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I certainly function (mentally and physically) better in a state of ketosis. Notwithstanding my personal anecdote, I want to add to your observation on energy/

I certainly function (mentally and physically) better in a state of ketosis. Notwithstanding my personal anecdote, I want to add to your observation on energy/atp (in the mitochondria) efficiency and BHB/ketones. A lot of people counter argue that the body/brain run more efficiently primarily on glucose and glycogen rather than ketones. While it is true if you introduce sugar (glucose) into the blood, cells will generally begin to produce energy/atp primarily from glucose over ketones. However, it is not because the glucose is more efficient, in fact ketones are smaller making them the a more efficient fuel source of the cells. For example, bc they are smaller they cross the blood-brain barrier more easily and are more efficiently used by brain cells to be converted into energy/atp (in the mitochondria). I think there is a reason we call it “getting knocked out of ketosis” because that is our natural state. That is forget high fat/low carb and abstain from all calories and drink only water to stay hydrated and the body will go into ketosis, which is what we are talking about when we discuss “fasting” as a metabolic state (vs say a culturally/religiously defined “fast”).

nradov 8y ago
The body runs more efficiently on glucose when measured in terms of oxygen consumption. That's why very few elite endurance athletes eat ketogenic diets. Their performance is limited by how much oxygen they can metabolize.
- will_brown 8y ago
  I’d say historically (modern history) you didn’t see any athletes eating ketogenic diets, but more and more you are seeing athletes (especially endurance athletes) eating Keto diets. Keto is great for aerobic activity, the idea of a tribe of early man persistence hunting a mammoth for example would have performed better long term in ketosis having unlimited stores of fuel (fat) rather than draining their glucose in 8 or so miles and “hitting a wall”. It’s anerobic activity (sprinting or bodybuilding/Olympic lifting) where there may be a slight detriment in performance. I’ve run marathons in both ketosis and running on glucose. I won’t go there because it’s anecdotal but marathoners, body builders and Olympic style lifters are not the norm and have different requirements especially competing for records. No doubt it’s one thing to live in a natural state of ketosis and treat yourself to a performance boost with some fruit when you are about to burn any glucose than what almost the entire modern world does and spikes their insulin levels all day every day and their body/cells basically not even familiar with how to use ketones as a fuel.
  - nradov 8y ago
    Sure it's possible to eat a ketogenic diet and complete a marathon, but we know from basic biochemistry that it takes more oxygen molecules to produce a given amount of energy from fat metabolism than from sugar. So for elite athletes whose performance is limited by how much oxygen they can get to their muscles it makes the difference between winning and losing.

nradov 8y ago

The body runs more efficiently on glucose when measured in terms of oxygen consumption. That's why very few elite endurance athletes eat ketogenic diets. Their performance is limited by how much oxygen they can metabolize.

will_brown 8y ago
I’d say historically (modern history) you didn’t see any athletes eating ketogenic diets, but more and more you are seeing athletes (especially endurance athletes) eating Keto diets. Keto is great for aerobic activity, the idea of a tribe of early man persistence hunting a mammoth for example would have performed better long term in ketosis having unlimited stores of fuel (fat) rather than draining their glucose in 8 or so miles and “hitting a wall”. It’s anerobic activity (sprinting or bodybuilding/Olympic lifting) where there may be a slight detriment in performance. I’ve run marathons in both ketosis and running on glucose. I won’t go there because it’s anecdotal but marathoners, body builders and Olympic style lifters are not the norm and have different requirements especially competing for records. No doubt it’s one thing to live in a natural state of ketosis and treat yourself to a performance boost with some fruit when you are about to burn any glucose than what almost the entire modern world does and spikes their insulin levels all day every day and their body/cells basically not even familiar with how to use ketones as a fuel.
- nradov 8y ago
  Sure it's possible to eat a ketogenic diet and complete a marathon, but we know from basic biochemistry that it takes more oxygen molecules to produce a given amount of energy from fat metabolism than from sugar. So for elite athletes whose performance is limited by how much oxygen they can get to their muscles it makes the difference between winning and losing.