We investigated the effect of a chronic palatable diet rich in simple sugars on memory of different degrees of emotionality in male adult rats, and on hippocampal plasticity markers in different stages of development. On postnatal day (PND) 21, 45 male Wistar rats were divided in two groups, according to their diet: (1‐Control) receiving standard lab chow or (2‐Palatable Diet) receiving both standard chow plus palatable diet ad libitum. At PND 60, behavioral tests were performed to investigate memory in distinct tasks. Hippocampal plasticity markers were investigated at PND 28 in half of the animals, and after the behavioral tests. Palatable diet consumption induced an impairment in memory, aversive or not, and increased Na+, K+‐ATPase activity, both at PND 28, and in the adulthood. Synaptophysin, brain‐derived neurotrophic factor (BDNF), and protein kinase B (AKT), and phosphorylated AKT were reduced in the hippocampus at PND 28. However, at PND 75, this diet consumption led to increased hippocampal levels of synaptophysin, spinophilin/neurabin‐II, and decreased BDNF and neuronal nitric oxide synthase. These results showed a strongly association of simple sugars‐rich diet consumption during the development with memory impairments. Plasticity markers are changed, with results that depend on the stage of development evaluated.