One thing 'helps you live longer' as expert slams fasting

New research, presented in the journal Nature, made an unexpected finding: the mice that lived longest under calorie-restricted diets were those that maintained their weight despite eating less food

A new study has found that eating less could be more beneficial for longevity than periodic fasting.

Scientists have discovered that reduced calorie intake had a more significant effect on extending life expectancy than fasting. The research highlighted a "more moderate" level of reducing calories may be the better way to aid long-term health and a longer life. The American research, presented in the journal Nature, made an unexpected finding: the mice that lived longest under calorie-restricted diets were those that maintained their weight despite eating less food.

In contrast, the mice with the greatest weight loss from restricted diets appeared to experience diminished energy, weakened immune and reproductive systems, and ultimately led shorter lives.

The enduring mystery has been why such restrictive diets prolong life and how this could be applied to humans, given that almost a century of laboratory studies have consistently observed that eating less frequently or reducing food consumption leads to a longer lifespan in animals.

Scientists at The Jackson Laboratory (JAX) in Bar Harbor, Maine, addressed this puzzle by following the health of over 900 genetically diverse mice on various diet regimens, thereby reflecting the genetic variety seen in human populations.

Again this study found low-calorie diets extended the lives of the mice regardless of their body fat or blood sugar levels. It again pointed to the idea that restricting calories could be more beneficial for longevity than intermittent fasting.

Professor Gary Churchill from JAX highlighted the significance of the findings, stating: "Our study really points to the importance of resilience. The most robust animals keep their weight on even in the face of stress and calorie restriction, and they are the ones that live the longest."

Prof Churchill and his team put female mice on various diets, including unrestricted eating, daily calorie reductions to 60% or 80%, and intermittent fasting with one or two days without food each week.

The mice were then monitored until the end of their natural lives, undergoing regular health checks. Results showed that while mice on an unrestricted diet lived around 25 months, those on intermittent fasting reached about 28 months, those consuming 80% of their usual intake lived up to 30 months, and those on a 60% calorie diet lived the longest at 34 months.

Despite the groups, there was a broad range of lifespans, with mice consuming the least calories living anywhere from a few months to 4.5 years. The research team discovered that genetic factors had a "far greater" influence on lifespan than diet when they analysed their data to explain this wide range.

They suggest that their findings emphasise the significant role of yet-to-be-identified underlying genetic features in determining how these diets would impact an individual's health trajectory.

The team identified genetically-encoded resilience as a "critical" factor in lifespan; mice that naturally maintained their body weight, body fat percentage and immune cell health during periods of stress or low food intake, as well as those that did not lose body fat late in life, lived the longest.

Prof Churchill stated: "If you want to live a long time, there are things you can control within your lifetime such as diet, but really what you want is a very old grandmother."

The study also questioned traditional beliefs about why some diets prolong life. For instance, factors such as weight, body fat percentages, blood glucose levels and body temperature did not explain the connection between calorie restriction and longevity.

The study discovered that traits linked to red blood cells and immune system health have a stronger connection to lifespan. The researchers suggest that human longevity studies, which frequently use metabolic measurements as ageing or youthfulness indicators, might be missing key elements of healthy ageing.

Prof Churchill said: "While caloric restriction is generally good for lifespan, our data show that losing weight on caloric restriction is actually bad for lifespan. So when we look at human trials of longevity drugs and see that people are losing weight and have better metabolic profiles, it turns out that might not be a good marker of their future lifespan at all."