Professor Margaret Morris feeds her lab rats the cheapest processed food money can buy. In doing so, she’s showing how a junk food diet changes brain chemistry, affecting behaviour patterns, health and wellbeing.
In research published in Nature in 2010, Morris showed the role of diet is so profound that when rat fathers are fed high fat food to induce obesity and glucose intolerance, their female offspring exhibit similar glucose intolerance and impaired insulin secretion as young adults. This finding offered new insight into the science of epigenetics, which concerns the inheritance of certain physiological traits that aren’t caused by changes in the DNA sequence.
More recently, Morris and her team in UNSW’s Environmental Determinants of Obesity group have demonstrated that a diet of junk food inhibits interest in healthy food and overrides the mechanisms that normally protect against overeating. They’ve also found that just a week of eating junk food impairs memory.
But eating these energy rich snacks like pies, chips and cakes also triggers the brain’s reward system. Morris has provided evidence that eating junk food can, and does, assuage anxiety and stress, including from early childhood trauma. However, these rewards come at a cost to our metabolism.
Understanding the effects of food on the brain is the key to informing new approaches to managing and reversing the major diseases associated with poor diet and obesity, Morris says.
“I care about big diseases and problems and their impact on the brain, and how we can intervene effectively,” she says. “I am trying to systematically unpick problems ranging from the addictive nature of junk food, to how good nutrition can arrest cognitive decline.”
Obesity research was not the starting point for Morris, who began her academic career as a biochemist, later becoming Chair and Head of Pharmacology at UNSW’s School of Medical Sciences.
Her early research in the 1980s looked at the role of neuropeptide Y (NPY) in hypertension. However, when the link between NPY and hypertension proved subtle, she stuck with the peptide and began investigating its role in epilepsy, an interest she maintains. Meanwhile, NPY emerged as a potent appetite stimulant, suggesting another research direction and prompting Morris’ first junk food shopping expedition in 1996.
It was then she discovered that even though her rats’ food intake doubled, junk food didn’t satiate their appetites: “they just wanted to keep eating”, she says.
Morris and her team are now investigating up to 20 brain chemicals across a wide research agenda with the common thread of discovering and understanding the chemical changes in the brain that drive or moderate the many behaviours linked to stress, appetite, food choices and obesity, and their relationship to other major health issues like diabetes and hypertension.
Of particular interest, she says, is the communication between brain, liver, muscle and fat in driving metabolic disease.
“It’s a modern-day struggle with plenty, but it is a struggle we can win,” Morris maintains. “At every level, interventions help. The impacts of junk food are preventable and reversible.”
Morris believes one of the most important interventions is physical exercise. Her studies on animals show that even moderate exercise can lead to significant health improvements.
“This could potentially reduce our dependency on medication and make a huge difference to not only our health but also our national health budget.”