Among ungulates, capital breeding males, especially in highly dimorphic species, support higher reproductive costs than females. Roe deer, a relatively monomorphic species, is defined as an 'income breeder', using a concurrent intake of energy from forage to pay for a reproductive attempt. In a Northern Apennines (Arezzo province, Tuscany, Central Italy) population, we detected sexual dimorphism in adult roe deer according to average body mass (males 11% heavier than females), mandible size (male mandibles are 2% longer than female ones), and tooth measurements (first lower molar 10% higher and mandible cheek teeth row 4% longer in males than in females, providing males with a larger surface for chewing). In our study, body mass and body condition of roe deer males decreased with increasing tooth wear as in females. However, males started losing weight at a lower tooth wear level than females; after losing about 15% (~3.2 kg) of body mass they had greater probability of death than females. For low‐dimorphic species like roe deer, these findings raise new considerations about the role of sexual dimorphism in feed intake efficiency. [ABSTRACT FROM AUTHOR]