One of the pieces of evidence that points to our mitochondria as a prime point of interest for engineered longevity is the correlation between maximum life span and resting metabolic rate (RMR) across species. In that light, this research on calorie restriction and metabolic rate is interesting even though it's an insect study: "Caloric restriction (CR) extends lifespan in most animals, but the mechanisms underlying this phenomenon are the subject of much debate. We investigated the association between longevity and resting metabolic rate (RMR) in Indian stick insects (Carausius morosus) [by] quantifying the response of RMR to diet history ... Over a range of body sizes, [RMR] decreased in response to CR, particularly when food was restricted during juvenile stages. With one exception, RMR of insects in different life-history stages matched current feeding level and was not substantially affected by intake history. Total lifespan was affected by intake, with insects that experienced CR early in development living longer than insects that were fed ad libitum. ... CR and decreased RMR were associated with slower progression through pre-reproductive life-history stages."