New study suggests nighttime fasting may increase longevity

A new study using fruit flies has demonstrated that intermittent fasting may help slow the aging process. The research was completed by researchers from Columbia University and published in September 2021 in the Journal Nature. Intermittent fasting is a feeding pattern that alternates between periods of eating and fasting. It basically limits food intake, not overall caloric intake, to specific hours within a day. This is different from dietary restriction, which reduces caloric intake and has also been shown to increase longevity. Proponents of intermittent fasting may sometimes refer to it as the 5:2 diet or the 16/8 method. Historically, fasting was done for cultural and religious reasons. But it has now become a popular way to lose weight because you don’t have to change what you eat (just when you eat). Celebrities such as Beyoncé, Nicole Kidman, and Hugh Jackman are just a few among many famous people who swear by the weight loss benefits of intermittent fasting. Science has also demonstrated the usefulness of this practice, with studies showing that fasting two days per week or restricting daily eating to an eight-hour window contributes to weight loss. Several past studies have demonstrated that intermittent fasting has other benefits outside of weight loss, including inducing cellular repair and increasing longevity. The new research investigated how intermittent fasting works inside cells to slow the aging process and explored the role that circadian rhythm played in its efficiency. “Because intermittent fasting restricts the timing of eating, it’s been hypothesized that natural biological clocks play a role,” said Dr. Mimi Shirasu-Hiza, the study’s lead author and an associate professor of genetics and development at Columbia University. The researchers used fruit flies in the experiment, whose biological clock resembles that of humans (staying active during the day and sleeping at night). Fruit flies – a household pest that is attracted by fermenting fruits and vegetables – also age in a similar way to humans (despite living for only two months) and share about 70 percent of human disease-related genes. The team grouped the flies into four different feeding schedules: 24-hour unrestricted food access, 12-hour daytime food access, 24-hour fasting followed by 24-hour unrestricted food access, or intermittent Time Restricted Feeding (20 hours of fasting followed by a full day of unlimited feeding). Interestingly, the flies in the iTRF (intermittent Time Restricted Feeding) group recorded a significant extension of lifespan (18% extension for females and 13% for males). Additionally, lifespan increased only for those flies that fasted at night and broke the fast around lunchtime. There was no longevity advantage for flies that fasted all day and only ate at night. Based on these findings, the researchers established that a cellular cleaning process known as autophagy was activated only when fasting took place at night. “We found that the life-extending benefits of iTRF require a functional circadian rhythm and autophagy components. When either of those processes were disrupted, the diet had no effect on the animals’ longevity,” added Dr. Shirasu0-Hiza. In addition to the longevity advantage, iTRF was also found to improve the fruit flies’ “healthspan” by reducing age-related protein aggregation, enhancing muscle and neuron function, and delaying the onset of aging markers in intestinal tissues and muscles. The team now suggests that based on the outcome of this study, it may be possible to create a pill that stimulates the same cleaning process and benefits as iTRF – but without the hunger pangs. “Any type of restricted eating is difficult. It requires a lot of discipline, and most studies of time-restricted fasting in humans have built in a cheat day to make it more tolerable. It would be much easier to get the same health benefits if we could enhance autophagy pharmacologically, specifically at night,” said Dr. Matt Ulgherait, an associate research scientist at Columbia who also contributed to the research.