Image from flickr user ~db~ under a Creative Commons CC BY-NC-ND 2.0 Licence
Although we still don’t have a good handle on what aging actually is, it’s something many of us wish we could slow down. Lifespan extension is a tricky thing to get good data on, but there is evidence that Caloric Restriction may extend lifespan, it certainly works in mice. But restricting calorie intake by maybe 30% is tough (say a man consuming 1700 calories instead of the standard 2400), I for one haven’t got the willpower for it, have you? So over the last few years, people have tried to come up with alternatives that mimic the biological effects of caloric restriction, but reduce the hunger. Alternatives include intermittent fasting and time-restricted feeding. It is thought that Caloric Restriction may affect aging by activating autophagy, a kind of maintenance machinery in the cell, preventing the accumulation of cellular damage.
In a recent paper in the journal Cell Metabolism, researchers at Albert Einstein College of Medicine, New York and Newcastle University tested whether a “two-meal a day” feeding regime, which was simulated by making food available for just two periods of 2 hours each day. The control mice had food available continually for ad lib feeding. They hoped that the 2 hours a day feeding regime might increase autophagy and effectively mimic caloric restriction.
To being with, the researchers monitored food intake to check that the ad lib feeding mice and the two-meals a day mice consumed a similar amount of food and they did. The two-meal a day mice, however, had altered body composition, with reduced body fat, reduced liver fat, and increased muscular mass.
The researchers then measured the amount of autophagy in the mice, and found that the 2 meals a day mice did in fact show reduced autophagy. They also showed reduced signs of inflammation and an increase in a type of muscle fibre that is typically lost during normal aging. During the first feeding window, the mice were found to have increased autophagy and increased utilization of fat, decreasing the amount of fat in the livers of the mice. In addition, the 2 meals a day mice had improved glucose tolerance. Reduced glucose tolerance is a kind of pre-diabetic state, and the risk of it increases with age, so improved glucose tolerance is a good thing.
In summary, the researchers found that 2 meal a day feeding improved overall health of the mice, however, they didn’t run the study long enough to test whether the feeding regime increased actual lifespan of the mice, which I guess would be a nice thing to test. But the data do suggest that that 2 meals a day does increase “healthspan” – i.e. the mice are healthier as they get older than mice who can eat whenever they want.
So what does this tell us? Although clearly further research is needed, but the data in this paper does suggest that a 2 meal a day feeding regime or other forms of intermittent fasting may increase autophagy and healthspan and this might extend lifespan. Having just 2 meals a day still sounds fairly rough to me, but at least you get a full compliment of calories right, so you get 2 pretty good sized meals. That’s probably more tolerable than eating 30% less. Maybe. Of course, this is a study in mice, so the findings may not translate to people, but the process of aging is pretty similar, so it’s probably got a good chance.