Protein and carbohydrate availability can profoundly influence development speed, size, and reproduction. To date, most researchers investigating nutritional effects have only examined one nutrient at a time. Furthermore, when researchers have examined multiple nutrients, their studies have focused on adults, ignoring juveniles. I quantified how dietary nutrient balance (protein:carbohydrate) during development and adulthood impacted fitness conferring traits using male Jamaican field crickets (Gryllus assimilis). I also examined juvenile and adult dietary nutrient preferences. My findings revealed males grow larger and faster, and begin signalling earlier when reared on high protein diets, but switching diets in adulthood did not impact signalling. Additionally, when given a choice, males consumed greater amounts of carbohydrates relative to proteins. Given larger males signal more often and produce more attractive signals, and females preferentially mate with larger males, the ability to locate and consume high protein nutrients during development profoundly impacts male fitness.