Individuals capable of reaching the extreme limit of human life such as centenarians are characterized by an exceptionally healthy phenotype-that is, a low number of diseases, low blood pressure, optimal metabolic and endocrine parameters, and increased diversity in the gut microbiota-and they are epigenetically younger than their chronological age. We present data suggesting that such a remarkable phenotype is largely similar to that found in adults following a calorie-restricted diet. Interviews with centenarians and historical data on the nutritional and lifestyle habits of Italians during the twentieth century suggest that as children and into adulthood, centenarians lived in an environment that was nonobesogenic, but at the same time the environment did not produce malnutrition. Centenarians appear to be creatures of habit, and we argue that their habit of eating meals at the same time each day favored the maintenance of circadian rhythms, including their sleep cycle. Finally, we argue that centenarians' chronic inflammatory status, which we dubbed inflammaging, is peculiar, likely adaptive, and less detrimental than in younger people.
Keywords: calorie restriction; centenarians; circadian rhythms; inflammaging; longevity; nutrition.