Calorie Restriction May Slow Aging by Preserving Telomeres

Research suggests that calorie deficits affect health during aging. Primary aging is the innate process that all people experience; secondary aging is the acceleration of the aging process by excess food intake, lack of exercise, and disease.It is this secondary aging that may be affected by diet, and animal studies have found that restricting calorie intake can slow the process, reduce disease, and prolong life. Although several mechanisms have been proposed to explain this effect, there is no firm evidence showing why caloric restriction might prolong life. 

As cells age, telomeres, the protective lengths of DNA at the ends of chromosomes. One study has shown that caloric restriction slows the shortening of telomeres and prolongs lifespan. Researchers found that, initially, caloric restriction accelerated telomere shortening, but after a year, it began to slow the process. At the end of 2 years, the calorie-restricted and control group had lost similar telomere length. This trial recruited 220 participants, of whom 175 were included in this data analysis. All participants were aged between 21 and 50, healthy, and had a body mass index (BMI) of between 22 and 28 kilograms per square meter (kg/m2), indicative of healthy weight to overweight. 

Two-thirds of participants committed to a 25 % calorie restriction for 24 months with rest as controls who continued their regular diet. The researchers advised all participants to undertake moderate exercise for 30 minutes at least five times a week but keep their activity levels the same during the course of the 2-year study. They provided meals to those in the caloric restriction group for the first 27 days to help them with food selection and portion size to ensure adequate intake of essential nutrients throughout the study. Throughout the study, the average calorie restriction fell short of the 25% aim, with participants achieving a mean reduction of 11.9%. 

At the start and every two weeks throughout the study, the researchers recorded the weight of all participants. During the first 12 months, those on caloric restriction lost weight, and then their weight stabilized over the next 12 months. Anyone whose BMI went below 18.5 (underweight) discontinued the study. 

The researchers measured telomere length from blood samples taken at the start of the study, at 12 months, and 24 months. They found that in the first 12 months, telomere length decreased faster in people on caloric restriction. In the second year, the decrease rate slowed to a lower rate than that of control subjects.