Andrew Huberman

Correct: slow, structured breathing (around six breaths per minute) demonstrably increases heart rate variability, at least during and directly after the exercise.

There are small studies showing a reduction in LDL cholesterol, but large and replicated evidence is lacking and quality is variable. It is not a proven cholesterol-lowering agent.

Walnuts are rich in the plant-based omega-3 fatty acid ALA, but the body converts that only to a limited extent into the fatty acids brain cells actually need. Direct evidence for a brain benefit is modest. → How much omega-3 with EPA and DHA do you need per day?

Standard neuroscience: the insula processes signals from the internal organs and plays a central role in how you consciously experience bodily sensations and emotions.

Correct, and it was a surprise: patients without a functioning amygdala still experienced panic when inhaling CO2. Fear triggered from within the body therefore partly bypasses the amygdala.

The mechanism is correct: inhaling CO2 briefly acidifies the blood and triggers feelings of air hunger and panic. How many people actually experience a panic attack depends strongly on the dose and the definition used; 'half' is one outcome from a range of studies.

Correct: classic patient research, including by this speaker himself, shows that damage to both amygdalae strongly impairs the recognition of fear in faces and the experience of fear in response to external threats.

The idea that cold training also makes you more resilient to other stressors (cross-adaptation) is plausible and being researched, but solid evidence in humans is still very limited. → Does cold showering boost your immune system?

Well documented: immersion in cold water substantially increases the release of adrenaline and especially noradrenaline. That is precisely why an ice bath is so invigorating. → Does cold showering or an ice bath speed up your metabolism?

Cold water demonstrably activates the stress system, and that response diminishes with repeated exposure. But whether an ice bath directly dampens the emotional response to psychological stress has barely been studied directly.

Cold raises energy expenditure and activates brown fat; that is real. But the effect is too small to visibly lose fat with. Diet and exercise still do that work; the ice bath is at most a nice bonus. → Does a cold bath or ice bath benefit your health in the long term?