The production and consumption of food are responsible for high environmental impacts. While the impacts of the agricultural production of food have been widely studied, less is known about the environmental effects associated with household food preparation by consumers. This study thus had two main goals: to (i) evaluate the influence of consumer practices at home on the environmental impacts of a food product, (ii) to compare the environmental performance of a single type of food prepared using different manufacturing methods (industrial, homemade, and assembled at home). These environmental profiles were also compared to consumers' perceptions and preferences regarding these products. Pizza was chosen as a study model. Sixty-nine participants were recruited to prepare, consume and evaluate six pizzas at home (one ham-and-cheese pizza and one mixed-cheese pizza, prepared using each of the three methods). Participants were asked to complete questionnaires related to their habits, the preparation of the six pizzas, and their perceptions and preferences. Their answers were used to assess the environmental impacts of the pizzas via life cycle assessments (LCA) in SimaPro software using two different functional units (FUs): one pizza and 1 kg of pizza. Our results revealed that consumer practices can vary greatly among consumers which has a significant influence on the environmental impacts of pizza. For both FUs studied, the responsibility of the recipe and of the manufacturing method are preponderant on certain indicators of the environmental profile. Thus the manufacturing method has a decisive influence on the values of the indicators sensitive to electricity consumption. Consumers tend to prefer homemade pizzas and think that they have less impact on the environment, which is not necessarily in line with our results. This study demonstrates the importance of incorporating consumer practices into environmental assessments of food products in order to adequately describe their environmental impacts.