A black bear

Building supplies

Fat helps give our bodies shape

Fat provides form as well as fuel. If someone is malnourished, their body will turn to other fuels to replace the missing carbohydrates and fats, respiring protein instead. This leads to muscle wasting and results in an emaciated appearance.

Women naturally carry more fat than men do and it is distributed in different ways. The differences start to emerge from puberty, when female bodies start laying down twice as much fat as males in readiness – it’s presumed – for the demands of possible future pregnancies and breastfeeding. Most of the additional fat clings to the thighs, hips and buttocks. In 2009, scientists suggested that the hormone oestrogen could be partly responsible for controlling this additional fat storage.

Excess fat storage is also vital in hibernating and migrating animals. Hibernating bears put on kilograms of fat and double their cholesterol levels before winding down for the winter. Meanwhile, swallows spend time roosting and feeding to accumulate fat before the long journey from Europe to Africa in the autumn. The mass of fat accumulated by different swallow populations across Europe seems to be directly linked to the distance they have to travel – even in young birds that have never made the trip before.

Lead image:

BlueRidgeKitties/Flickr CC BY NC


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About this resource

This resource was first published in ‘Fat’ in December 2015.

Ecology and environment, Physiology
Education levels:
16–19, Continuing professional development