Nutrition fundamentally affects growth and reproduction, and identifying how nutrient intakes are linked to the expression of these life-history traits can advance understanding of the mechanisms underlying life history trade-offs. Males are thought to face trade-offs between the allocation of resources to pre-mating secondary sexual traits for gaining access to females and allocation to post-mating traits such as ejaculate quality that affects their fertility. We used the Geometric Framework for nutrition to examine the effects of macronutrient and micronutrient consumption on lifespan and the expression of pre- and post-mating sexual traits in male field crickets Teleogryllus oceanicus. We found that lifespan was maximized on diets with a low protein to carbohydrate (P:C) ratio, while pre-mating sexual traits (courtship song and cuticular hydrocarbons) were maximized on high P:C ratios. In contrast, sperm viability, a post-mating trait, was lowest on high P:C ratio diets. Higher consumption of micronutrients decreased lifespan and the general abundances of CHCs, but improved the performance of sperm viability and courtship song. We show that different macronutrients are not simply calories to be allocated to different traits, but directly determine the expression of different life history traits and mediate their trade-offs. We also highlight the importance of including micronutrients in the assessment of nutritional effects on the expression of life history traits.