Effects of intermittent feeding upon body weight and lifespan in inbred mice: interaction of genotype and age.
Level 5 - mechanism / opinion, no new human data
Preclinical animal experiment
PubMed 2402168 · doi:10.1016/0047-6374(90)90107-q
What was done
Male mice from two inbred strains (A/J and C57BL/6J) and their F1 hybrid (B6AF1/J) were placed on either a standard ad libitum diet (4.2 kcal/g) every day or an intermittent feeding regimen of ad libitum access every other day. The dietary regimens were initiated at three distinct ages: 1.5, 6, or 10 months. The authors evaluated the effects of the intervention on body weight, mean lifespan, and maximum lifespan across genotypes and starting ages.
What was found
The abstract does not report exact numerical values or variance metrics, describing direction and statistical significance: - In C57BL/6J and B6AF1/J hybrid mice, initiating alternate-day feeding at 1.5 or 6 months reduced body weight and increased both mean and maximum lifespan compared to ad libitum controls. When initiated at 10 months, body weight was reduced and maximum lifespan increased, but mean lifespan was not significantly altered. - In A/J mice, initiating alternate-day feeding at 1.5 months did not reduce body weight relative to controls but increased mean and maximum lifespan. Initiation at 6 months caused weight reduction at certain ages without significant effects on mean or maximum lifespan. Initiation at 10 months caused no relative weight reduction and decreased both mean and maximum lifespan.
Why it matters
This study demonstrates that the longevity response to intermittent fasting is not uniform across genetic backgrounds or ages of initiation, showing that dietary restriction can be ineffective or even detrimental when started late in life in specific genotypes.
Limits
Findings are from male mice of specific inbred strains and cannot be directly translated to female mice or humans. The abstract does not provide sample sizes, quantitative lifespan measurements, or caloric intake adjustments. Specific causes of death and physiological mechanisms behind genotype-specific lifespan shortening were not reported.
Cited by
- partial In mice, alternate-day intermittent fasting extends lifespan to the same extent as 30% caloric restriction without resulting in a permanent reduction in body weight.