Anonymous asked: From my understanding, glucose (which comes from the breakdown of carbohydrates) is the body's #1 source of fuel & the best source of energy for the brain. Ketosis & eventual ketoacidosis that occurs from lack of carbs is not beneficial in the longterm & is potentially harmful. My RD said that carbs are necessary for longterm health. I would love to hear your opinion on this since you are a doctor (& I am not) therefore your opinion is professional, if you don't mind explaining why you eat keto.
Hi there! You’re right - glucose is the endpoint of ALL carbohydrates.
Your RD is confusing nutritional ketosis with ketoacidosis, which occurs in type 1 diabetics.
When type 1 diabetics don’t use insulin, they are effectively in a state of starvation. Type 1 diabetes refers to an autoimmune condition in which the insulin-producing cells of the pancreas are destroyed.
In normal people: insulin is a hormone which regulates blood sugar (among other things). When you eat carbohydrates, which are broken down to glucose, they enter your bloodstream and raise your blood sugar above the ~homeostatic range~. Insulin is released in response to this (bodies love things to lie within the ~normal range~), and glucose is taken up by the muscles, and used to replenish glycogen. Any glucose in the blood beyond what is necessary to be used ~right now~ by the body, is stored as fat - insulin also stimulates fat cells to take up triglycerides.
You can take from this: carbohydrates drive insulin which drive fat storage.
In a diabetic, they have no insulin, therefore the glucose in their bloodstream is redundant, and increases in concentration as there is no hormonal response to it, therefore it cannot be used. They are effectively in a state of starvation. Carbohydrates are not necessarily the ~best source~ of fuel for the brain, but they are the usual. Only glucose and ketones can cross the blood brain barrier for fuel (other tissues can use fat directly), and so because glucose can’t be used due to no insulin, ketones are produced. However, there is no feedback loop in place to regulate the production of ketones, so they increase to the point in which blood pH levels are deranged —> ketoacidosis. This IS a dangerous state.
Nutritional ketosis, on the other hand, involves dropping carbohydrate intake (and also protein, as too high a protein intake can also produce an insulin response) to the point where glycogen is no longer the body’s preferred fuel between meals, but fat. As I said before - our brains can’t burn fat directly - therefore ketones must be produced to cross the blood brain barrier and provide our minds with energy. Our brains are very consumptive organs, and they burn a significant proportion of our calorie intake on a day to day basis.
In both nutritional ketosis and ketoacidosis, the brain is using beta-hydroxybutyrate, however levels in nutritional ketosis generally lie between 0.5 and 3.0 mMol/l instead of 15-20mMol/l. This isn’t enough to alter blood pH, or cause problems with blood sugar levels (and in turn, blood osmolality). Any sugars consumed (however little they may be), will induce a slight insulin response in a normal individual, that will keep blood sugars within the normal range.
Ketosis is a physiological state for survival. There’s no way cavemen ate six small meals a day - they probably often didn’t even know where their next meal was coming from! Being in ketosis means you feel hunger ~differently~ because of this - not only do you use dietary fat as a source of fuel, but your body unlocks its own fat stores to be used at the ready should you skip a meal or two.
Great response and explanation.