Five-Day At-Home Modified Fasting Trial Reports Short-Term Benefits

Key Takeaways

• The modified fasting program was associated with greater short-term weight loss than the control condition.
• Blood pressure showed no significant change at fasting completion and was lower after food reintroduction in both systolic and diastolic comparisons.
• Secondary analyses showed metabolic, inflammatory, well-being, and gut-microbiome changes, while gut-microbiome and blood-metabolome differences were no longer statistically different at one month, and the authors concluded the program was safe.

In a randomized trial of 64 healthy participants, a five-day, at-home, hypocaloric, ketogenic modified fasting program produced greater short-term weight loss than usual eating, with weight change of -0.52 ± 0.03 kg versus -0.03 ± 0.02 kg (p < 0.001). The intervention provided about 600 kcal per day during the five-day home-based period.

The two-arm randomized controlled trial assigned 32 participants to modified fasting and 32 to a control group that maintained usual eating behavior and lifestyle. Body weight and blood pressure were the prespecified primary endpoints, with secondary measures spanning ketosis, glucose and lipid metabolism, inflammatory markers, antioxidant capacity, and well-being. Assessments occurred at baseline, at the end of fasting, after reintroduction of food, and one month later.

Blood pressure did not change significantly by the end of the fasting period despite the between-group difference in short-term weight loss. After food reintroduction, systolic pressure changed by -0.56 ± 0.12 mmHg versus -0.16 ± 0.12 mmHg, with p < 0.05. Diastolic pressure changed by -0.36 ± 0.08 mmHg versus -0.01 ± 0.08 mmHg, with p < 0.01.

Secondary analyses showed reduced glucose levels and coagulation factors, along with a significant improvement in physical well-being during the five-day intervention. Blood metabolomics indicated a significant decrease in markers of chronic inflammation across the intervention period. Gut metagenomics identified changes in 11 bacterial species and 52 carbohydrate-active enzymes, adding microbial context to the metabolic findings.

By one month, differences in the gut microbiome and blood metabolome were no longer statistically different from the control group. The authors concluded that the program was safe and transiently improved cardiometabolic health and physical well-being in healthy individuals.