Caloric restriction (CR) with fasting extends lifespan but is difficult to maintain in humans. Here we compared conventional CR (20%; 18% protein, 67% carbohydrate, 15% fat; fed at 3pm) with periods of fasting to an ad libitum-fed low-protein, high-carbohydrate (LPHC) diet diluted 25% with non-digestible fiber (6% protein, 79% carbohydrate, 15% fat) and control fed mice (18% protein, 67% carbohydrate, 15% fat). Due to the cellulose, LPHC mice had an increase in food intake, but an overall decrease in energy intake (~15% CR) compared to controls. Both dietary approaches similarly enhanced longevity and metabolic health (e.g. adiposity, glucose tolerance, fatty liver) relative to controls. Proteomic analysis of liver tissue revealed that CR alone increased proteins associated with energy and mitochondrial pathway. By contrast LPHC diet reduced these pathways but increased abundance of proteins associated with RNA metabolism and spliceosome pathways. These results for LPHC support the “energy-splicing resilience” axis theory of aging. Our results suggest that ad libitum-fed diets can be designed to replicate, and potentially enhance, the geroprotective benefits of CR, albeit via different mechanisms, potentially offering a more sustainable dietary approach to longevity extension.