Diet or genetics: Which has a greater impact on lifespan?

A new study reveals that genetics play a larger role than lifestyle in determining lifespan, though lifestyle choices like diet and exercise still have a huge impact on longevity.

In Short

• Genetics seems to play a larger role in determining lifespan
• Despite this, the study showed that caloric restriction was still beneficial
• While we can’t change the genes we inherit, lifestyle interventions could help

A new study has provided fresh insight into the age-old question: what plays a bigger role in how long we live, genetics or lifestyle?

While it's long been observed that people with long-lived parents and grandparents tend to live longer themselves, lifestyle choices such as diet and exercise also play a critical role in extending lifespan.

This latest research highlights how these two factors interact and which one holds more influence over longevity.

The study, published in Nature, which focused on the effects of caloric restriction on lifespan, used 960 genetically diverse mice to examine how different levels of calorie intake affected longevity.

Researchers tested classical models of calorie reduction, feeding the mice either 20% or 40% fewer calories than usual, as well as intermittent fasting models, which mimic popular human dietary trends.

DIET VS GENETICS

The key finding? Genetics seems to play a larger role in determining lifespan than dietary interventions alone.

The longer-lived mice remained longer lived despite the dietary changes, suggesting that "good genes" are critical for longevity. While calorie restriction did improve the lifespan of shorter-lived mice, they still couldn't match their longer-lived counterparts, even with dietary improvements.

Despite this, the study showed that caloric restriction was still beneficial, with mice in the 40% calorie reduction group experiencing increased lifespans compared to those in the 20% group.

However, this extreme diet also came with downsides, such as reduced immune function and muscle loss, which could negatively impact health in a real-world environment.

One important caveat is that it's unclear how directly these findings apply to humans. The control mice were fed as much as they wanted, which is not a perfect reflection of human eating habits.

The 40% calorie restriction group exercised more, possibly due to hunger-driven behaviour, further complicating the relationship between diet, exercise, and lifespan.

Ultimately, while we can’t change the genes we inherit, the study suggests that lifestyle interventions, like balanced diets and regular exercise, can still positively influence how long we live. Genetics may set the foundation, but how we live can make a significant difference too.