The 5-Minute Carb Story

I recently got into a bit of a disagreement with someone in one of the Foundations courses I’m teaching at Magnus.  We try to add some nutrition discussions into the Foundations curriculum, but we don’t have a lot of time to devote to it.  So, when trying to discuss the topic of carbs this week, this woman in my class with a bio-chemistry background began to push back on some of the points I wanted to make.  Because I literally had 5-minutes to discuss the topic, and because I don’t have enough of a science background to argue with a bio-chemist, I decided to follow up with her via email.  As I constructed the email with the points I wanted to make, as well as a significant about of supporting information, I realized this would make a good blog topic.  What follows can be considered the basics of my recommendations on carbs…

The first point to understand about carbs is simply that there is no such thing as an essential carbohydrate.  Yes our brains run on glucose, but because our bodies can use the gluconeogenesis process to make all the glucose that is needed from protein, we don’t actually need to consume any carbohydrate to stay alive.  As Dr. Emily Deans put it in this article:

"...while there are essential requirements for both fat or protein (meaning we would die without eating at least some fat and at least some protein), we can live quite happily while consuming no carbohydrate at all."

Next we should understand that there's good evidence suggesting that the brain actually functions better using ketones than it does using sugar.  If you aren’t taking in any (or even very little) carbohydrate, your body switches over to ketosis and powers the brain with ketones.  Since the 1920’s Dr.’s have prescribed ketogenic diets for patients with epilepsy.  This article by Shelly Fan from Scientific American states:

“Emerging evidence from animal models and clinical trials suggest keto may be therapeutically used in many other neurological disorders, including head ache, neurodegenerative diseases, sleep disorders, bipolar disorder, autism and brain cancer. With no apparent side effects.”

The bio-chemistry behind this point seems to come down to the idea that the brain has more energy available in a ketogenic environment.  Again the SA article explains this concept well by saying:

"…ketones serve as an alternative energy source to maintain normal brain cell metabolism. In fact, BHB (a major ketone) may be an even more efficient fuel than glucose, providing more energy per unit oxygen used. A ketogenic diet also increases the number of mitochondria, so called “energy factories” in brain cells"

Now that we’ve established the idea that we don’t actually need carbs, are there some good reasons to avoid carbs?  Well yes, there are any number of great reasons to avoid carbs if you’re trying to lose weight, protect your brain, or treat a number of health conditions.  I am not however suggesting that everyone should be eating a very low carb diet, and/or maintaining ketosis.  Simply put, carbohydrate intake should vary based on a person's lifestyle and body fat level.  My general recommendation for people is that if you have significant fat to lose, you should eat a relatively low carb diet.  I suggest people eat under 100g of carbs per day if they are carrying significant bodyfat.  If you are at a healthy weight but do not have a very active lifestyle, you may eat a bit more carbohydrate.  I recommend people in this category stay under 150g of carbohydrate per day.  Lastly, if you do not have fat to lose AND are highly active, I would recommend a little more carbohydrate each day.  How much more would vary from person to person, but carb intake would likely not exceed 250g per day even for the most active folks.  It's also worth noting here that I believe there are populations of people who would thrive on a Ketogenic approach, and there are also people who do fine eating upwards of 200g of carbs per day.  Anyway, this article does a great job of laying out the basics of the approach I suggest.

But wait, if I’m doing cardio don’t I need carbohydrate??  The answer is no!  Your body is always burning some percentage of protein, fat, and carbs for fuel, and the percentages change based on the intensity of the activity.  This article dispels some myths and lays this concept out in laymen’s terms, but here’s the (very) basic idea…  If you’re doing extremely high intensity/very short duration activity (think lifting your max weight on deadlift) you are using ATP as your primary source of fuel which means you’re not really burning a lot of Fat or Carbs.  Once you move into moderate to high intensity/medium duration activities (regular weight training, ½ mile run), you’re accessing your Glycolitic pathway and burning primarily carbs for fuel.  As you transition from that middle ground into low intensity/longer duration activities (walking, jogging, riding long distances) you move into the oxidative pathway which is primarily using fat for fuel.  Here’s a very basic article outlining these topics.  So, in reality that plate of pasta you eat the night before running a 10K, probably does very little to help your performance.

 

The last thing to understand about carbs is that your carb intake should primarily be from cruciferous vegetables.  Obviously, if someone is trying to stay below 100g per day, it's imperative that their carbs mostly come from cruciferous vegetable sources.  As carb intake goes up, we would add in more starchy carbs, and fruits.  Grains should always be avoided for many reasons (a topic for another discussion), and we should always strive to get the bulk of our carbs from veggies. 

As you know I believe in the Paleo template as a fantastic starting place for nutrition, and here is a link to the basics of Paleo.  I think everyone needs to do some experimenting on their own, but Paleo provides a fantastic starting place for optimum nutrition.