Obesity is a major public health crisis in this country. But with many factors to blame, what can be done about it?
Obesity is increasingly a problem in many countries around the world. Why are our bodies changing? Natalie Johnson/Flickr (CC BY-NC 2.0)
According to the World Health Organisation, worldwide obesity has more than doubled since 1980, and Australia is no exception to this global trend. In fact, obesity is now considered the single biggest threat to our public health and causes more premature deaths than anything else, including smoking.
To put it simply, we are one of the fattest countries in the developed world. With over two-thirds of our adult population either overweight or obese, if current trends continue, research shows that by 2025 that figure will increase to 80%. It is even predicted that, by the time they reach the age of 20, our kids will have a shorter life expectancy than earlier generations, simply because of obesity. We find ourselves with an epidemic on our hands. But what’s behind this crisis?
“In the last hundred years there have been big changes to our environment,” said Professor Michael Cowley, Director of the Monash Obesity & Diabetes Institute (MODI). “Physical activity is no longer a part of our daily lives. In my grandmother’s day, doing the washing meant two days of hard labour. Now, it means pushing a button.” Couple this decrease in physical activity with changes in our food choices and the way we eat, and it’s not hard to see how we’ve overridden our natural regulators to arrive at this state of imbalance.
Chemical signals in the brain have a large part to play in regulating food intake. Allan Ajifo/Flickr (CC BY 2.0)
Basically, we are consuming more energy than our bodies need, and the more we do it, the worse it becomes. This is because the amount we eat is determined by the brain; signals from the gastrointestinal tract combine with social cues in our environment to tell us when we’ve had enough and terminate our food-seeking behaviour. Food-seeking differs from hunger in that the drive to seek food involves decisions: it’s the motivated and goal-directed behaviour that stimulates us to leave the comfort of the couch and walk to the fridge.
Once a certain stage is reached, the food-seeking drive is always switched on. “As people become obese, as they overeat, the brain's ability to detect the hormonal signals that they’ve had enough starts to diminish,” said Professor Cowley. “The brain is then less able to take salience away, to say no to food.” So while the brain of a healthy person receives signals and relays them, that’s not the case when someone’s overweight.
Someone in this state no longer eats for pleasure. Unsurprisingly, this is the same behaviour that you would see in a drug addict. Driven by dopamine, the brain gives certain behaviours a higher salience, or importance, than other behaviours. In the case of chemical addiction, that salience is given to the drug; in a person suffering from obesity, this is given to food intake. “Many drug addicts don’t talk about the pleasure of using their drug,” said Professor Cowley, “but rather the relief…a need that’s met.”
Food becomes less pleasurable as dopamine tolerance increases, even when consuming those considered "guilty pleasures". powerplantop/Flickr (CC BY-NC-ND 2.0)
So despite "eat less, exercise more" being the obvious answer, it’s not that straightforward. As one study by the University of California put it, “you can't assert a cognitive inhibition on a biochemical drive that goes on every minute of every day of every year.” Professor Cowley was adamant that this information takes the moral dilemma away from the argument: “Obesity is not a state of gluttony. Your brain is simply unaware of how much you've eaten and how much weight you've accumulated.”
Nonetheless, obesity is not a state one reaches overnight. We must assume that there is considerable period during which a person consistently operates under an energy imbalance while the brain is still functioning correctly. The Australian Department of Health lists several factors that contribute to obesity, including previous history of weight loss, life stages and events, family, work, social environments, and stress.
And while we grapple with our personal lives, the entire food industry is against us. Companies invest heavily in food design and marketing with the express intention of making us eat more. Even a simple packet of barbecue chips has been crafted towards this, from the colour of the packaging to the way they crunch, and the flavour specifically designed to trigger the food-seeking drive. In addition, these foods then tend to be consumed around the television, alone or on the go, and this compounds the problem by removing the social cues that would otherwise inhibit overeating.
Weight gain is caused by both environmental and neurological influences. Mason Masteka/Flickr (CC BY-SA 2.0)
When questioned about recent fads like the I Quit Sugar program, which decries the addictive nature of sugar, Professor Crowley pointed out that people didn’t hold up supermarkets to get a chocolate fix. “Sugar is one thousand times less addictive than cocaine,” he said. He also hesitated in the face of other popular theories, like timing of calorie intake or sleep patterns (also called social jet lag). “We like the idea that the modern world is a bad thing for us,” Professor Cowley said, “so we can lay the blame on someone else.”
If, then, we’re forced to give up our favourite scapegoats, must we instead bear the burden of personal responsibility? Perhaps not quite as much as it seems. According to Brian Wansink, author of Mindless Eating: Why We Eat More Than We Think and head of the Cornell Food and Brand Lab in the US, research shows that while we make around 250 food-related decisions every day, we can’t really explain those choices. “Most people believe they are master and commander of their food choices,” he says. “I want them to see that they aren’t.”
Clearly it’s time to educate ourselves, but whether the root cause is society, environment, genetics or poor choices, it still remains that we are in desperate need of a solution. Professor Cowley agrees: “Even if we could change Australia today, we would still have over 60% of the population in need of a cure.”
New drugs aimed at treating obesity may curtail food-related illnesses such as type II diabetes. Victor Casale/Flickr (CC BY 2.0)
That’s where the team at MODI comes in. To restore proper brain function, the team is developing new pharmaceutical treatments that will help provide metabolically meaningful weight loss. “We treat obesity as a brain-based disorder and try to understand brain process, and restore its processes as it was when the person was lean,” explained Professor Cowley. One such drug, already approved for use in the US, gives a result of 5–12% weight loss. It also improves glucose levels, meaning that this treatment can lead to remission of diabetes.
As there are currently no good pharmacological therapies available in Australia, there is a need for these new medicines that, he is hopeful, will be available here in the next two years. In the meantime, we can seek to prevent obesity by educating future generations. “For me, this is where the best path is children,” said Professor Cowley, “making physical activity and caring for themselves a part of their daily routine, not just because it’s Friday afternoon sport at school.” We need to get back into the habit of physical activity as a matter of course and restore healthy eating habits — including the family meal around the table — and become more aware of our choices and environments.
We need to eat less and exercise more.
