Functional guava mousses were prepared with inulin (I) and whey protein concentrate (WPC), in different combinations, with the purpose of partially or totally substituting their milk fat (MF) content, using a simplex-centroid design. In order to verify the adequacy of mousses to comply the standards for the nutrient content and nutrient comparative claims, their composition and energy values were compared with the food legislation adopted currently in Brazil, the European Union (E.U.), and the United States (U.S.), besides the new proposal for the Brazilian standards. Most of the formulations, especially I, WPC, I + WPC, and MF + I + WPC, and except for MF + WPC, were able to fulfil the requisites for receiving the “low” (nutrient content) and “reduced” (comparative) claims for total and saturated fat. Also, products with inulin could achieve the requisites for the “high” claim for dietary fibre. Nonetheless, important differences between the legislations for achieving some claims were noted, especially when the serving portion was used as standard instead of 100 g. This would require some attention by regulatory authorities, once the possibility of manufacturers to reduce or to increase the products’ serving portions up to achieve a claim, misunderstanding the consumer, may exist.