Dr. Alia Crum on Huberman Lab: How Beliefs Alter Hormones

Crum defines mindsets as core beliefs about a domain (e.g., intelligence, stress, food) that orient our expectations, explanations, and goals. They act as simplifying filters in a complex world, but they are not neutral: believing intelligence is malleable increases effort and persistence, while believing it is fixed reduces motivation. Similarly, beliefs about stress, diet, or illness channel attention, motivation, and physiological responses in specific directions.

In the milkshake study, participants drank the same 300-calorie shake on two occasions but were told it was either a 620-calorie “indulgent” shake or a low-calorie “sensible” shake. When they believed it was indulgent, their ghrelin (the hunger hormone) dropped about threefold more than when they believed it was sensible, meaning their bodies responded as if they had eaten more. Counterintuitively, believing you are eating something rich and satisfying produced a more adaptive satiety response than believing you are eating a diet food.

In the hotel housekeepers study, women who were already highly active at work but did not see their work as exercise were informed—accurately—that their daily tasks met or exceeded Surgeon General exercise guidelines and carried associated health benefits. Four weeks later, without any change in their actual activity, they showed reduced weight and about a 10-point drop in systolic blood pressure compared to controls. Simply changing the mindset about their work—from “just work” to “good exercise”—altered their physiology.

Crum distinguishes between viewing stress as inherently damaging versus as something that can be enhancing. Stress responses can narrow focus, speed processing, and support ‘physiological toughening’ where catabolic stress hormones recruit anabolic hormones that help us grow and adapt. In financial-sector employees during the 2008 crisis, short educational videos emphasizing stress’s enhancing aspects shifted stress mindsets and led to fewer physical symptoms (e.g., backaches, insomnia, racing heart) and better self-reported work performance than both neutral and ‘stress-is-harmful’ messaging.

Just as placebo effects produce real physiological benefits from positive expectations, nocebo effects arise when negative beliefs lead to negative outcomes. People explicitly warned about side effects are more likely to experience them. Crum notes related work on psychogenic fever where believing one is sick raises body temperature by 1–3°F, underscoring that fearful or catastrophic mindsets can induce genuine physiological stress and symptoms even in the absence of new pathology.