What happens to your stress hormones when you skip a day of eating?
Effect of the one-day fasting on cortisol and DHEA daily rhythm regarding sex, chronotype, and age among obese adults
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Cortisol amplitude increased by 11% without a rise in total daily exposure.
Most assume fasting increases overall stress hormones—but here, the body amplified the rhythm’s intensity without increasing total output, suggesting a recalibration, not overload.
Practical Takeaways
If you're a woman or a morning person, try fasting in the morning—not at night—to align with your natural cortisol shift and avoid sleep disruption.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Cortisol amplitude increased by 11% without a rise in total daily exposure.
Most assume fasting increases overall stress hormones—but here, the body amplified the rhythm’s intensity without increasing total output, suggesting a recalibration, not overload.
Practical Takeaways
If you're a woman or a morning person, try fasting in the morning—not at night—to align with your natural cortisol shift and avoid sleep disruption.
Publication
Journal
Frontiers in Nutrition
Year
2023
Authors
Martyna Marciniak, M. Sato, R. Rutkowski, A. Zawada, Aldona Juchacz, D. Mahadea, M. Grzymisławski, A. Dobrowolska, E. Kawka, K. Korybalska, A. Bręborowicz, J. Witowski, D. Kanikowska
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Going without food for 24 hours can increase the daily fluctuation of cortisol levels, and doing this every day may change how the body's stress response system functions over time.
As obese adults age, their body's daily rhythm of DHEA hormone production becomes weaker, peaks later in the day, and shows lower overall levels, even when fasting, suggesting this change is linked to aging itself rather than metabolic state.
In obese adults, a 24-hour fast is linked to changes in the daily pattern of cortisol release, including a higher peak level and an earlier timing of that peak, while total cortisol production over the day remains unchanged.
In obese adults, a 24-hour fast is linked to a 11% increase in the average daily level of DHEA hormone, without changing the peak timing or overall range of its daily fluctuation. This suggests the adrenal glands may produce DHEA at a higher average rate during fasting, even if total production remains unchanged.
In obese adults, a 24-hour fast shifts the peak time of the stress hormone cortisol earlier by about 42 to 57 minutes in those who naturally wake up early, but does not change the timing in those who naturally stay up late. This suggests that a person's internal body clock affects how their cortisol rhythm responds to fasting.