Time-Restricted, Calorie-Restricted Feeding
In modern dietary culture, intermittent fasting continues to grow in popularity along with the body of scientific evidence behind it. Variations of the method are also under investigation, including time-restricted feeding (TRF), which involves a longer daily fasting period. Preliminary studies have found that TRF can improve cardiometabolic health in rodents and humans, while caloric restriction (CR) has been associated with elongated lifespan.
Evidence supporting these findings is scarce, yet the timing of calorie restriction may contribute to life-extending effects due to the circadian system and its control of physiology, metabolism, and biological aging cycles.
To investigate this hypothesis, a team of researchers at the University of Texas Southwestern Medical Center in Dallas, TX, conducted a study on mice controlling both their caloric intake and the timing of their meals. The subjects were split into six groups to determine whether meal timing had an independent effect on lifespan. One group served as the control cohort, while the remaining five consumed meals on varying feeding schedules.
Impact on Lifespan
As anticipated, caloric restriction extended the lifespan by an estimated 10% – irrespective of meal timing. The control mice that ate when and as they pleased had a median lifespan of 800 days, compared with 875 days for mice on a calorie-restricted diet.
Mice on the calorie-restricted diet that only ate during the day or the inactive phase of their circadian cycle and spent the remaining 12 hours fasting overnight had a median lifespan of 959 days – nearly 20% longer than the controls.
Calorie-restricted mice that only ate during their active phase and fasted during their inactive phase lived the longest. This group averaged a lifespan of 1,068 days which was almost 35% longer than the control mice.
Anti-Aging Benefits of Calorie-Restricted Meal Timing
The study also revealed that calorie-restricted diets could improve the animals’ regulation of glucose levels and insulin sensitivity – important healthy aging markers – with the greatest improvements reported in mice that only ate during their active phase.
In all mice, aging increased inflammatory activity and decreased gene activity in metabolism and circadian rhythms. While caloric restriction slowed age-related changes, mice that only ate during their active phase showed the most significant improvements.
Limitations and Future Implications
Sleep disruption in mice that ate during their inactive phase may have been a study limitation and could have contributed to their shorter lifespan. Additionally, all studied mice were male, and thus the findings do not account for possible ovarian hormone protection against circadian disruptions. Finally, the animal model of the study may not translate to humans.
The researchers also discussed the possible development of drugs that could target circadian genes to mimic the anti-aging effects of calorie-restricted, strategically-timed dietary patterns. If the latest findings were replicated in large-scale, well-designed human studies, this knowledge could introduce a new aspect for consideration in longevity-oriented nutrition and transform current approaches to anti-aging dietary interventions.
Learn more about the clinical applications of fasting for whole-body health and hormone optimization from Rafael Gonzalez, Ph.D., scientific advisor of the leading nutri-technology company, L-Nutra, during his most recent webinar, available here.
