Fat supplies found in a woman's thighs and buttocks are needed to develop babies' brains, scientists have claimed.
The cells were found to contribute directly to brain development during breastfeeding, with a woman's behind acting as a reserve for vital nutrients.
The claims were made by researchers from the University of Pittsburgh, who added that women with large quantities of such fats in target areas were shown to produce more intelligent children.
"You need lots of fat to make a nervous system and the fats in these areas are also enriched in DHA (docosahexaenoic acid) which is a particularly important component in the human brain.
"It looks as if women have evolved to accumulate these fats and hold on to them - until a baby arrives."
While the stubborn cells are constantly there, they are mobilised during pregnancy to allow a baby's brain to soak up their enriching properties, he added.
The findings are published in Dr Lassek's recent book, Why Women Need Fat, and go a long way in explaining the fundamental differences between male and female forms, he said.
In the past men have been proven to lose weight at a faster rate than women, with the psychological and physical differences contributing to huge discrepancies.
"The male hormone testosterone and the female hormone oestrogen shape our fat distribution at puberty and continue to during our lifetime," says Dr Philip McTernan, associate professor in diabetes and metabolism at the University of Warwick.
"Women tend towards a pear shape, with fat around the hips, while men store fat more centrally around their belly from where excess weight is more easily lost.
"On top of that, oestrogen encourages fat storage, while men have more muscle mass so higher metabolisms which burn calories quicker."
Women also have a higher proportion of fat compared to men - around 20-30 per cent against just 9-18 per cent - which their body will strive to preserve.
- Daily Mail