Studies in adult animals as well as in humans have demonstrated beneficial effects of increased intake of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) on lipid metabolism, obesity, and insulin sensitivity. The lipid composition of breast milk, and in particular, the role of n-3 LCPUFA in imprinting of metabolism and its hormonal control need clarification as far as the long-term beneficial effects of breastfeeding on health are concerned. In this respect, animal studies have brought inconclusive results. However, the involvement of adipose tissue-muscle interactions in the short term effects of n-3 LCPUFA during perinatal development, as well as the lasting effects of n-3 LCPUFA intake, are likely to occur and should be further investigated.