How ketogenic (low carb high fat) diets work
A really nice paper was just published by Paoli, Rubini, Volek and Grimaldi in the European Journal of Clinical Nutrition titled “Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets”
You won’t see a better review paper for summarizing the latest in how we think carbohydrate restriction affects various aspects of metabolic health; from weight loss to neurological issues to acne (yes acne!).
A second excellent review article was also published in Nutrition Today by Volek (again!) and Phinney, the low carb gurus. This one is called “A New Look at Carbohydrate-Restricted Diets: Separating Fact From Fiction”. Again this is an excellent scientific review paper.
What I should be doing in this blog is simply drawing your attention to this good work and you can go and check it out for yourself.
Except I’m aware that unless you work at a university, that’s easier said than done. You’d have to buy the papers, which means that most of the people who stand to benefit from the knowledge won’t.
Actually, copyright publishing is a scam of the highest order. What happens is that guys like Volek and Phinney put in heaps of work, often that work is paid for by either public institutions, or by research grants gained through public funds. They then (usually) slave away in the degrading process of blinded peer review, often having to respond to inane comments and endless rebuttals. When they are done, they then sign all of their IP over to a journal, which keeps it all for no cost (and all profit) in perpetuity. Can you imagine anywhere else in the business world that would happen besides academia? It’s laughable, but it is actually what happens to us academics everyday and frankly, we no longer find it funny.
Anyway, I digress. What I really want to do here is summarize the two reviews.
Let’s start with the Nutrition Today paper by Volek and Phinney, which is a nice synthesis of the available evidence for the biology of human energy regulation and homeostasis, and how a carbohydrate restricted diet operates. The main points here are:
- Saturated fat levels in the blood are not associated with dietary saturated fat intake, but dietary carbohydrate intake. They show evidence from both randomized controlled trials and population data for this.
- They discuss in detail what the keto-adapted (fat adapted) state is; how this comes about, including increased beta oxidation of fat, decreased hyperinsulinemia, and a reorchestration of substrate utilization in the body, including the use of ketones to fuel brain function. It is interesting that the majority of practicing dietitians, endocrinologists, cardiologists, and public health physicians have never heard of any of this.
- They point out what is a very important and obvious set of outcomes, which are well documented in the scientific literature; that treating a patient with insulin resistance with a low fat/high carb diet is palliative and going to make the problem worse. If you are having trouble getting glucose into your cells, then reduce the glucose load stupid!
- They show a nice little diagram, which I have reinterpreted and redrawn below, to show the role of dietary carbohydrate in metabolic (dys)function. To quote the authors “The major point is that SFA (saturated fatty acids), and the response to eggs, has a totally different metabolic behavior when consumed in the context of a low carbohydrate diet.”
- They show a meal plan for a typical low carb daily meal. This is excellent as it shows what real and tasty foods we are talking about.
2500 kcal daily food intake restricting carbs
Breakfast (scrambled eggs with sides of spinach and sausage)
- Scrambled eggs: 2 large + 1 tbsp palm oil
- Mozzarella cheese: 1 oz
- Pork sausage: 2 links (48 g)
- Chopped frozen spinach, boiled: 3/4 cup (142.5 g) + 1.5 tbsp butter
- 1/2 Avocado: 67 g
- Swiss cheese: 2 oz (56 g)
Lunch (broiled salmon and a side salad)
- Broiled Atlantic salmon: 4 oz + 1 tbsp butter
- Mixed baby greens: 2.5 cups
- Diced tomatoes: 1/4 cup
- Chopped onion: 1/8 cup
- Feta cheese: 1 oz
- Black and green olives: 4 each
- Blue cheese dressing: 1.5 tbsp
- Peanuts, oil-roasted: 1 oz
- Hood Calorie Countdown milk: 1/2 cup
Dinner (sirloin with sauteed mushrooms and cauliflower ‘‘mashed” potatoes)
- Beef sirloin tips: 3 oz
- Olive oil: 1.5 tbsp
- Sauteed mushrooms: 1/4 cup
- Olive oil cooking spray
- Cauliflower ‘‘mashed potatoes’’: boiled cauliflower 1 cup + shredded cheddar cheese 1 oz + Butter 1 tbsp
- Sugar-free jello: 1/2 cup (121 g)
- Protein: 134 g
- Carbohydrates: 42 g, Fiber 20 g
- Fat: 204 g
- Cholesterol: 853 mg
- SFA: 81 g
- MUFA: 78 g
- PUFA: 28 g
Reproduced from Volek and Phinney (2013), Nutrition Today
Now on to the second paper in the European Journal of Clinical Nutrition titled “Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets”. This is a comprehensive scientific review of the evidence and emerging evidence for the treatment and prevention of a range of chronic diseases with carbohydrate restricted (ketogenic) diets. I have adapted one of their figures into two new ones, showing the state of scientific evidence (strong and emerging separately) for “therapeutic uses of the ketogenic diet”. Hopefully these figures are self-explanatory.
I draw your attention to the “suggested mechanisms” under each one. I’m not going to go into these in detail but it is worth looking at these two figures and noting a few things:
- Carbohydrate restricted diets are a legitimate and well documented approach to the treatment of a wide range of issues.
- There are common mechanisms, mostly about reducing the load of insulin the body has to deal with. This is because the body has to dispose of less dietary carbohydrate. This point is seemingly lost on most in the field of chronic disease prevention and treatment. Hyperinsulinemia is a problem in itself, reducing it helps.
- As well, there are associated mechanisms associated with high insulin. There are problems in the IGF pathway, mitochondrial function, and inflammation.
There is now strong evidence to show that low carbohydrate diets are safe and effective treatments for several conditions, and have some likely positive effects for other conditions.
So that’s it. Two great papers. Hopefully I have captured the essence of what they are saying and where the evidence is at. This is important to get out there into the public and health community. While it’s all behind the paywalls of journals it won’t. So hopefully this helps.