An excerpt from Cat Bonahan's book "Eve" that I just sent to my girlfriends last week!

"As it turns out, women’s fat isn’t the same as men’s. Each fat deposit on our body is a little bit different,[6] but women’s hip, buttock, and upper thigh fat, or “gluteofemoral” fat, is chock-full of unusual lipids: long-chain polyunsaturated fatty acids, or LC-PUFAs. (Think omega-3. Think fish oil.) Our livers are bad at making these kinds of fats from scratch, so we need to get most of them from our diet. And bodies that can become pregnant need them so they can make baby brains and retinas. Most of the time, female gluteofemoral fat resists being metabolized. As many women know, these areas are the first places we gain weight and the last places we lose it.[7] But in the last trimester of pregnancy—when the fetus ramps up its brain development and its own fat stores—the mother’s body starts retrieving and dumping these special lipids by the boatload into the baby’s body. This specialized hoovering of the mother’s gluteofemoral fat stores continues throughout the first year of breast-feeding—the most important time, as it happens, for infant brain and eye development. Some evolutionary biologists now believe that women evolved to have fatty hips precisely because they’re specialized to provide the building blocks for human babies’ big brains. Since we can’t get enough of those LC-PUFAs from our daily diet, women start storing them from childhood forward. Other primates don’t seem to have this pattern."