Eating fewer calories can extend your life — but there’s a catch

Who moved their cheese?

A major new study that subjected mice to a variety of diets found that genetic factors had a far greater effect on their lifespan than eating habits.

“If you want to live a long time, there are things you can control over your lifetime, like diet, but really what you want is a very old grandmother,” said study leader Gary Churchill of the Jackson Laboratory. a biomedical research institution.

For the research, nearly 1,000 genetically diverse mice were assigned one of five diets:

• Eat any amount of food at any time
• Consume only 60% of their basic calories each day
• Consume only 80% of their basic calories each day
• They can’t eat one day a week, they can eat as much as they want the other days
• Can’t eat for two days in a row every week, can scarf as much as they want the other days

Mice were given periodic blood tests as they were evaluated for the rest of their lives.

Mice on the unrestricted diet lived an average of 25 months, while those on the intermittent fasting diet lived about 28 months.

Mice that ate 80% of their basal calories lived about 30 months, while those that consumed 60% of their basal lived for 34 months.

Life spans varied within each group—for example, the mice that consumed the fewest calories lived anywhere from a few months to 4 1/2 years.

The researchers determined that very low-calorie diets generally extended the lifespan of mice, regardless of their body fat or blood glucose levels.

However, the study authors were surprised to find that mice that lived longer on the restrictive diets lost the least amount of weight – despite eating less.

Mice that lost the most weight on these diets tended to have low energy, weakened immune and reproductive systems, and shorter lifespans.

“While calorie restriction is generally good for longevity, our data shows this losing weight calorie restriction is actually bad for longevity,” Churchill explained. “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 may not be the case at all a good indicator of their future longevity.”

Churchill’s team identified genetically encoded resilience as a key factor in longevity, noting that mice that naturally maintained their weight, body fat percentage and immune cell health even in the face of stress and calorie restriction, as well as mice that did not. lost body fat late in life, survived longer.

Churchill said the results, published Wednesday in Nature, “suggest that a more moderate level of calorie restriction may be the way to balance long-term health and longevity.”

The research team found that immune system health and traits related to red blood cells were more clearly related to life expectancy than weight, body fat percentages, blood glucose levels and body temperature.

Genetic characteristics, yet to be identified, play an important role in how diets affect a person’s health trajectory, the researchers said.

The study comes as intermittent fasting and extreme weight loss through weekly injections like Ozempic have become popular for staving off obesity and possibly slowing aging.

Emily Feivor, a registered dietitian at Northwell Long Island Jewish Forest Hills Hospital, said more than just a lifestyle intervention — not just healthy eating — is needed for good health.

“Exercise and a balanced diet are definitely supreme when it comes to improving overall health,” Feivor, who was not involved in the new research, told The Post. “Calorie restriction may not be for everyone, as it can increase your risk for malnutrition and other health issues, and should be discussed with your medical provider.”