Epidemiological associations between an adverse intrauterine environment and the induction of obesity in adult life led to the concept of fetal programming whereby an unfavorable prenatal environment induces adaptations that improve fetal survival or prepare the fetus in expectation of a particular range of postnatal environments. However, these adaptations (predictive adaptive responses) may later prove to be a disadvantage when the pre- and postnatal environments show discrepancies. We investigated the effect of maternal restricted diet on body weight and expression of hypothalamic Ob-Rb of the offspring. Balb C mice were mated after pregnancy and were randomly assigned to control (C) and undernutrition group (UN) groups. Control group was allowed food ad libitum and UN group had a 50% restriction of food intake during gestation. In the present study we assessed changes in hypothalamic Ob-Rb mRNA by RT-PCR in offspring from C and UN groups. The offspring of UN at birth showed 17% less body weight compared with C, but at 90 days the UN had a greater body weight than C (p