Hunger or cold?

The relationship between calorie restriction, body temperature and life expectancy

Anna Yudina, "Scientific Russia"

Scientists have found out how limiting the number of calories and lowering body temperature are associated with life expectancy, according to a press release from Scripps Research Linking calorie restriction, body temperature and healthspan.

Article by Guijas et al. Metabolic adaptation to calorie restriction is published in the journal Science Signaling – VM.

Cutting calories significantly may not be an easy task for most, but it is associated with a host of health benefits, ranging from increased life expectancy to a lower chance of developing cancer, heart disease, diabetes and neurodegenerative conditions such as Alzheimer's disease.

A new study conducted by teams led by Scripps research professors Bruno Conti and Gary Suzdak sheds light on the important role that body temperature plays in realizing these diet-related health benefits. Thanks to their discoveries, scientists are paving the way for the creation of a medicinal compound that mimics the valuable effects of lowering body temperature.

Conti has spent years researching how and why calorie restriction leads to better health, with the ultimate goal of translating the findings into medications that can mimic what happens naturally when a person eats less.

One constant observation is that when mammals consume less food, their body temperature drops. Conti explains that this is an evolutionary way to help us conserve energy until food becomes available again. This makes sense considering that up to half of what we eat every day is converted into energy just to maintain our body temperature.

Conti's previous work has shown that lowering temperatures can increase life expectancy regardless of calorie restriction – and that these effects include activation of certain cellular processes, most of which have yet to be identified.

On the other hand, studies have shown that preventing a drop in body temperature can actually counteract the positive effects of calorie restriction. Notably, in an experiment involving calorie-restricted mice, the anti-cancer benefits were reduced when the internal body temperature remained the same.

"It's not easy to determine what contributes to positive changes in calorie restriction," says Conti. – Is it a decrease in calories by itself or a change in body temperature that usually occurs when a person consumes fewer calories? Or is it a combination of both?"

In the new study, Conti and his team developed an experiment that would allow them to independently assess the effects of reduced nutrients and body temperature.

They compared one group of calorie–restricted mice kept at room temperature -about 68 degrees Fahrenheit (22 degrees Celsius), with another group kept at 86 degrees (30 degrees Celsius). The warmer environment caused "thermoneutrality" – a condition in which it is not easy for most animals to lower their body temperature.

The researchers, using a technology they developed called activity metabolomics, then evaluated the mice by measuring their metabolites– chemicals released during metabolism. Thanks to this, they were able to search in the bloodstream and in the brain for molecules that change due to a decrease in nutrient content or body temperature.

"The data we collected showed that temperature has the same or greater effect on metabolism than nutrients during calorie restriction," says Conti. It is noteworthy that the team presented the first comprehensive profiling of metabolites that change with a decrease in temperature.

Using computer analysis of the results obtained on both groups of mice, the scientists were able to determine which metabolites are most responsible for the change in body temperature. In a separate experiment, they also showed that it is possible to inject certain metabolites as a drug that affects body temperature.

Conti says further work to test changes caused by temperature during calorie restriction should provide new targets for future medications, which he calls "temperature copycats" that can have beneficial effects without the need to lower body temperature.

Portal "Eternal youth" http://vechnayamolodost.ru