Why bats, rats and cats store different amounts of fat

January 20, 2012

Animals differ in the amount of fat they carry around depending on their species, status and sex. However, the causes of much of this variation have been a mystery. The Bristol study shows that many differences can be understood by considering the strategies animals employ to avoid two causes of death: starvation and being killed by predators.

These causes of death often exert opposite pressures on animals, for example, storing lots of fat helps animals survive periods without food but also slows their running and so makes getting caught by a predator more likely. Animals can be stronger to compensate, but the energetic costs of extra muscle mean that the animal would starve quicker during a .

Led by Dr Andrew Higginson of Bristol's School of , the researchers used mathematical models to explore how much muscle and fat animals should have in their body to give themselves the best chance of survival. They showed that an important consideration was how much carrying fat increases the energetic costs of movement. The models revealed that the size of this cost influenced whether larger animals should have more fat than smaller animals, or vice versa.

Dr Higginson said: "Our results explain differences between different families of mammal. For example, larger bats carry proportionally less fat than small bats but larger carnivores carry more fat than small carnivores. Among rodents, it's the medium-sized species that carry around the most fat! These differences agree with the models predictions if you consider the costs of carrying fat for these three groups. Bats fly and so have high costs of carrying extra weight, whilst spend much of their time resting and so will use less energy than busy scurrying rodents."

The work, published in The , also shows that much of the variation between animals in their amounts of fat and muscle can be explained by differences between the sexes, how much animals have to fight to get food, and the climate in which they live.

The researchers plan to put the theory to the test by looking in more detail at the amounts of fat stored by different animals. If their theory is correct, much of the mystery in how species and sexes differ in their amount of fat will have been solved.

Explore further: High-fat diets plus extra protein make for bad mix

Related Stories

High-fat diets plus extra protein make for bad mix

April 7, 2009

It's basically a given that diets loaded with fat can lead to considerable health problems. But a new study in the April issue of Cell Metabolism, a Cell Press publication, shows that in some cases diets that are high in ...

No need to shrink guts to have a larger brain

November 9, 2011

Brain tissue is a major consumer of energy in the body. If an animal species evolves a larger brain than its ancestors, the increased need for energy can be met by either obtaining additional sources of food or by a trade-off ...

Fat-regenerating 'stem cells' found in mice

October 10, 2008

Researchers have identified stem cells with the capacity to build fat, according to a report in the October 17th issue of the journal Cell, a Cell Press publication. Although they have yet to show that the cells can renew ...

Why nectar-feeding bats need a 'power drink' to fly

August 7, 2007

Nectar-feeding bats burn sugar faster than any other mammal on Earth – and three times faster than even top-class athletes – ecologists have discovered. The findings, published online in the British Ecological Society's ...

'Starving' fat suppresses appetite

February 1, 2010

Peptides that target blood vessels in fat and cause them to go into programmed cell death (termed apoptosis) could become a model for future weight-loss therapies, say University of Cincinnati (UC) researchers.

Recommended for you

Researchers identify genes for 'Help me!' aromas from corn

October 25, 2016

When corn seedlings are nibbled by caterpillars, they defend themselves by releasing scent compounds that attract parasitic wasps whose larvae consume the caterpillar—but not all corn varieties are equally effective at ...

Genome editing: Efficient CRISPR experiments in mouse cells

October 25, 2016

In order to use the CRISPR-Cas9 system to cut genes, researchers must design an RNA sequence that matches the DNA of the target gene. Most genes have hundreds of such sequences, with varying activity and uniqueness in the ...

Structure of key DNA replication protein solved

October 25, 2016

A research team led by scientists at the Icahn School of Medicine at Mount Sinai (ISMMS) has solved the three-dimensional structure of a key protein that helps damaged cellular DNA repair itself. Investigators say that knowing ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.