By Andy Aussem
With no one-size-fits-all solution, how can you know what’s right for your body?
Carbs are evil … but your brain needs them … but they make you fat and sick … but the Food Guide says to eat plenty of them!
I’m sure you’ve heard this argument before. Funnily enough, one of the only things the conventional and holistic health communities can agree on is not having a consistent answer about carbohydrates. Is it low carb, high carb, or something in the middle? To answer these questions, let’s look at the scientific evidence and review the diets of populations free of modern diseases.
Low Carbohydrate vs Ketogenic Diets
Believe it or not, carbohydrates are not on the list of essential human nutrients, and in their absence our bodies create ketones from fat, which enter our energy pathways similar to glucose. In fact, most of our brain can use ketones for energy, which are arguably more efficient than glucose, producing less oxidative stress and inflammation [2, 3]. Our brains do need about 50 grams per day of glucose to function optimally; however, that amount can be supplied through gluconeogenesis, creating glucose from fat and protein.
It’s important to understand that there is a scale of carbohydrate intake, from ketogenic to very high carbohydrate:
Ketogenic = 50 grams or less
Low carbohydrate = 50 to 100 grams
Moderate carbohydrate = 100 to 200 grams
High carbohydrate = 200 to 250 grams
Standard North American diet = 250 grams or more
As you move up the carbohydrate intake scale your body will rely increasingly less on ketones and gluconeogenesis.
Benefits of Low Carbohydrate Diets
There is no shortage of evidence for the benefits of lower carbohydrate diets. Compared to common low fat, high carbohydrate diets, ketogenic diets are effective interventions for weight loss, cardiovascular disease, metabolic syndrome, diabetes, neurodegenerative diseases, traumatic brain injury, epilepsy, polycystic ovarian syndrome, and some cancers [3, 4, 5]. Furthermore, ketogenic diets reduce systemic inflammation, chronic pain, and can improve athletic performance [2, 6, 7].
Similar to ketogenic diets, low-carbohydrate diets are also effective interventions for weight loss, cardiovascular disease, metabolic syndrome, diabetes, subclinical inflammation, and improving athletic performance [7–10].
Additionally, these benefits are seen in the absence of caloric restriction meaning people are more satisfied, can maintain the diet, and have improved quality of life.
Drawbacks of Low Carbohydrate Diets
Two common arguments against low carbohydrate diets are that they are high in fat and protein. Fortunately, a whole food, low carbohydrate diet would not include bad fats (trans and excess Omega 6), and reliable evidence indicates that saturated fat is good for us [13, 14]. A low carbohydrate diet does not need to contain excessive protein and even at the high end of protein intake (30 percent of calories) and in the absence of existing kidney problems, there is no evidence of negative impacts on kidney function . In reality, there is little to no risk associated with low carbohydrate diets; however, the closer the diet becomes to ketogenic, some risk can occur.
Dietary carbohydrate content impacts the metabolism of thyroid hormones because insulin is required in this process . Although there is no clear evidence that ketogenic diets negatively impact thyroid function, many practitioners indicate some patients experience reduced thyroid function with long-term ketogenic diets. Another concern is that ketogenic diets can increase the stress hormone cortisol, leading to a dysregulated hypothalamic-pituitary-adrenal system, otherwise known as adrenal fatigue.
Healthy gut bacteria live off the fibre we cannot digest and there is some evidence to suggest that very low carbohydrate diets can have a negative impact on gut bacteria, reducing number and diversity . These effects may be positive in the short term for pathogenic bacterial overgrowth, but could be detrimental over a longer period of time.
Ketogenic diets can have a positive effect on endurance and short anaerobic (<10 seconds) performance. However, the evidence is mixed for longer anaerobic durations such as interval training, hockey, CrossFit, etc., because these activities rely more on muscle glycogen which is reduced in ketogenic diets [2, 18].
Malnutrition is a viable concern depending on how a ketogenic diet is implemented. If vegetables and fruits are fully removed and the focus is on processed low carbohydrate foods (protein bars) versus whole foods (meat, fish) there will undoubtedly be a level of vitamin and mineral deficiency.
However, aside from some risk associated with long-term ketogenic diets, the evidence is clear that a whole food diet with carbohydrate content between a Standard North American and ketogenic diet is beneficial [19–21].
Quality vs Quantity
Regarding carbohydrate quality, one thing we know is low glycemic load diets are very beneficial for health and further clarity can be gained by reviewing the diets of populations who experience no modern disease . Surprisingly, these groups experience robust health on a wide range of carbohydrate intakes. For instance, the Masai exclusively eat milk and meat while the Tokelu eat a high fat, moderate carbohydrate diet [23, 24]. On the other hand, the Kitava and Okinawa diets are 70 percent to 85 percent carbohydrate, all with the absence of modern disease [25, 26]. However, what differentiates these populations from modern diets is their carbohydrates come exclusively from whole foods, mainly fruits and tubers.
Clearly, both carbohydrate quality and quantity are important factors and there is no one-size-fits-all for carbohydrate intake. Those who are overweight, have metabolic syndrome, diabetes, neurodegeneration, epilepsy, polycystic ovarian disease, or brain injury may consider ketogenic and low carbohydrate diets, while athletes and those who feel better eating more carbohydrates could fall anywhere from low to high carbohydrate intake. Some people even feel better with strategic carbohydrate timing or cyclic ketogenic diets, which may more closely match our ancestral eating patterns. Ultimately, the key is self-experimentation with one connecting factor: it must be a whole food diet with the majority of carbohydrates coming from fruit and starchy tubers.
For references [1–26] supporting this article, please contact the writer.
Andy Aussem holds an Honours Bachelor of Science in Kinesiology and has held a number of professional positions requiring ongoing knowledge of a range of medical conditions. A personal change in lifestyle six years ago led Andy to pursue his Master of Science in holistic nutrition. With one year remaining in his nutrition program, he looks forward to starting his own practice. Andy also operates the wellness blog thebarefootgolfer.com where he combines many of his passions in articles covering everything from ancestral nutrition to exercise to golf.
*Reprint from our Summer 2016 Issue