In a recent article in Cell Metabolism, Piper, Partridge, Raubenheimer and Simpson report that Dietary restriction (DR) and mutations in nutrient signaling pathways can extend healthy life span in diverse organisms. Studying the interaction between these interventions should reveal mechanisms of aging, but has yielded some apparently contradictory results. A multidimensional representation of nutrition, called the geometric framework, can better describe the responses of life span and other traits, including metabolism, and can reconcile these apparent contradictions. They compare the response of Life Span to Nutrient Balance in Different Genotypes using insects like the fruitfly Drosophila melanogaster, the queensland fruitfly, Bactrocera tryoni and the field cricket Teleogryllus commodus. They provide examples showing that it is more informative to analyze DR in terms of dietary balance and that dietary optimization for life span is critical for studies examining the biology of again and other traits.