DavidPerlmutterMD · 2026-03-17 · David Perlmutter (host), Andrew Koutnik
The Fuel Myth: Rethinking Carbs, Brain Health, and Human Performance | Andrew Koutnik
46 research-tied claims examined: 1 contradicted 2 overstated 7 context 27 supported 3 corroborated online 6 unverified
2 Overstated
Ketogenic dietary interventions have been shown in meta-analyses published in JAMA Psychiatry to therapeutically address mental health disorders including anxiety disorders, schizophrenia, and bipolar disorder.
"We've known for recently its application in various neurological disorders with the emergence of pilot data and now meta-analysis in JAMA Psychiatry showing that these tools can be applied in settings like anxiety disorders, schizophrenia, bipolar." (said at 0:24:15)
A systematic review and meta-analysis on ketogenic diets for mental health outcomes was published in JAMA Psychiatry (PMID 41191382). However, the claim overstates its findings and scope in several key respects: first, the meta-analysis focused on depressive and anxiety symptoms, not schizophrenia or bipolar disorder. Second, while randomized controlled trials (RCTs) demonstrated modest improvements in depressive symptoms, meta-analysis of nine RCTs evaluating anxiety symptoms showed no statistically significant benefit (SMD -0.03; 95% CI -0.18 to 0.12), leading authors to conclude that evidence for anxiety remains inconclusive.
Diamox (acetazolamide) causes mild metabolic acidosis and increases SpO2, but reliably reduces cognitive and physical performance.
"Diamox is a mountain sickness drug that specifically causes mild metabolic acidosis and increases SPO2 levels for people to attenuate mountain sickness when you get to low oxygen levels... when you use something like Diamox, it lasts for multiple hours, but we also know it reliably reduces uh cognitive performance, it reliably reduces physical performance." (said at 0:43:25)
Acetazolamide (Diamox) is a carbonic anhydrase inhibitor used for acute mountain sickness (AMS) prophylaxis. The speaker accurately describes its physiological mechanisms: it induces mild (partially compensated) metabolic acidosis by promoting renal bicarbonate excretion, which stimulates central and peripheral chemoreceptors to increase ventilation and arterial oxygen saturation (SpO2). Evidence also supports that acetazolamide impairs physical/exercise performance at sea level and in several acute hypoxic settings (reducing VO2 max, power output, and time to exhaustion). However, claiming that it 'reliably reduces cognitive performance' is overstated; while acetazolamide frequently causes side effects such as paresthesias, somnolence, and perceived fatigue, robust clinical evidence does not demonstrate a consistent or reliable impairment of objective cognitive function.
- supports: Acetazolamide reduces exercise capacity following a 5-day ascent to 4559 m in a randomised… (BMJ open sport & exercise medicine 2018) · cited 19x in the literature
"Comparing paired individuals at altitude, those on Az had greater reductions in maximum power output (P max ) as a percentage of sea-level values... lower VO 2max... and lower heart rate at P max... Maximum exercise performance at altitude was reduced more in subjects taking Az compared with placebo" (abstract, results)
pubmedfull study (doi) - partial: The Effects of Acetazolamide on Exercise Performance at Sea Level and in Hypoxic Environme… (Wilderness & environmental medicine 2018) · cited 16x in the literature
"This review finds that AZ treated cohorts experience a reduction in time to exhaustion during both submaximal and maximal exercise performance at sea level. At altitude, AZ treated cohorts' recorded widely variable submaximal and maximal exercise performance." (abstract, results, passage verified)
pubmedfull study (doi) - supports: The Impact of Acetazolamide and Methazolamide on Exercise Performance in Normoxia and Hypo… (High altitude medicine & biology 2023) · cited 9x in the literature
"First, we briefly describe the role of CA inhibition in facilitating the increase in ventilation and arterial oxygenation in preventing and treating AMS. Next, we detail how AZ affects exercise performance in normoxia and hypoxia" (abstract, results, passage verified)
pubmedfull study (doi) - supports: Effects of two carbonic anhydrase inhibitors on exercise performance in acute hypoxia. (Journal of applied physiology (Bethesda, Md. : 1985) 2024) · cited 1x in the literature
"AZ and MZ resulted in a partially compensated metabolic acidosis at rest compared with PLA... Overall, both AZ and MZ impair whole body exercise performance in acute normobaric hypoxia." (abstract, results)
pubmedfull study (doi)
Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.