A while ago I got pointed to a news article with the headline 'Keto diets' could increase diabetes risk, and reading that article hit me with a mix of surprise and disbelief.
The article is about a scientific study where scientists fed one group of mice a “ketogenic diet (KD)” and another group an “obesogenic high-fat diet (HFD)”. What is common about both diets is that they are both very high in fats. However, the “obesogenic” (which means obesity producing) diet is very high in carbohydrates, whereas the ketogenic one is very low in those.
Trying to summarize its findings, the article is quoting one the authors of the study:
Although ketogenic diets are known to be healthy, our findings indicate that there may be an increased risk of insulin resistance with this type of diet that may lead to type 2 diabetes.
This came across as very counter-intuitive to me, as there are diverse anecdotal as well as scientific reports on how various types of low-carb diets can help reversing type 2 diabetes in both mice and humans.
Aside from scientific research, there is a growing number of people who experiment with different types of carbohydrate-restricted diets and publish their results. Amber O'Hearn, for instance, is reporting a lot of success with her experience of living on a plant free diet for many years.
That said, it would be groundbreaking if the finding in that mice study could be confirmed, and shown that this also applies to humans!
The study paper has the title Short-term feeding of a ketogenic diet induces more severe hepatic insulin resistance than an obesogenic high-fat diet (“hepatic” meaning pertaining to the liver), and is providing the following “key points”:
- A ketogenic diet is known to lead to weight loss and is considered metabolically healthy; however there are conflicting reports on its effect on hepatic insulin sensitivity.
- KD fed animals appear metabolically healthy in the fasted state after 3 days of dietary challenge, whereas obesogenic high-fat diet (HFD) fed animals show elevated insulin levels.
- A glucose challenge reveals that both KD and HFD fed animals are glucose intolerant. Glucose intolerance correlates with increased lipid oxidation and lower respiratory exchange ratio (RER); however, all animals respond to glucose injection with an increase in RER.
- Hyperinsulinaemic–euglycaemic clamps with double tracer show that the effect of KD is a result of hepatic insulin resistance and increased glucose output but not impaired glucose clearance or tissue glucose uptake in other tissues.
What's remarkable is that mice on a ketogenic diet develop only some type 2 diabetes symptoms (namely those related to liver function). But what kind of “ketogenic diet” have they been feeding those mice?
According to the “Methods” section in that paper, they've been feeding them
Teklan TD.96355. It is produced by
Envigo, Huntingdon, UK, and contains
15.3% protein, 67.4% fat, 0.6% carbohydrate by mass.
Alright, now there are different types of fats, from which we know that can be more healthy than others (and some of them even essential for a healthy living). So what type of fats does
TD.96355 contain exactly?
Envigo TD.96355 leads to this data sheet providing more details. Most notably, the largest part of that particular “Ketogenic Diet” formula is
Vegetable Shortening, hydrogenated (Crisco) (586.4 g per kg).
What's interesting about hydrogenated vegetable shortening?
Hydrogenation is a chemical process that can convert liquid vegetable oil into vegetable shortening. Unfortunately, this produces unhealthy trans fats as side effect. (It's worth to note that not every trans fat is unhealthy. Conjugated linoleic acids (CLA), which is mostly contained in food products from grass-fed ruminants, might have actual health benefits.)
Among the health problems that are associated with hydrogenated vegetable oil trans fats, there are type 2 diabetes and liver dysfunction. One may wonder whether it is a big surprise that mice are developing exactly those diseases when they are put on a diet that is very high in hydrogenated vegetable oils. Equaling this with a ketogenic diet for humans is undifferentiated and misleading, besides not being sensible at all.
In the end, this is an example of how popular media often cover scientific studies in an undifferentiated way where they blow up research findings. By doing so, they end up spreading half-truths that are often seemingly conflicting with other research. With this irresponsible approach they can do a lot of harm, as it creates confusion, which in turn can drive people to resignation and ignorance.