From Chemistry World, a look at a canine calorie restriction study: "48 puppies from seven litters were raised at a research centre in the US ... Animals were fed either a restricted or normal (control) diet and subjected to regular clinical assessment. Urine samples collected from each dog during these check-ups provided a metabolic record that UK scientists have used to study the biological process of aging and metabolism. The dogs on the restricted diet lived about two years longer than those on the control diet. The last of the dogs died just over two years ago, and [researchers] have now used updated analytical techniques on the old samples to measure life-long biochemical changes. ... levels of gut microbial metabolites, like methylamines, cresols and other aromatic compounds, were different between the two groups of dogs. ... This is significant because altered gut microflora has already been linked to obesity in humans." An interesting fact to add to the list of changes wrought by calorie restriction, and a good comparison to the ongoing primate studies.