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Short Summary
Main recommendation: Do not conclude from the new JACC study that intermittent fasting is dangerous, because the study concerns skipping breakfast in general, not intermittent fasting. The speaker argues that participants who skipped breakfast also had poor lifestyles, so the findings cannot be attributed to fasting itself.
Key Points
- The study, published in JACC and conducted at the University of Iowa, surveyed 6,550 Americans aged 40 to 75 from 1988 to 1994 about how often they ate breakfast.
- Skipping breakfast was associated with an 87 percent increase in cardiovascular mortality, along with higher risks of obesity, high cholesterol, high blood pressure, type 2 diabetes, metabolic syndrome, and heart disease.
- Breakfast skippers in the study commonly smoked, drank, were physically inactive, and ate poor-quality diets, so these lifestyle factors are a major confounder.
- Skipping breakfast is not the same as intermittent fasting, which the speaker says is typically practiced by people eating well, staying active, and following structured timing.
Details Worth Noting
- The study's survey asked whether people ate breakfast every morning, a couple of days a week, or only sometimes, so it measured habit rather than a controlled fasting intervention.
- The speaker notes the study's conclusion explicitly says it supports the benefits of eating breakfast for cardiovascular health, which he presents as the study's own framing.
- The speaker frames the study as contradicting his usual teaching on intermittent fasting, which is why he analyzes it at length.
- The speaker's claim that the study has "no bearing" on intermittent fasting is his interpretation; the transcript does not report any analysis that separated fasting practitioners from other breakfast skippers.
Bottom Line
The study's findings about breakfast skipping are confounded by poor lifestyle habits, so they should not be read as evidence that intermittent fasting causes death.
