Dr Alok Chopra, cardiologist and functional medicine expert, explained that one meal a day rewires a person's "biology for longevity". In OMAD, one fasts for 20-22 hours every other day. Citing MIT study, he revealed it found that a 24-hour fast boosts stem cell production in gut, repairing digestive lining. "Avoid it...if you're pregnant, underweight, recovering from illnesses," he said.