How Fasting & Caloric Restriction Impact Health | Dr. Satchin Panda & Dr. Andrew Huberman

Summary

The video discusses a study exploring whether the longevity benefits of caloric restriction are due to reduced calories or timed feeding. Mice on a calorically restricted diet lived 10% longer than controls. However, mice on the same calorically restricted diet timed to their active period lived 20% longer, and mice timed to their normal feeding period lived 35% longer. This suggests the timing of food intake, not just caloric reduction, impacts longevity. In humans though, a small difference in feeding window timing did not impact weight loss. More research is needed, but time-restricted feeding may provide longevity benefits beyond just caloric restriction.

Takeaways

• 😀 Calorie restriction extends lifespan in rodents, but it was unclear if this was due to reduced calories or changes in feeding timing
• 😲 Restricting feeding to only the active cycle extends lifespan even more than continuous calorie restriction
• 🚨 Feeding rodents only during their normal fasting period (equivalent to humans eating only at night) had the biggest impact on longevity - up to 35% longer lifespan
• 🤔 None of the known biomarkers of longevity predicted differences between the feeding regimens
• 🧐 This suggests there are biomarkers linked to timing of feeding and longevity that are still unknown
• 😕 In human studies, time restricted feeding within already habitual 10-12 hour feeding window showed no additional weight loss benefit
• 👍 But this was only a 2 hour daily difference, much less than tests in rodents which vary timing more extremely
• 🤝 When calorie restriction is done within a 12 hour or less window, the precise duration does not change longevity benefit in rodents
• 😉 Interpretations of this human study's results in popular media were often misleading about value of time restricted feeding
• 📝 More research is still needed in humans on potential longevity benefits from changes in feeding timing, not just calorie reduction

Q & A

What was the key finding from Joe Takahashi's 2017 study?

Joe Takahashi's 2017 study showed that most caloric restriction protocols actually create a condition of time-restricted feeding, where mice eat their full daily allotment of food within 2-4 hours.

What methods did Joe Takahashi use in his follow-up study to precisely control mouse feeding?

Joe Takahashi worked with engineers to develop a smart cage that could program how much food is provided to mice at specific times, allowing precise control over caloric intake and feeding/fasting duration.

How much longer did calorie-restricted mice live compared to ad libitum fed mice in Joe Takahashi's study?

Calorie-restricted mice that ate small frequent meals lived 10% longer than ad libitum fed mice. Calorie-restricted mice that ate within a 12 hour window lived 20% longer. And calorie-restricted mice that ate only during their active/nighttime cycle lived 35% longer.

What impact would a 35% increase in lifespan potentially have for humans?

A 35% increase relative to an average human lifespan of around 80 years would equate to an additional 25-35 years of life.

Did known biomarkers of longevity predict differences between calorie-restricted feeding groups in Joe Takahashi's mouse study?

No, known biomarkers like A1c, cholesterol etc. did not predict differences in longevity between the calorie-restricted mouse groups in Joe Takahashi's study.

What were the feeding windows used in the human time-restricted feeding study discussed?

Participants habitually ate in a 10 hour window. One group did 25% CR in a 10 hour window. The intervention group did 25% CR restricted to an 8 hour window.

Why did the human study likely show no additional weight loss from time restriction?

The human study compared 10 vs 8 hour feeding windows. Prior mouse research shows no major differences within 12 hour windows, so a small 2 hour reduction likely wasn't enough to further impact weight.

What appears most important for achieving benefits of caloric restriction in mice?

Consuming a sub-maintenance calorie level appears most important. The exact duration of feeding window doesn't change weight or longevity biomarkers as long as it's under 12 hours.

Might time-restricted feeding provide benefits for humans beyond just weight loss?

Yes, time-restricted feeding may provide various health benefits for humans distinct from and in addition to potential impacts on weight loss.

Would humans likely see 35% lifespan extension from time-restricted feeding as the mice did?

It's not clear. More research is needed, but even a fraction of that potential increase would be profound.