Dear Dr. Wilson,
The body is a pretty finely tuned instrument, sugar is regulated tightly. Why when we are burning ketones during weight loss do they spill over to the urine? I would have thought that they would be produced as and when needed and not be wasted.
Dr Wilson’s Response:
This is an excellent question because the issue of ketosis even confuses many physicians. Ketosis is a normal physiological response to starvation. Our primitive ancestors often went for long periods of time without eating. If you fail to eat for a period of time your body switches from using glucose for energy to using fats. Triglycerides are then broken down into ketone bodies in your liver and these ketones can be used for energy throughout your body including your brain. If the ketone levels in your blood rise high enough some of them will be filtered by your kidney’s and end up in the urine.
When doctors think about ketosis the first thing they think about is diabetic ketoacidosis, a potential deadly complication of type I diabetes. If someone with this form of diabetes doesn’t have enough insulin in their body to allow glucose to be used by cells, their body will start to break down fat to use for energy. Unlike starvation ketosis, this process is pathological, not physiological.
Without adequate treatment patients with diabetic ketoacidosis can die whereas the ketosis associated with starvation is completely benign. The kidney’s tend to clear excessive ketones when you are starving because high levels of ketones can produce acidosis, a potentially unhealthy state. Thus spilling some ketones in the urine is Mother Nature’s escape valve to prevent excessive elevation of ketones leading to acidosis. In patients with diabetic ketoacidosis their body is solely relying on fat for energy so the ketone levels rise to dangerous levels even as some of these ketones are spilled into the urine. I hope my answer his been helpful.
Be well! Dr. Bill Wilson