What the Evidence Says
All that said, dry fasting by any other name remains dry fasting. “Abundant” evidence from animal studies suggests the potential of various types of fasting for disease prevention and treatment in humans, noted the authors of the consensus report, Along with the risks described above, small studies have explored short-term effects in people, all of which have yet to be established by larger and longer-term studies.
In a recent small study, researchers at Baylor College of Medicine, Houston, Texas, reported that dawn-to-dusk dry fasting for 30 days reduced levels of inflammatory cytokines in the 13 participants with a high body mass index. Earlier work by the group showed that dawn-to-dusk dry fasting for 30 days induced “anti-atherosclerotic, anti-inflammatory, and anti-tumorigenic proteome” in peripheral blood mononuclear cells of 14 individuals with metabolic syndrome (The researchers declined to comment for this article.)
Importantly, the health effects can vary among individuals for unknown reasons, found a recent cross-sectional study of fasting blood glucose (FBG) changes in 181 patients with type 2 diabetes during Ramadan intermittent fasting (RIF), which involves dry fasting during daylight hours for 1 month. The researchers classified participants into three groups: reduced average FBG levels (44%), no change in FBG levels (24%), and increased FBG levels (32%). The authors wrote that further studies are needed to identify factors associated with the differences and to identify “those who are great candidates for RIF.”
In contrast to some of the concerns expressed by clinicians, an exploratory study of daytime dry fasting among 34 healthy Baha’i volunteers in Germany concluded that the 19-day regimen “is safe, has no negative effects on hydration, can improve fat metabolism and can cause transient phase shifts of circadian rhythms.” The authors acknowledge that a larger number and more diverse participants are needed to validate the findings and assess the impact on long-term health.
What to Advise Patients
For patients who want to fast as part of their weight loss regimen or to help manage diabetes, clinicians can consider suggesting “alternate ways of eating that might achieve similar goals,” Ms. Bader said. One is intermittent fasting without dry fasting: the 16:8 method (16 hours of fasting, 8 hours of eating) or the 5:2 method (normal eating for 5 days, reduced calorie intake for 2 days), which can support improved insulin sensitivity and metabolic health.
Caloric restriction can also work if the patient maintains a balanced diet that includes all essential nutrients, she said. A low-carbohydrate diet that focuses on limiting carbohydrate intake while increasing consumption of lean proteins and healthy fats has been shown to lower blood sugar levels and improve insulin sensitivity.
Other healthy strategies for patients include the Mediterranean diet, which emphasizes whole grains, fruits, vegetables, nuts, seeds, olive oil, and lean proteins such as fish, or a similar plant-based diet with less animal protein. Ms. Bader advises cultivating mindful eating, which involves paying attention to hunger and fullness cues, making thoughtful food choices, and focusing on being present during meals.
“Each of these dietary strategies offers potential benefits for managing type 2 diabetes and improving overall health,” Ms. Bader said. “I have not had any patients who have tried dry fasting specifically. However, I have encountered scenarios where individuals abstained from food and beverages due to religious practices. In those cases, we focused on ensuring that they maintained proper hydration and balanced nutrition during their eating periods to manage their diabetes effectively and prevent complications.”
Overall, Dr. Adimoolam suggests that clinicians help patients find a weight-loss plan that works best for them based on understanding the calories in the foods they like and don’t like. For fasting regimens, patients can be encouraged to choose one with fluids when possible, as well as intervals of time to fast and eat that work best for their lifestyle.
Ms. Bader, Dr. Bruno, and Dr. Adimoolam report no relevant conflicts.
A version of this article appeared on Medscape.com.