Ketogenic diets and ketoacidosis

Ketogenic diets and ketoacidosis

Everybody knows that ketogenic diets like Atkins' destroys your kidneys and rots your bones, right? WRONG! Everybody knows that diets like Atkins' cause ketoacidosis which is a very dangerous condition requiring urgent hospital treatment, right? WRONG!

There's a lot of nonsense spoken about ketogenic diets by people who really should know better. I suspect that they have been taught wrongly at uni or med school. As Diana Schwarzbein MD said in the intro' to her first book (see the background to her book).

"In medical training, I was taught that a low-fat diet high in complex carbohydrates prevented weight gain and disease. I believed what my professors said. Early on, I advocated low-fat diets. But this soon changed."

Ketosis is not ketoacidosis

Consider the following four cases:- Note: Figures are from "Introduction to Nutrition and Metabolism" By David A Bender (Senior Lecturer in Biochemistry, UCL)

  1. Healthy human, fed state: Glycogen stores replete. Serum glucose = ~5.5mmol/L. Serum fatty acids = ~0.3mmol/L. Serum ketones = 0mmol/L. No gluconeogenesis occurring. Amino acid pool replete. Cortisol level = normal. No loss of muscle mass.
  2. Healthy human, starvation for 7 days: Glycogen stores depleted. Serum glucose falls to ~3.5mmol/L. Serum fatty acids rise to ~1.2mmol/L. Serum ketones (mainly D-3-hydroxybutyrate) rise to ~4.5mmol/L (not high enough to cause acidosis). Gluconeogenesis occurring. Amino acid pool depleted. Cortisol level = high. Muscle & bone mass slowly decreasing. This is bad ketosis.
  3. Healthy human, low-carb diet: Glycogen stores depleted. Serum glucose falls to ~5mmol/L. Serum fatty acids rise to ~1.2mmol/L. Serum ketones (mainly D-3-hydroxybutyrate) rise to ~4.5mmol/L (not high enough to cause acidosis). Gluconeogenesis occurring. Amino acid pool replete (due to high protein intake). Cortisol level = normal. No loss of muscle or bone mass. This is good ketosis.
  4. Human with untreated type 1 diabetes: Glycogen stores depleted. Due to lack of insulin, the Glu-T4 transporters in cells cannot move to the surface so glucose cannot enter cells. Serum glucose = >20mmol/L. This causes major damage to kidneys, arteries, eyes, nerves etc by cross-linking with proteins (glycosylation) resulting in major disability and eventual death. As the body is forced to run off fatty acids & ketones, metabolic processes are out of control and ketones rise to much higher levels than in 2) or 3) (I don't know how high exactly) resulting in acidosis and eventual death. This is ketoacidosis. I don't know about cortisol levels but they are pretty irrelevant as death by other means occurs.

Conclusion

Low-carb diets are similar to starvation in that serum glucose levels are slightly lower than normal, glycogen stores are depleted and the body is encouraged to burn less glucose & more fatty acids but the metabolic processes are all under control. The big difference between low-carb dieting and starvation is in the amino acid pool and cortisol levels.

Nigel Kinbrum

Evidence-Based Diet, Nutrition & Fitness Information, and Random stuff.



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