Obesogenic dietary factors, such as simple sugars and saturated fatty acids, have been linked to memory impairments and hippocampal dysfunction. Recent evidence suggests that the brain may be particularly vulnerable to the effects of obesogenic diets during early life periods of rapid growth, maturation, and brain development. Investigations utilizing rodent models indicate that early life exposure to "high fat diets" (40-65% kcal derived from fat) or simple sugars (sucrose or high fructose corn syrup) can impair hippocampus-dependent learning and memory processes. In some cases, these deficits occur independent of obesity and metabolic derangement and can persist into adulthood despite dietary intervention. Various neurobiological mechanisms have been identified that may link early life consumption of obesogenic dietary factors with hippocampal dysfunction, including increased neuroinflammation and reduced neurotrophin mediated regulation of neurogenesis and synaptic plasticity. Age, duration of exposure, and dietary composition are key variables contributing to the interaction between early life diet and cognitive dysfunction, however, more research is needed to unravel the precise critical windows of development and causal dietary factors.