The traditional Inuit (Eskimo) diet is very high in fat and protein from sea mammals, fish, and land animals. It is also very low in carbohydrates due to the scarcity of fruits, vegetables, and grains in the Arctic region. This special diet means that many Eskimos are believed to be in a state of nutritional ketosis, where their bodies burn fat rather than carbohydrates for energy. But is this always the case? Let’s take a closer look at the evidence.
What is ketosis?
Ketosis is a metabolic state where the body uses ketones derived from fat as its main fuel source instead of glucose from carbohydrates. Blood ketone levels typically over 0.5 mmol/L indicate nutritional ketosis.
When carbohydrate intake is very low, below 50 grams per day, the body shifts to burning fat through beta-oxidation. The liver converts fatty acids into ketone bodies – acetone, acetoacetate, and beta-hydroxybutyrate. The brain can use ketones for over 70% of its energy needs when glucose is limited.
Being in ketosis allows the body to go for longer periods without food and enhances fat loss. It takes strict restriction of carbohydrates to reach and sustain ketosis.
The traditional Inuit diet
The traditional Inuit diet consisted of:
– Seal, whale, caribou, Arctic char and other fatty fish – Provided protein and fat, including omega-3s.
– Walrus, seal, whale blubber and skin – Rich sources of fat.
– Shellfish, seaweed, bone marrow – Sources of vitamins and minerals.
– Berries and lichens – Very low in carbohydrates.
Estimates suggest the traditional Inuit diet provided approximately:
– 50–75% of calories from fat
– 20–30% of calories from protein
– 5–15% of calories from carbohydrates
This macronutrient ratio would classify the Inuit diet as ketogenic. Compared to the typical modern diet, it had far more fat and protein and minimal carbs.
Evidence the Inuit diet caused ketosis
Several lines of evidence suggest the traditional Inuit diet led to ketosis:
– Low carbohydrate intake – Below 50 grams of carbs per day induces ketosis in most people.
– High fat intake – Fat provides the alternative fuel source in the absence of adequate glucose from carbs.
– Protein intake insufficient to prevent ketosis – Protein can be converted to glucose but the Inuit diet was not high enough in protein to provide sufficient glucose.
– Anecdotal reports – Early Arctic explorers described the urine of the Inuit as smelling sweet like acetone, suggesting the presence of ketone bodies.
– Isotope studies – Analysis of hair from 500-year-old frozen Inuit mummies shows a metabolism based on protein and fat rather than carbohydrates.
– Gene studies – The Inuit have genetic adaptations to high fat, low carb diets. Variations allow for the more efficient metabolism of fatty acids for energy.
– No access to carbs – The Arctic environment provides almost no access to dietary carbohydrates year-round.
This evidence indicates Inuit were very likely in sustained nutritional ketosis for much of the year.
How deep was Inuit ketosis?
Studies measuring blood ketone levels among the Inuit eating traditional diets are limited but suggest they achieved mild-moderate ketosis:
– A 1970s study found average blood BOHB levels of 0.7 mmol/L in Inuit after a regular meal during winter. This is considered mild ketosis.
– A study in 2008 measured blood ketones of 0.4 mmol/L in Greenland Inuits eating traditional diets. Also mild ketosis.
– For comparison, nutritional ketosis is commonly defined as blood ketones of 0.5-3 mmol/L.
– Levels above 3 mmol/L indicate possible dangerous ketoacidosis.
This data indicates the Inuit diet induced light to moderate ketosis rather than dangerous heavy ketosis. This level of ketosis could provide much of the known benefits of being in ketosis while avoiding risks from very high ketone levels.
Did ketosis persist year-round?
The Inuit diet and metabolism likely shifted seasonally:
– Winter – Deep ketosis. High fat intake from seals, whales. Minimal carbs.
– Spring – Moderate ketosis. Increasing protein from sea mammals, fish. Some carbs from berries.
– Summer/Fall – Low ketosis. More carbs from gathered plant foods. Less reliance on fat.
So ketosis was likely deepest in the winter months when sea mammals made up a larger portion of the diet. In the spring and especially summer, increased carbohydrates may have pushed the Inuit out of ketosis periodically.
But the seasonal availability of carbs was still low enough that they still spent more time in ketosis during the year than out.
Does the modern Inuit diet cause ketosis?
The modern Inuit living in Arctic regions now have much more access to imported carbohydrate-rich foods than their traditional diet allowed.
Studies looking at the ketogenic nature of the modern Inuit diet find:
– Average per-person carbohydrate intake increased from 54 g/day in 1956 to 289 g/day by 2007.
– Remaining high fat intake comes more from processed oils than blubber and skin.
– Protein intake has also increased significantly.
This breakdown suggests that the substantial increase in carbohydrates and protein from modern foods pushes the modern Inuit diet safely out of the ketosis zone much of the year.
Unless an individual Inuit purposefully restricts carbohydrate intake again to below 50 grams per day, the modern diet does not produce ketosis to the extent the traditional diet did.
Health impact of the dietary change
The nutrition transition from the traditional to modern Inuit diet has unfortunately led to a rise in chronic health conditions:
– Overweight and obesity rates were very low on the traditional Inuit diet but now are similar to the general North American population.
– Diabetes was extremely rare before but has increased dramatically amongst Inuit in the last 50 years.
– Heart disease and stroke were uncommon on traditional diets but are now major causes of death.
– Dental cavities have also become much more common now that sugars and starches make up a larger percentage of total calories.
This rise of chronic diseases correlating with the dietary shift away from ketosis provides indirect support for the health benefits of long-term ketosis.
Can anyone safely eat an Inuit style ketogenic diet?
It is possible for nearly anyone to safely enter nutritional ketosis by restricting carbohydrates sufficiently. However, some considerations apply to attempting a long-term traditional Inuit style high-fat ketogenic diet:
– Get essential nutrients – Ensure sufficient intake of vitamins C, D, E, potassium and other hard-to-obtain nutrients on a ketogenic diet. Use supplements if needed.
– Avoid ketoacidosis – Do not overly restrict protein alongside carbs to prevent high ketone levels. Moderate protein intake provides glucose without disrupting ketosis.
– Increase meal frequency – Eat 4-6 small ketogenic meals throughout the day. Do not go more than 5-6 hours without food.
– Avoid overeating on fat – Ketosis suppresses appetite, so fat intake does not need to be extremely high. Stick to minimum needed to maintain ketosis.
– Prefer unsaturated fats – Prioritize omega-3 rich fats from oily fish and avoid excessive omega-6 intake.
– Stay hydrated – Drink sufficient water and electrolytes like sodium and magnesium.
With some prudent modifications, it may be possible to recreate much of the fat burning effects of the Inuit ketogenic diet today. Consult a knowledgeable practitioner before attempting very low carb ketogenic diets long-term.
Conclusion
Evidence suggests the traditional Inuit diet was able to produce mild-moderate, but not dangerous, ketosis for much of the year. This was due to the very high fat and protein intake alongside minimal carbohydrate availability. However, the nutrition transition over the last century has added more carbs to the modern Inuit diet, likely pushing them out of ketosis for larger portions of the year. Some revival of lower carb, high fat, moderate protein Inuit-style eating may provide health benefits today with careful implementation. But the Inuit cannot be assumed to be permanently in ketosis on modern diets.