What insects can teach us about our diet

30 June 2006

Steve Simpson with an Australian locust.
Steve Simpson with an Australian locust.

Mormon crickets stop at nothing to meet their required protein intake: they even eat each other when food is in short supply.

Entomologist Steve Simpson says humans could learn a lot from their example. Professor Simpson, a Federation Fellow in the School of Biological Sciences, doesn't go as far as advocating cannibalism - but he says humans consciously need to increase the amount of protein in their daily diet.

"If humans were able to meet their target protein intake in the same manner as insects, we would not be in the grip of a rampant obesity epidemic," he says.

Professor Simpson's ground-breaking research into the eating patterns of insects has led him directly into the field of human nutrition, where his work may help people cut their ballooning appetites and their waistlines.

Using a geometric framework, he and colleague David Raubenheimer from the University of Auckland conducted multiple experiments into the eating habits of locusts, rats and other animals. They showed that "their appetites are dominated by their intake of protein. They will eat - or do, as in the case of crickets - whatever it takes to hit their required target protein intake".

His studies showed that if the insects were fed on diets low in protein and high in carbohydrate, they would overfeed until they reached their target protein intake. However, when fed on diets high in protein and low in carbohydrate, they ate the same amount of protein - and did not need to eat more to compensate for the lack of carbohydrates.

Recognising the implications for the role of protein in animal diets, he decided on an unusual experiment to investigate its impact on humans.

"We incarcerated ten individuals in a hotel room in Switzerland for six days. Over the first two days we offered them a buffet menu and measured everything they ate. Over the next two days, we restricted one group to high-protein foods, like meat and chicken, and the other to food high in carbohydrates and fat, like croissants and breads."

The results were telling. "The first group did not overeat and consumed exactly the same amount of protein as they had done on the previous days. However, the second group, went way off the mark and just kept on eating until eventually, through their over consumption of carbohydrate-rich foods - which, often contain relatively low amounts of protein - they managed to fill their protein intake."

The experiments signalled the role of protein as the body's main appetite regulator and suppressor and lent support to his feeling that many of the problems we see today are directly caused by a shift in our diets towards a far greater amount of processed foods, which contain a low proportion of proteins and large amounts of cheap ingredients like corn starch and refined sugars.

Even rats, which have an innate ability to converge upon and maintain their optimum nutrient intake levels, tend to overeat when placed on high carbohydrate diets, said Professor Simpson.

Adding leverage to his arguments are figures from America showing that in the 1960s the average person's energy intake consisted of 14 per cent protein. By 2000, this had dropped to 12.5 per cent - a small decline. However, in order to compensate for this apparently trivial fall in protein, intake of fats and carbohydrate rose by 14 per cent.

"This clearly demonstrates that a slight shift in the diet towards a lower proportion of protein can have catastrophic effects," he said.

"Atkins may have recognised, to a certain point, the benefits of protein in weight control - ordering his followers to cut out all carbohydrates from the diet and restricting their diets to fats and protein only. However, to remove all carbohydrate from the diet is risky," he said.

"Our model shows that it's simply the percentage of protein in the diet that matters and you only need a moderate reduction of carbohydrates or fats, because your protein appetite control system will naturally inhibit the over-consumption of the other two nutrient groups."

Contact: Mandy Sacher

Phone: 02 9351 3168