Doctor Says Intermittent Fasting Shows 0 Proven Health Gains, Carries Risks

1 articles · Updated · American Medical Association · Jun 23

Jennifer Schriever, an obesity-medicine physician, said on the AMA’s latest “Health vs. Hype” podcast that intermittent fasting lacks convincing evidence for better weight loss, heart health or cognition.
Studies comparing fasting with standard calorie restriction show no significant difference in weight loss or metabolic markers, she said; if total calorie intake stays the same, the touted benefits generally do not appear.
Schriever said evidence is also weak for longer life, cancer prevention and cognitive improvement, with high-quality meta-analyses showing fasting is essentially neutral in healthy adults.
Risks are clearer for people with eating-disorder histories, diabetes, older adults and those with low muscle mass, because restricted eating windows can lead to nutrient deficiencies, low blood sugar, sleep disruption and muscle loss.
Her broader message was that long-term weight management depends on sustainable lifestyle changes—healthy diet, exercise and sleep—rather than fasting alone.