcium due to eating too much salt and protein (including milk protein); (also alcohol, caffeine and tobacco, and foods containing phosphorus). You can get a good amount of calcium from green leafy vegetables (but not spinach and chard), eggs, nuts and fish (broccoli and oranges are both a great source of calcium). Exercise also helps stop the bones losing calcium.

So go ahead and cut out carbs – it’s a healthy thing to do. You will suffer cravings, but it’s probably not as bad as coming off heroin, right?

(But if you start fainting, or your skin turns a funny colour, you should probably examine your diet a bit more closely. And after you turn 40, you should probably have your calcium levels occasionally checked, just in case.)

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