Pooling 60 randomized trials and 4,554 people, open-label placebos had a small overall effect of 0.35 standard deviations. It was larger in clinical groups than in healthy volunteers, and much larger for self-reported outcomes (0.39) than objective ones (0.09).
the research library the whole person
mindset and the body
What you believe about a meal can change how your body answers it.
Expectation moves things you can measure, and it is also the most oversold idea in wellness. This page puts the strongest findings next to the failed ones so you can see exactly where the line sits.
12papers
12studies in people
3counterpoints
this page, by tier
- 6 human evidence
- 6 early human
- 0 lab + animal
- 0 background
the short version
what the research found
the headline numbers
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84 hotel housekeepers told that their work already counted as exercise showed lower weight, blood pressure and body fat four weeks later, with no measured change in what they did.
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The same 380-calorie milkshake, labeled a 620-calorie indulgence, dropped the hunger hormone ghrelin far more steeply than when it was labeled a 140-calorie diet shake.
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Across 60 trials and 4,554 people, open-label placebos helped self-reported outcomes (0.39 standard deviations) but barely moved objective ones (0.09).
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Adults who had a lot of stress and believed it hurt their health a lot had a 43% higher rate of early death over the next eight years.
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Across 63 studies and 97,672 students, growth mindset programs averaged an effect of d = 0.05, which disappeared after correcting for publication bias.
my honest bottom line
Open-label placebos, where people are told plainly that the pill is inert, show a small but real effect on symptoms people report. The same research found almost nothing on objective measures, so I read belief as strong for how you feel and weak for what shows up on a lab report.
evidence at a glance
12 papers
- human evidence6
- early human6
- lab + animalnone yet0
- backgroundnone yet0
Includes 3 counterpoints.
every title links to the original
the papers
Sorted from the strongest human evidence down to the lab work and background reading. Counterpoints are marked, and they stay in on purpose.
Across 63 studies and 97,672 students, growth mindset programs averaged d = 0.05, non-significant after correcting for publication bias, and 0.02 in the six best studies. Authors with a financial stake in the programs reported larger effects.
A preregistered national experiment in US high schools: one online session under an hour raised grades among lower-achieving students and increased enrollment in advanced math, but only in schools where peers supported the message. It holds up because it was preregistered and independently reanalyzed.
Two meta-analyses covering 273 studies and 365,915 people found the link between growth mindset and grades, and the effect of mindset programs, weak overall. The exceptions were students from low-income families or who were academically at risk.
In 28,753 US adults linked to death records, those who reported a lot of stress and believed it hurt their health a lot had a 43% higher rate of early death. It is observational, so the belief and the underlying health may not be separable.
Comparing placebo with no treatment across 130 trials, placebo had no significant effect on yes-or-no outcomes. Continuous outcomes showed a small benefit that shrank as trials got bigger, a sign of small-study bias, worth about 6.5 mm on a 100 mm pain scale.
show all 12 papersshow fewer
97 adults with low back pain for more than three months added openly labeled placebo pills to usual care. Pain fell 1.5 points on a 10-point scale versus 0.2 with usual care alone, and when the usual-care group later switched to open placebo, their pain fell by a similar amount.
The authors built and validated an 8-question stress mindset measure, then showed that short films framing stress as enhancing or debilitating shifted people's scores. Seeing stress as enhancing went with moderate rather than extreme cortisol responses and more willingness to seek feedback.
46 adults drank the same 380-calorie shake twice, once labeled a 620-calorie indulgence and once a 140-calorie sensible choice. The indulgent label brought a steep drop in the hunger hormone ghrelin and the sensible label a flat response, and fullness followed the label rather than the nutrition.
80 adults with irritable bowel syndrome got pills openly described as sugar pills, or the same clinician attention with no pills. After three weeks the open-placebo group reported more overall improvement (5.0 versus 3.9), with symptom severity also favoring the pills.
Hotel room attendants in seven hotels were told their daily cleaning already met exercise guidelines. Four weeks later they saw themselves as more active and had lower weight, blood pressure, body fat, waist-to-hip ratio and BMI than the control group, with no measured change in behavior. It is small and unblinded, which is its weakness.
People randomly assigned to count blessings weekly or daily scored higher on several, but not all, well-being measures than people listing hassles or neutral events. The most consistent change was in positive mood, and physical symptom results were much less consistent.
keep reading
more from the library
the whole person biblical wellness Worship, prayer, Sabbath rest, fasting, gratitude and forgiveness, and what large studies found. the whole person neuroscience The gut-brain axis, the vagus nerve, exercise and the hippocampus, sleep, and what lion's mane has shown in people. the whole person precision wellness Why two people eat the same meal and get different results, and what personalized advice has delivered so far.
This page summarizes published research for education. It is not medical advice, and nothing here describes what any nanonourish™ product does. Talk with your care provider before changing your diet or starting a supplement, especially if you are pregnant, nursing or taking medication. Summaries by Dr. Kaylan Jackson, PhD, a chemist, not a physician. Citations checked against PubMed and Crossref, September 2026.