Researchers at the Icahn School of Medicine at Mount Sinai Medical Center reported that skipping breakfast can trigger a brain response that weakens immune function. The findings were published in the journal Immunity.
The study followed two groups of mice. One group received breakfast as soon as they woke, while the other group skipped it. Blood samples were collected from both groups immediately upon waking, then four hours later, and again eight hours later.
A striking contrast emerged in the samples taken right after waking. In particular, the number of monocytes, a type of white blood cell produced in the bone marrow, showed a dramatic drop. Four hours after waking, mice that did not eat breakfast exhibited roughly a 90 percent reduction in circulating monocytes. Monocytes are essential for defense against infections and also play roles in cardiovascular health and cancer biology.
Further analysis revealed that in hungry mice, monocytes tended to retreat back into the bone marrow to hibernate while new cell production in the marrow slowed down. At the same time, monocytes aged abnormally, even though their lifespan appeared longer due to this hibernation. Rather than mounting a robust immune response, these altered monocytes contributed to systemic inflammation, reducing the body’s resistance to infection.
Biologists also identified specific brain regions that regulate the monocyte response during fasting. Existing research has highlighted potential benefits of short-term fasting, such as weight management and improvements in glucose control for some individuals. The Mount Sinai study adds a layer of detail by suggesting there can be immune-related side effects linked to fasting, which may help researchers understand both benefits and risks of this dietary approach for different populations.