I'd like to lay out a case for the inclusion of more carbohydrates in a typical Paleo diet. I’ve also been playing with my own diet this year—after quite a few years of eating essentially the same way—so I'll also relate my own experiences.

One common pattern I often see is the guy or gal eating a low carb, strict Paleo diet at, say, around 50 grams of net carbs per day. This person is training hard, hitting regular metcons, and perhaps doing some intermittent fasting on top of it. While this regimen may feel great at first, after a while this person becomes tired but can't sleep well. They find they can't drop some pesky belly fat, often develop a caffeine addiction and are cold all of the time. Finally, they end up with low libido. Yay for healthy living! (I realize not everyone follows a protocol like this one, but I see it often enough that I feel it needs to be addressed.)

First of all, a true Paleo diet—that is, how most humans actually ate over 10,000 years ago—isn't really low carb unless you are comparing it to a standard Western diet. It seems that most modern Paleo authors or authorities advocate a version of the Paleo diet that, from a macronutrient standpoint, more closely resembles how the Intuit Eskimos may have eaten. However, the diet of the Intuit is an exception; not the norm when it comes to contemporary hunter-gatherer diets that have been observed. Published ethnographic research shows that the average range of macronutrient intake for most early humans was likely 22-40% carbohydrate, 19-35% protein, and 28-58% fat. If we take the lowest end of this, 22% carbs, and calculate this over the paltry 1800 calories that our example athlete from above is likely consuming per day, that’s still 100+ grams of carbohydrates a day! If one is consuming a more reasonable 2500 calories per day and we take the high end of that, you'd get 250 grams of carbs daily.

Even the few early humans living in the tundra consumed 6-15% of average daily energy from plant-based foods. Most authors state that early humans ate roots and tubers and mention the above macronutrient ratios, but then go on to recommend a diet that falls outside of this range. I understand their reasoning, as most people today have weight to lose, and low carb diets are very effective. However, if you are a fire-breathing athlete or are already lean, your needs are very different. If you've lost your desired weight eating low carb Paleo, now is the time to adjust your diet.

Let's look at what is going on with our modern Paleo metcon warrior. At first, he feels great eating low carb and fasting. Energy levels stabilize and even increase, thanks to elevated levels of catecholamines (adrenal hormones) and cortisol. The problem begins after these hormones have been elevated for a long period of time. When this happens, he will end up with either fatigued adrenal glands, or down-regulated receptor sites for the adrenal hormones. This may still happen eventually even with good sleep and low lifestyle stressors. Adding in poor sleep and a stressful, too busy life is like throwing fuel on the fire.

Large protein meals without significant carbohydrates still raise insulin levels quite effectively. Cortisol is then released to drive gluconeogenesis in the liver. Adrenaline is also released. If one is performing high intensity exercise regularly, there will be a greater need for gluconeogenesis to refuel the muscles for the next bout of activity. I suspect that this greater demand in an athlete is quite a bit more taxing for the adrenals than in a sedentary person eating low carb.

Many studies have shown a decrease in athletic performance following a low carb diet. However, all of the studies that I am aware of are very short term. There are certainly some longer term adaptations to low carb diets where we can see improved performance. Glycogen sparing and more efficient gluconeogenesis may be some of the longer-term adaptations. It would be nice to see a long-term study done. However, here's the rub: while both short duration alactic activities and long slow duration work can be fueled primarily by fat, glycolytic pathway work can only be fueled by glucose. Lactate can be recycled back to glucose thru the Cori cycle, a process that likely becomes more efficient with regular high intensity conditioning work. However, when the Cori cycle is very active, serum cortisol is higher. Cortisol is also higher in proportion to the demand for gluconeogenesis. This means that an individual performing glycolytic work while on a low carb diet will have higher levels of cortisol and catecholamines than one consuming more carbohydrates. From time to time, this situation would be natural, but when it is a chronic situation is when you will see trouble.

Secretory IgA is an immunoglobulin found mainly in mucus secretions in the body. One of its functions is to inhibit bacterial colonization in the gut. It is also anti-viral. Excessive cortisol or catecholamine levels suppress SIgA. This is not good, as your immune system will be weaker. You'll also have a greater likelihood of poor gut flora, which can lead to a leaky gut and a greater range of food sensitivities over time. It's not uncommon for a Paleo low-carber to develop additional food sensitivities over time, and this might be what's behind it. At least one study has shown that carbs taken during exercise can prevent the drop in SIgA.

Another thing that happens with prolonged ketosis from limited carbohydrates is that one begins to become insulin resistant. Higher free fatty acids during ketosis promote insulin resistance to spare whatever little carbohydrates are available for the central nervous system. Toss in high cortisol from stress due to excessive exercise and quite possibly other lifestyle issues, and you end up with chronically elevated blood sugar—even in spite of a strict low carb diet. If this continues unchecked, then eventually the adrenals cannot regulate your blood sugar effectively anymore. Do you wake up around 3am and have trouble getting back to sleep? Your blood sugar is now dropping too low, and your adrenals are called upon to release cortisol to bring it back up. However, your adrenals are already overtaxed, so insufficient cortisol is released to do the job. Your blood sugar drops even lower, then your body goes to plan B—adrenaline is released to get the job done. At this point, you wake full of energy and can't get back to sleep.

Cortisol and testosterone are manufactured from the same raw materials, so excessive demand for cortisol doesn't leave a lot left for testosterone. As a consequence, T levels go down. I've seen young guys with T levels comparable to a 65-year-old man. There is an interesting study of individuals undergoing the 62-day US Army Ranger training course. The physical energy expenditure is very high and the intake of calories is low. By the second half of the course, the Rangers had T levels that approached the level found in castrated men. While this is an extreme case, I think we can learn from it. Though the rangers’ calorie intake was low relative to their huge energy expenditure, this was not a low carb diet. If it were, the result would likely have been even worse. Though your training and stress may not be that extreme, low carbs or low total calories will produce a similar result.

Carbohydrate restriction also can affect the thyroid hormones. The biology of starvation and carbohydrate restriction are nearly identical. Conversion of T4 to the active T3 is impaired, with the T4 getting converted instead to the metabolically inactive reverse T3. Body temperature and the metabolic rate drops when this happens, and blood glucose begins to run higher. This is correlated also with higher cholesterol levels. A high LDL level is not uncommon in the low carb trainee. Some authorities maintain that a higher protein diet will aggravate hypothyroid symptoms. Furthermore, omega-6 fats have been shown to suppress the thyroid. On a very low-carb diet, a large portion of the total calories will necessarily need to come from fat. As a result, the intake of omega-6 fats from nuts and oils will likely be fairly high, and this may suppress metabolism over time.

But what about ketones? In response to a low carb intake, production and utilization of ketone bodies does increase. The formation of ketone bodies does allow for a lower level of gluconeogenesis. The problem comes when we have excessive stress or exercise demand on the system. Stress actually increases glucose utilization in relation to total energy expenditure. Glycogen stores are depleted faster, leading (once again) to higher levels of cortisol and the catecholamines.

Finally we get to insulin. The popular belief that frequent high carb meals spike insulin too high, leading to insulin resistance, is incorrect. It is a much more complex process than that. Excessive use of processed, nutrient depleted foods, fructose and sugar consumption, omega-6 fats, poor gut bacteria and gluten intolerance are likely more important factors.

What then, should we be eating? First of all, if you are a 180-lb. male and are eating 1800 calories, just eat more! A lot more. Outside of this, I think there are several viable strategies depending on your situation. The first step would be to evaluate the status of your adrenals. This can be done a few ways. You can get a doctor to run an adrenal stress index test. Or, a simple test that I really like is Dr. Bruce Rind's body temperature test. You measure your body temperature at 3, 6, and 9 hours after waking. Average the three values and record. Track this for at least a week. If the values are consistently low, it would indicate less than optimal thyroid function at some level. If the values are irregular, jumping around from day to day, it indicates low adrenal function. Low and irregular values would mean both glands are performing sub-optimally.

If you test low for adrenal function, then I'd suggest eating some carbs with most every meal for now. 20-30 grams per meal might be a good starting point, but you can experiment with more. (I'd also suggest placing the metcons on hold for a while.)

If you have relatively healthy adrenals, then you have a few more options. I really like cyclic carbohydrate intake to get the best of both worlds. Low carbohydrate for 2-3 days, then a big carbohydrate re-feed day. You could also just go with a more random approach to meal composition. High protein and fat sometimes, carbs and moderate protein at others. Just remember that you want to balance things that raise catecholamines (low carb, fasting, underfeeding, stress, sleep loss) with things that lower them (carbs, overfeeding, rest, sleep).

If you are regularly performing metabolic conditioning, even if you limit yourself to 3-5 minutes of very intense activity, then I'd ratchet your carbohydrate intake upward. Consume your carbs not only in the post workout window, but also throughout the day.

If you are already insulin resistant and have high fasting blood glucose, then eating lower carb most of the time will still be your first priority. I'd still suggest a periodic carb re-feed, just less frequently—maybe one carb re-feed meal every 5-6 days.

If you haven't eaten significant carbohydrate for quite a while, you'll likely feel the effects of high blood sugar the first few times you eat carbs. Oral glucose tolerance tests on individuals consuming low carb diets normally show a high blood glucose level after administration of carbohydrates. This makes sense, as the body is somewhat insulin resistant to spare whatever little glucose was being consumed. After a week of eating carbs, though, you normally find that the test will show low blood glucose levels.

One final note on carbohydrates: emphasize starchy tubers and squashes. If one wants to adhere to a Paleo type diet, then yams and sweet potatoes are great options. There are many more varieties of tubers, though. A couple of my favorites are taro and yucca. Peel your tubers, as most of the toxins reside in the skins.

Processed carbs, grains, sugars of all types, and fruit may still cause problems. This article is not a case for their inclusion in the diet. Fructose has proven uniquely damaging to both metabolism and insulin sensitivity. I still only recommend eating fruit in season. Nor am I advocating a truly high carb diet. Stick to 22-40% of calories, just as the ethnographic data suggests.

I'll finish by relating my personal experiences with reintroducing carbs. First of all, I was that guy above. For about 7 years. I stopped doing any regular metcon work over a year ago. My training has since consisted of mostly gymnastic strength work and mobility, along with some O-lifting; almost exclusively alactic pathway work.

I first experimented by reducing my protein and fat a bit, and upping my carbs. Total calories were still the same, a pathetically low average of fewer than 2000 calories per day. (How do I know? Because I track all of this crap daily. Want to know what I had as my second snack on June 21st, 2003? I could tell you.) My first result was better body composition, particularly in the abdominal region. Daily energy was noticeably better, and my sleep improved. General vigor and libido was up. I then did the temperature tracking and found my temperature very low (less than 95 degrees sometimes) and very erratic. After talking to Dr. G. (Garrett Smith), I took a month off from training and ate a minimum of 3000 calories daily for the month. I quickly laid down some body fat, mostly in the abdominal region. At the same time, my triceps, pecs and legs leaned out. This would be consistent with higher testosterone and reduced estrogen. After two weeks, the fat gain stopped, and by the end of the month I was leaning back out - still not training and still “overeating”. My energy is now better than it has been in years, I have no need for coffee (which has always been a problem for me), and let's just say that my wife is very happy. I am consuming between 200 and 250 grams of carbs daily.

Time to get out the potato peeler and get to cookin'! It may be just the tool for increased performance, energy, and vitality.