Eat Like the Animals
When it comes to food, nature knows best
Think of a locust. Actually, it’s quite hard to think of a single locust. They travel in plague proportions, consuming crops and ravaging regions. You might not imagine these greedy little insects to be fussy eaters, instinctively adjusting what they devour in pursuit of the perfect balanced diet. Time to think again.
It’s 1991 and two scientists sit together at a computer in a small office at Oxford University. The men are exhausted. They’ve just completed a huge experiment in dietary science. Long days in a cramped, overheated lab, feeding precise quantities of 25 carefully prepared foodstuffs (differing proportions of carbs and protein) to 200 hungry young locusts. Every day they’ve meticulously measured how much each insect has consumed. Now that the locusts have reached maturity, the experiment is over and the scientists stare at the results. What they’ve discovered will go on to have profound implications for our own, human, relationship with food, especially for those looking to fuel healthy and active lifestyles.
David Raubenheimer and Stephen Simpson are now professors at the University of Sydney. They’ve condensed 30 years of dietary research into a ground-breaking new book, Eat Like the Animals. “Little did we know at the time,” says Raubenheimer, “but our locust experiment would set us on a journey that would cover the animal kingdom and across the world, and lead to a radical new theory to tackle the human obesity epidemic.”
COMPETING APPETITES
The Oxford findings suggested that, if exposed to a variety of nutrients, the insects would automatically eat the precise amounts of carbohydrates and protein they needed to develop healthily and reach adulthood. This was an instinctive process: the locusts’ brains using their taste sensors to direct them to eat the required foods.
The story ended less happily for those locusts given imbalanced foods containing too little protein or too few carbs. Simpson and Raubenheimer had discovered that the locust’s famously voracious appetite was actually two appetites: one governing protein consumption and the other carbohydrate. Under ideal conditions the appetites worked in harmony, guiding the insect towards a perfectly balanced diet. But if one nutrient was restricted, the two appetites would compete. In the case of the maturing locusts, the protein appetite came out on top and drove their eating habits. Those insects with a protein-rich diet would eat the
“WHEN PROTEIN WAS SCARCE, THE ANIMALS WOULD OVERCONSUME THEIR CARB-RICH/ LOW-PROTEIN FOODS UNTIL THEIR DAILY PROTEIN QUOTA HAD BEEN REACHED”
right amount of protein and mature normally, but would choose to eat fewer carbs and ultimately lacked energy reserves.
The locusts whose supplied food was carb-rich but low in protein were even more interesting. They had to consume much greater quantities in order to get the protein their developing bodies required, meaning they ingested far more carbohydrates than was good for them. The result was almost comical, says Simpson, with the insects resembling chubby knights squeezed into suits of armour. “It’s hard to tell from the outside that a locust is obese; their hard exoskeleton keeps it all in. But they are chubby on the inside, their vital organs compressed by fat.”
Encouraged by their findings, Raubenheimer and Simpson carried out similar research into other animal species. The results were the same. Given optimum conditions, these creatures would automatically select carbs and protein in perfect proportions. When protein was scarce, the animals would over-consume their carb-rich/ low-protein foods until their daily protein quota had been reached – even if it meant packing on the timber to do so. Perhaps inevitably, the scientists began to wonder if humans were any different.
THE HUMAN LOCUST
We move ahead to 2001 and an isolated chalet in the Swiss Alps, where ten test subjects are experiencing the human equivalent of the locust experiment.
At first, the volunteers are allowed to choose their own menus from a mixed buffet of carefully weighed and measured foods. Two days later they’re split into groups. One group is offered a limitless, protein-rich diet, with little carbs and fat. The others get all-they-can-eat pasta, bread, even cake, but the protein content is limited. Everything both groups consume is meticulously noted.
Simpson and Raubenheimer are fascinated by the results, which are later backed up by larger studies. When allowed to choose their own foods from unlimited quantities of protein and carbs, the individuals all selected, on average, 18 per cent protein in their daily food intake – well within the 15 to 20 per cent range considered normal for human nutrition. Once on the restricted diets, both groups consumed protein in similar quantities to the first part of the experiment, but now their calorie intakes varied dramatically. The protein eaters ended up consuming 38 per cent fewer calories overall, while the carb consumers increased their calorie intake by 35 per cent. “We called this ‘protein leverage’,” says Simpson, “the power of protein to drive excess calorie intake when protein becomes diluted by carbs and fats in the diet.”
PROTEIN TO THE RESCUE?
It was a fascinating finding. A highprotein human diet can significantly reduce our desire to consume carbs with a corresponding drop in calorie intake. Had Simpson and Raubenheimer found the magic key to healthy human nutrition? Wasn’t this what athletes and gym-goers have been saying for years: you can’t get too much protein? Now the science seemed to be suggesting that by increasing the proportion of protein in the diet, we would lose the urge to consume carb calories.
The pair knew they had to look at this in more detail and turned again to the animal kingdom. This time, they conducted lengthy experiments involving fruit flies and mice, hoping to plot the effects of high-protein diets over an entire lifetime. The results were conclusive, and crossed over into human biology: too much protein has a dramatic life-shortening effect. “Our experiments showed that a diet containing too much protein, especially when coupled to low carbs, promotes ageing by driving ancient biological processes that are shared by all animals,” says Simpson.
While it’s too dramatic to say that protein kills, it’s obviously not a nutritional silver bullet either. And there’s clearly a case for moderating protein intake if we want to live to
a ripe old age. e answer, says Raubenheimer, is to make sure we eat the right amount: “It’s wrong to think that more of any good thing should be better than precisely the right amount. ere are plenty of other bene cial substances that are toxic at too high a level. A balanced diet includes each nutrient consumed at its target level.”
PEAK PROTEIN
So protein, eaten in the right proportions, will control the appetite and prevent over-consumption of carbohydrates. Too little protein and we put on unhealthy weight. Too much and we risk under-fuelling our bodies and, worse, shortening our lifespans. e question is, how do we know we’re getting the right amount?
Enter the twin concepts of ‘protein turnover’ and the ‘protein target’. We need to consume protein daily, because every day we lose some.
is is protein turnover. How much a body breaks down depends on age, size and activity level. To maintain or increase muscle mass, we need a protein target to match our turnover.
“Achieving the right diet for your age and lifestyle is a balancing act,” says Simpson. “Start simple and think of trying to hit a daily target intake for both protein and energy (calories). Your protein target will increase when you’re building and repairing muscle. Your energy needs will go up the more you exercise.”
Simpson and Raubenheimer provide a formula for estimating daily protein targets (see panel). ey warn against overloading protein intake, even after a huge gym session. A holistic approach to post-workout recovery, incorporating balanced nutrition and rest, will work better than washing down steak and eggs with litres of protein shakes. “ere’s an optimal dose of protein needed to activate muscle synthesis,” says Simpson, “which is 25-30g in a meal. More than that has no added bene t.”
He recommends leaving three hours between meals, and fasting properly overnight to assist the sleeping body as it repairs the damage to tired muscles. Healthy carbs in the diet will also help with this process.
“Above all,” he says, “listen to your appetites. If you’re craving savoury avoured foods, this means your body is telling you to eat more protein. If you don’t feel like eating protein-rich, savoury avoured foods, then don’t. Your body knows when you’ve got enough.”
ULTRA-PROCESSED ENEMY
In addition to those with active lifestyles, the two scientist’s research has real implications for people wishing to lose weight and improve their diets. In their protein leverage hypothesis, they believe they’ve uncovered the cause of the global obesity epidemic. Until relatively recently, average protein intake for populations across the world was stable at around 15 per cent of daily calories consumed. But in America, between 1961 and 2000, it fell to 12.5 per cent. Suddenly the population of a whole country was unwittingly over-consuming carbs as their bodies encouraged them to eat more in search of that missing protein. is phenomenon coincided with the rapid growth of mass-industrialised food production in the States – a process which subsequently spread around the globe and is now a ecting even the planet’s most isolated communities.
e human animal now nds itself in a confusing and increasingly arti cial food environment. Protein leverage, which evolved over thousands of years to steer us towards a balanced diet, is now working against us. Simpson and Raubenheimer lay the blame at what they call ‘ultraprocessed’ foods.
“ese are industrial products,” says Raubenheimer, “mass produced in machines from re ned ingredients, many of which have nothing to do with nutrition. is food is designed to provide pleasure rather than sustenance. It is to diet what sex toys are to romance.”
BACK TO NATURE
Raubenheimer and Simpson’s research o ers an escape route from the modern food environment that has been corrupted by big business and our convenience-craving lifestyles.
“We don’t need another diet book,” says Raubenheimer. “No animal in the history of life on earth has ever needed one of those. What we’ve done is examine how other species choose a balanced diet using only their biology and explained how you can do the same. Simply expose your appetites to a healthy food environment, and they will take care of the rest.”
“LISTEN TO YOUR APpETITES… YOUR BODY KNOWS WHEN YOU’VE HAD ENOUGH”
“THE HUMAN ANIMAL NOW FINDS ITSELF IN AN INCREASINGLY ARTIFICIAL FOOD ENVIRONMENT”