Energy balance and protein gain contribute significantly to an animal's survival. Although data are available for certain species in captive settings, there is little information on these factors for primates living in their natural environments. In this preliminary study, we combined detailed behavioral, phonological, and chemical data for a well habituated chimpanzee community from the Taï National Park, Côte d'Ivoire, with estimates of energy gain and expenditure from captive chimpanzees and humans to investigate how energy balance and protein gain across age-sex categories are affected by seasonal variations in food availability and how chimpanzees correspondingly alter their feeding and daily journey length (DJL). Comparisons between fruiting seasons characterized by varying quantities and qualities of available food revealed that food quality had the largest effect on individual energy balance and protein gain. Within given fruit seasons, energy balance and protein gain did not vary among age-sex categories. However, there was, variation across seasons among adult males and young of both sexes, but not among adult females. Our study revealed important effects of periods of food scarcity to which chimpanzees reacted by reducing their DJL and increasing their feeding time.