As millions of Christians around the world fast in the weeks leading up to Easter, new research from Greece suggests that this ancient religious practice may bring significant health benefits. A recent study led by Konstantinos Rouskas at the Biomedical Sciences Research Center “Alexander Fleming” links seasonal abstinence from animal products—common during Greek Orthodox Easter fasting—to positive changes in the body’s metabolism and blood chemistry.
The findings reveal that short periods of dietary restriction, especially the kind practiced for spiritual reasons may do more than nourish the soul. They may also help lower disease risk and promote healthier aging.
The study, published in “npj Metabolic Health and Disease”, tracked over 400 adults from Thessaloniki, Greece. About half of the participants followed a traditional Greek Orthodox dietary pattern—one that includes fasting from meat, dairy, and eggs for roughly half the year. The other half ate a typical omnivorous diet throughout the year.
Researchers analyzed blood samples from both groups at two points in time: once during a period when both groups ate normally, and again during Lent, when the fasting group was avoiding animal products.
Blood tests indicated that individuals observing the religious fast exhibited reduced levels of substances associated with heart disease, including “bad” cholesterol and saturated fats. Additionally, levels of amino acids typically found in meat decreased. These particular amino acids have been linked to obesity and an elevated risk of diabetes.
The most significant change was an increase in a hormone called FGF21. This hormone plays a role in how the body handles fat and sugar. In animals, higher levels of FGF21 are linked to longer life and better metabolism. Though its exact role in humans is still being studied, its rise during fasting indicates potential health benefits.
The dietary pattern of Greek Orthodox fasting shares similarities with a vegan diet. During fasting periods, followers avoid meat, fish, dairy, and eggs, though some seafood like shellfish is allowed.
Researchers compared their results to past studies on veganism and found strong overlap. More than 80% of the metabolic changes seen during fasting matched those found in full-time vegans.
However, unlike vegans, the fasting group eventually returned to eating animal products. This allowed researchers to observe how quickly the body responded to diet changes. They found that even short-term restrictions led to noticeable shifts in blood chemistry.
While the fasting periods lasted just a few weeks, the changes in metabolism were swift and significant. The researchers stress that these changes may be temporary and tied to the period of restriction. Still, the findings point toward how even brief diet adjustments can impact health.
A score used to estimate the overall risk of death—based on 14 different blood markers—dropped during fasting. This score remained the same for individuals who did not fast. The change suggests that the temporary diet switch improved markers associated with long-term survival.
“As we journey through this sacred season of Lent, may our hearts be renewed with faith, our minds focused on reflection, and our lives filled with compassion and grace. Let us embrace this time of prayer, fasting, and almsgiving as we prepare for the joy of Easter.” pic.twitter.com/naFo7XYLdN
— David Anil Sharmak (@anilvideo_houze) April 8, 2025
The team also looked at nearly 1,500 proteins in the blood. These proteins affect everything from immune response to hormone balance. In the fasting group, more than 250 proteins changed during the restricted period. One of the standout findings was the sharp rise in FGF21, mentioned earlier.
Interestingly, about a quarter of the proteins affected by fasting are targets of existing drugs. This includes medicines for conditions like heart disease, diabetes, and cancer. This opens the door to future research on how food and medicine can work together to improve health.
Eight proteins changed the most during the fasting period. These include those linked to metabolism, immune response, and inflammation. Several of them—such as OXT, FOLR2, and HAVCR1—are already being studied in clinical trials for new treatments.
HAVCR1, for example, is linked to kidney repair and inflammation. Its levels decreased during fasting, which could indicate reduced strain on the kidneys or less inflammation. Another protein, OXT, influences social behavior and appetite, but it also may affect stroke risk.
FGF21 remains the most notable hormone. Produced by the liver, it may help regulate energy and has shown promise in early drug trials for obesity and diabetes. Its rise during fasting, along with a drop in an enzyme that breaks it down, may enhance its effects.
While the study highlighted many positives, it also noted some potential downsides. Increased levels of certain hormones could affect bone health over time. Also, one protein (OXT) was linked to higher stroke risk, although more research is needed to confirm this.
Earlier research has found that vegetarians may face a slightly higher risk of stroke. Some experts suspect that low levels of certain nutrients, such as vitamin B12, could play a role. The current study suggests that similar effects might occur during long fasting periods if the diet lacks balance.
