A study by Stephen Spindler won the first Methuselah Foundation MPrize (also known as the Methuselah Mouse prize) for rejuvenation based on research into caloric restriction (CR), which is the idea that by eating less calories, but enough to avoid malnutrition, you can extend your life by 42%.
The study, published in 2004, applied CR to a group of mice that were aged 19 months. Within two months, the mean time to death started increasing (the mice died off slower than normal).
After the final mouse died, the numbers revealed that the average lifespan had been increased by 4.7 months over the usual longevity of that breed of mouse (male mice of breed B6C3F1, average lifespan 1000 days; 32.9 months), and the oldest mouse died 6 months over the usual.
The equivalent in human terms is an increase of about 10 years.
Additionally, it was found that CR delayed the onset of tumours until much later than in the control mice.
Human trials have been undertaken a few times since then. We live much longer than mice, though, so it’s hard to measure the longevity benefits, but a two year test of CR showed a marked decrease in tumour incidence, which is similar to what we see in mice. The 2015 report by the Gerontological Society of America concluded that CR was a tool worth using for non-obese humans.