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The Carbohydrate Debate – Part 1 by Andrew Aussem

“Carbs make you sick and fat” is a common thing to hear with the recent growing popularity of ketogenic and low carbohydrate diets. But other experts insist that carbohydrates aren’t bad and our brains and body need them to operate optimally.

Funny enough, not having a consistent answer about carbohydrates is one of the only things the conventional and holistic health community can agree on. Is it low carbohydrate, high carbohydrate, 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 an essential human nutrient. In their absence, our bodies create ketones from fat, which enter our energy pathways similar to glucose (1). In fact, most of our brain cells can use ketones for energy and ketones are arguably more metabolically efficient than glucose, producing less oxidative stress and inflammation (23). Then again, our brains do need about 50 grams of glucose per day; however, that amount can be supplied through gluconeogenesis, creating glucose from fat and protein (2).

The above is a description of a ketogenic diet but when discussing dietary carbohydrates 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 – 100 grams.
  • Moderate carbohydrate = 100 – 200 grams
  • High carbohydrate = 200 – 250 grams
  • Standard American Diet = 250 grams or more

Keep in mind that these are loose guidelines and you may see different numbers depending on the source.

Also keep in mind that the carbohydrate numbers listed above refer to net carbohydrates. This means that fibre does not count towards carbohydrate intake. For instance, if one serving of a vegetable contains 10 grams of total carbohydrates and 5 grams of that is fibre, the net carbohydrate amount in that serving is 5 grams.

Benefits of Low Carbohydrate Diets
Compared to common low fat, very 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, 45). Furthermore, ketogenic diets can reduce systemic inflammation, chronic pain, and can improve certain athletic performance (2, 67).

Low carbohydrate diets are also effective interventions for weight loss, cardiovascular disease, metabolic syndrome, diabetes, sub-clinical inflammation, and improving athletic performance (7, 8910).

An important point is that 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 in comparison to low calorie or low-fat diets (11).

Drawbacks of Low Carbohydrate Diets
Two common arguments against low carbohydrate diets are that they are high in fat and protein. However, in the context of whole food, low carbohydrate diets these arguments are not supported by evidence since saturated fat and protein are not bad for us (topic for another day). While there is little to no risk associated with low carbohydrate diets, the closer the diet becomes to ketogenic some risk is possible.

Endocrine Function
Dietary carbohydrate content impacts thyroid hormone metabolism because insulin is required in this process (12). Many practitioners indicate some patients experience reduced thyroid function with long term ketogenic diets; however, there is no scientific evidence of this yet. 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 (13).

Gut Bacteria
Healthy gut bacteria live off the soluble fiber 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 (14). These effects may be positive in the short term for pathogenic bacterial overgrowth but could be detrimental over a longer period of time.

Physical Performance
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. This is because longer anaerobic activity relies more on muscle glycogen which is reduced in the presence of a ketogenic diet (2, 15).

Nutritional Deficiencies
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, etc.) there will undoubtedly be vitamin and mineral deficiency.

In review of the above, we have determined that dietary carbohydrates are not necessarily an essential nutrient and ketogenic and low carbohydrate diets can be very helpful and healthy for many people. However, ketogenic diets specifically have some risk associated with them. So, the question remains how many carbohydrates should we eat? We will answer this question in “The Carbohydrate Debate Part 2” by looking at carbohydrate quality versus quantity, the carbohydrate intake of robustly healthy ancestral populations, and finally, carbohydrate intake suggestions based on biochemical individuality.


Andrew Aussem holds a Master of Science in Holistic Nutrition from Hawthorn University and an Honors Bachelor of Kinesiology. A personal change in his lifestyle 8 years ago led Andrew to pursue further education in holistic nutrition and as a recent graduate he looks forward to starting his own practice at Optimal Being. Andrew also operates the wellness blog thebarefootgolfer.com where he combines many of his passions in articles covering topics such as ancestral nutrition, exercise, wellness, and obviously golf.