Scientists explain why insects don’t get fat

September 27, 2006
Scientists explain why insects don’t get fat
A diamondback moth caterpillar is shown on a Arabidopsis plant. Credit: Dr Spencer Behmer

Insects don’t get fat, and why they don’t may help our understanding of what has been described as the current human obesity epidemic.

The research team from Oxford’s Zoology Department, Texas A&M University, the University of Sydney and the University of Auckland conducted a series of experiments to find out whether caterpillars could adapt to extreme changes in their nutritional environment.

In their study ‘Evolving resistance to obesity in an insect’, published in the Proceedings of the National Academy of Science, they found that diamondback moth caterpillars evolved different physiological mechanisms related to fat metabolism. Which mechanism was used depended on whether the caterpillars were given carbohydrate-rich or carbohydrate-poor food. The researchers believe that caterpillars – and animals in general – can evolve metabolically to adjust to extreme nutritional environments.

The researchers studied the insects over eight generations. In one experiment, they fed caterpillars artificial diets that were rich in protein and low in carbohydrates; at other times the caterpillars received diets low in protein and high in carbohydrates.

In a second experiment, caterpillars were allowed to eat freely one of two plants, an Arabidopsis mutant low in starch or an Arabidopsis mutant high in starch.

When the caterpillars were reared in carbohydrate-rich environments for multiple generations, they developed the ability to eat excess carbohydrate without adding fat to their bodies. On the other hand, those reared in carbohydrate-poor environments showed an ability to store ingested carbohydrates as fat.

Also, after multiple generations on the low-starch plants, female moths preferred to lay their eggs on these same plants. The researchers explain that it is one of the first instances of a moth showing egg-laying behaviour that is tied to a plant’s nutritional chemistry.

The researchers believe moths from low-starch plans might avoid high-starch plants because they might make their offspring obese. Female moths reared on the high-starch plant for multiple generations showed no preference.

The inference made by the researchers is that like insects, humans require carbohydrates and proteins, but that humans are not well adapted to diets containing extremely high levels of carbohydrates – a radically different diet to that of our ancestors. However, they say, lack of exercise might be another factor in why humans convert excess carbohydrate to fat.

Explore further: Fat, thin caterpillars are studied

Related Stories

Fat, thin caterpillars are studied

September 21, 2006

A U.S.-led international team of scientists says there's no obesity epidemic among insects and the researchers believe they now know why.

Moths tell us how organisms use resources

January 6, 2011

( -- Using a one-of-its-kind flight arena, University of Arizona entomologist Goggy Davidowitz and his group study how giant hawk moths use energy resources for two of nature's most costly evolutionary traits: ...

Recommended for you

On soft ground? Tread lightly to stay fast

October 8, 2015

These findings, reported today, Friday 9th October, in the journal Bioinspiration & Biomechanics, offer a new insight into how animals respond to different terrain, and how robots can learn from them.

Ancient genome from Africa sequenced for the first time

October 8, 2015

The first ancient human genome from Africa to be sequenced has revealed that a wave of migration back into Africa from Western Eurasia around 3,000 years ago was up to twice as significant as previously thought, and affected ...

Blue skies, frozen water detected on Pluto

October 8, 2015

Pluto has blue skies and patches of frozen water, according to the latest data out Thursday from NASA's unmanned New Horizons probe, which made a historic flyby of the dwarf planet in July.

New method facilitates research on fuel cell catalysts

October 8, 2015

While the cleaning of car exhausts is among the best known applications of catalytic processes, it is only the tip of the iceberg. Practically the entire chemical industry relies on catalytic reactions. Therefore, catalyst ...


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.