Compared to health-related fasting does fasting on the Jewish High Holiday of Yom Kippur offer unique psychological and social benefits?
New research from Dr. Adam Cohen, and Dr. Kathryn A. Johnson examines how fasting on Yom Kippur impacts wellbeing, and how these effects compare to fasting for health reasons, such as blood sugar regulation or weight management.
Their multi-year study explores whether abstaining from food and drink for religious or spiritually-motivated purposes uniquely cultivates virtues like humility, generosity, and social cohesion, setting it apart from the benefits of intermittent fasting for health. In this episode of the Stories of Impact podcast, they share findings from the study and offer insights from their scientific mission to understand the broader impact of fasting as a ritual.
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Yom Kippur, or the Day of Atonement, is the holiest day in Judaism, often called the Sabbath of Sabbaths. It is a day of fasting, confession, and intensive prayer, centered on three key spiritual elements: repentance (taking responsibility for past wrongs and realigning with moral values), reappraisal (finding meaning in challenges), and recommitment (renewing commitments to personal growth, faith, relationships, and wellbeing).
At Arizona State University, Dr. Adam Cohen, a professor of psychology, and Dr. Kathryn A. Johnson, a research professor, are leading a multi-method, multi-year study on the effects of Yom Kippur fasting on personal and social wellbeing. Supported by the Templeton World Charity Foundation, their research examines whether religious fasting promotes human flourishing.
"When we look at flourishing, it's important to keep in mind that we don't only mean happiness, or life satisfaction, or feeling good about yourselves," says Dr. Johnson. "Positive emotions are important, but I think today, the more nuanced, and really more historical way of looking at human flourishing, is that people do have virtue, people are good to one another. They're living lives for the good of the wellbeing of everyone."
The researchers define flourishing as a combination of virtue (temperance, humility, generosity); subjective wellbeing (social and spiritual connection, life satisfaction); and physical wellbeing.
Their work aims to uncover how fasting—particularly within a religious context—fosters these qualities and contributes to a deeper sense of personal and communal growth.
Over three years, they surveyed Yom Kippur observers, tracking how fasting influenced self-reflection, moral recommitment, and community belonging. Their findings suggest that fasting strengthens interpersonal bonds and fosters humility, reinforcing the idea that religious rituals can serve as catalysts for transformation.
“What we think is really special about this project is that we’ve done this multiple times over multiple years," explains Cohen. "We’ve gotten in touch with the same Jewish people around Yom Kippur each year to ask them, ‘Did you fast?’ and we try to measure all these things about those people. And then we go back to those same people a year later so that we can see over time: Are there any changes?”
As part of their study, Cohen and Johnson also examined how fasting for religious purposes compares to fasting for health reasons—such as weight loss, metabolic health, or intermittent fasting regimens. Their research asks: Does spiritual intention influence self-control, wellbeing, and social connection differently than fasting purely for health?
Cohen explains their approach:
“We're not just trying to understand Jewish fasting—we're trying to understand fasting more generally. If you're fasting for a religious or spiritual reason, does that have the same or different effects than if you're fasting for a health reason? Are the benefits of fasting tied to intention and meaning, or do they extend beyond that?”
By comparing the two, the researchers aim to determine whether the act of fasting itself—or the religious framework surrounding it—plays a greater role in fostering virtues like self-control, resilience, and pro-social behavior.
To assess these effects, the researchers compared fasting to other religious practices, such as attending synagogue services. They found that fasting had a stronger impact on spiritual transformation than communal worship alone. Additionally, those who felt a stronger connection to their religious community were more likely to fast, suggesting that social belonging plays a key role in sustaining religious traditions.
“Fasting actually helps increase flourishing because people sometimes undergo, especially when fasting for religious reasons, a kind of spiritual transformation. Through a time of reflection—Yom Kippur is very focused on repentance—a recommitment to God, a recommitment to the community, also plays into increasing flourishing,” says Johnson.
Beyond religious significance, their research explores fasting’s role in self-discipline. Yom Kippur requires significant self-restraint—abstaining from food and drink for 25 hours—which fosters resilience and goal-directed behavior. Their study examines whether repentance, reappraisal, and recommitment mediate the relationship between fasting and flourishing and how factors like deep self-reflection and religious participation influence that relationship.
Listen in to hear more about their ongoing research.
Tune in to the full episode with the above player and view show notes here.
Learn more about the TWCF-funded project: Fasting and Flourishing: A Comparative Analysis
View TWCF's Science of Religious and Spiritual Exercises priority.
Built upon the award-winning video series of the same name, Templeton World Charity Foundation’s “Stories of Impact” podcast features stories of new scientific research on human flourishing that translate discoveries into practical tools. Bringing a mix of curiosity, compassion, and creativity, journalist Richard Sergay and producer Tavia Gilbert shine a spotlight on the human impact at the heart of cutting-edge social and scientific research projects supported by TWCF.
