The human gut microbiome consists of trillions of microorganisms, and the composition of the microbiota is different among people who are obese and those with normal body weight. Researchers from Charité–Universitätsmedizin, Berlin, and the University of California, San Francisco, demonstrated that a low-calorie diet significantly alters the gut microbiota composition. Additionally, they found that a low-calorie diet resulted in an increase in Clostridioides difficile, which is associated with antibiotic-induced diarrhea and colitis.

This change in bacterial composition altered the body's energy balance by influencing the absorption of nutrients from the gut. Researchers studied 80 post-menopausal women who ranged from slightly overweight to severely obese for 16 weeks and followed either of the following regimens – A medically supervised meal replacement regime, consuming shakes…