Background: Obesity is considered to be one of the most important factors reducing the sense of happiness and satisfaction with life, especially among women. This belief already exists in middle childhood, as the preschool period is a crucial point in the development of attitudes towards beauty. Preschoolers can identify physically attractive individuals, and they might already form attributions regarding the looks of adults (especially women), which in turn may constitute a foundation for their future concept of beauty-related happiness. Children’s attitudes towards the body are also strongly influenced by the content of gender stereotypes that prescribe and proscribe what women and men should look like. In our study, we aimed to analyse the relationship between associations of obesity and happiness made by preschool girls and boys (5-year-olds). Methods: A total of 680 families with five-year-old children (329 girls, 351 boys; Mage = 5.7 years) and both parents took part in the study. Children’s associations of different types of body sizes with perceptions of happiness were measured with the Beauty & Health pictorial scale. Results: Our results indicate that obese bodies were seen as unattractive, independent of gender (p < .001). Children associated looks with happiness-the body type identified as the most physically attractive was also seen as a happiest person. Lowest happiness scores were also ascribed to obese body types, but girls assessed men with a normal body type as happier than boys (t = 2.87, p = .004). Conclusions: Female bodies are already perceived along gender stereotypical lines at the age of 5, and are also related to potential predictions concerning women’s happiness. Children assessed female individuals with slim bodies, as well as those with normal weight, as happier than obese females.