Social pressures conflict with biological evolution when it comes to food
Imagine a polar bear in the desert.
It lumbers around doing exactly what it does in the arctic, conserving heat, even though it now lives in a dry arid climate.
It’s not hard to figure out the polar bear probably isn’t very happy or healthy.
Well, Dr. David Katz believes humans in affluent societies are suffering the same fate as a polar bear in the Sahara.
An associate clinical professor of public health and medicine at Yale University School of Medicine, Katz believes humans, calorie conservers, are facing an epidemic of obesity as we continue to hoard calories even though food is now plentiful.
"If you are a polar bear and you have little heat, the heat you conserve is good," said Katz.
"But if you have a lot of heat, the heat you conserve is a problem.
"We are designed to conserve calories in exactly the same way. If you hang on to calories in a world where there aren’t too many it is a good thing. But if you hang on to them in a world where they are falling from the trees… it’s not so good and that is exactly the problem."
Katz has just authored a new book, The Way to Eat, due out in December, which he hopes will help people chart a course through the obstacles we now face as we learn to live in an environment our species was not designed for.
In the US eight out of 10 people are overweight. While Canada isn’t quite as bad there are serious questions being raised about how to address the issue.
Statistics Canada estimates that about 46 per cent of Canadians are overweight and about 15 per cent are obese. And 80 per cent of Canadians don’t exercise enough to be healthy.
The combination of fatty foods and inactivity is said to add billions to the health care tab annually and kill an estimated 21,000 Canadians prematurely each year.
It’s not like most people want to be fat and unfit. We spend about $60 million a year in North America fighting fat.
But with only about a quarter of people who lose weight able to maintain the weight loss it is becoming apparent that there is more at work here than just will power.
Everybody knows being overweight is bad for you, so if it was just a question of knowing the facts and "putting your mind" to dropping a few pounds the media wouldn’t report on the issue incessantly.
Clearly there are other forces at work, both social and biological, which make it difficult to lose weight. Experts have long theorized that every body carries around a biological formula for body weight, which totally conflicts with the way we live and view ourselves today.
Then there are the 250 genes and genetic elements associated with body weight which according to a recent issue of Obesity Research magazine, regulate everything from metabolism to the hypothalamus, which regulates appetite.
Now we are learning that we have to battle our very evolution.
For example, according to Katz, we are born with an instinctive fear of hunger.
"Throughout most of the ages of humanity there hasn’t been enough food, or barely enough, so going for a long time without eating is a scary thing for Homo Sapiens," he said.
"Yet in the modern world where people have constant access to abundant food one of the strategies they tend to use to try and control weight is to try and avoid food altogether.
"Well it doesn’t work. It never works because what it does is essentially activate this primal fear of hunger.
"Extensive anthropological literature shows that many omnivorous species, hunter-gatherer tribes throughout the world and in all probability our ancestors, were binge eaters and it was normal for this reason.
"When they had food they ate like hell not knowing if they were going to eat again any time soon.
"So basically that is what we are activating if we go for a long time without eating."
Humans also tire of a single food taste and will stop eating it when the body has had enough.
But given a variety of choices people will just keep going. That’s why a buffet is a dangerous thing. People will sit and graze for hours even when they are full to bursting.
The reason behind this, said Katz, reaches back to our cave man days. Our body knew that it could not survive on meat alone so it was programmed to put down that joint after a while and go get some berries or roots or fish.
You can imagine how this desire is playing havoc with our eating habits today. Every food we pick up is crammed with flavours and we just keep eating. Unfortunately many foods are also full of preservatives, salts and sugars which we really don’t need, or at least not in the amounts we eat today.
And, of course, cavemen and women loved fat. They had to have it to survive. In fact we just have to have it.
Researchers have discovered that we carry specific receptors that urge us to eat fat and to love it, love it, love it. In fact, the more we get the more we want.
"All of this makes sense in an evolutionary context," said Katz.
"The notion that if it tastes good it’s bad for you in historical terms is completely wrong.
"The things we like are the very things we needed to like to keep us going. But we figured out what we like; now we mass-produce it, and now we have a problem."
Add that to an individual’s specific biological and social pressures and no wonder people gain weight.
Many people have slower sympathetic nervous systems so their heart rate and metabolism are slow. A starvation diet will do nothing to help them because their bodies are made to survive without food, or at least survive better than most people’s bodies.
And peoples’ craving are also influenced by their bodies. It does not take the same amount of will power for one person to say no to cake as it might take another person.
But one thing is for sure: No matter what method people use to try and lose weight, keeping it off will only work if moderate exercise is part of the plan.
Katz firmly believes the sensible route to keeping weight off is to use common sense to eat. But to be successful you must understand the obstacles in the way and find solutions for them.
"Weight control should never be the exclusive goal of eating well," said Katz. "…What I am arguing for is not a diet you go on, not a form of self-sacrifice, but a path to preserve the pleasure of eating but master the modern day nutritional environment."
