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Understanding the brain’s role in obesity
16 August 2013
The world’s growing obesity crisis is rarely out of the headlines, given the increasing burden on the healthcare system and the livelihoods of those affected. More than 1.4 billion adults across the world over the age of 20 are obese according to the World Health Organisation, while during 2011-12, obesity was the cause of 11,736 hospital admissions reported by the NHS. More recently, the British Heart Foundation and Oxford University found that 30 per cent of children and young people in the UK are overweight, paving the way for problems such as diabetes and heart disease.
The abundance of highly calorific foods and aggressive marketing is often blamed. But what makes some people more likely than others to respond to such environmental triggers? And why do they over-eat in spite of the internal signals that control feelings of hunger and satiety? What exactly is the brain’s role in controlling food perception and consumption? And what is the impact of our underlying genetic makeup and hormonal activity?
These are the questions at the heart of a new study that will use neuroimaging techniques to measure the neural, hormonal and behavioural responses to food consumption. Leading the study is Dr Elanor Hinton, who is pooling her expertise in experimental psychology with that of physiologists, childhood obesity clinicians and dieticians in a bid to provide quantifiable evidence of the relationship between obesity and multiple triggers.
“I’m very interested in what motivates people to eat excessively, and the reward value of eating,” says Dr Hinton, who is one of a handful of researchers from the University of Bristol to be granted a fellowship by the Elizabeth Blackwell Institute for Health Research (EBI). “We need to understand which regions of the brain are involved and how they connect before we can do something about it. We are focusing on using state-of-the-art research techniques to understand the processes underlying changes in weight, which we hope to see following the weight management programme. We are interested to see what difference scientific research can make to changing eating behaviour.”
In this study, funded by the Bristol Nutrition Biomedical Research Unit, Dr Hinton will work with childhood obesity consultants and patients from Bristol’s Care of Childhood Obesity Clinic to measure the effects of different weight management programmes. Functional Magnetic Resonance Imaging (3T MRI scanner) at the Clinical Research and Imaging centre (CRIC) will be used to measure blood flow in the regions of the brain associated with satiety and appetite before and after volunteers are given the weight management therapy.
Four groups of up to 15 people will be assessed over a period of six months. One group of overweight teenagers will be given a new tool called the Mandolean, which will show their rate of eating and levels of satiety whilst they are consuming a carefully selected healthy meal. A second group of obese teenagers will be provided with the standard dietary and exercise support, while a third control group of teenagers at a normal weight will take part in one of the brain imaging sessions.
Finally a fourth group of patients with a genetic mutation in the MC4 receptor found in the brain, which has a proven link to obesity, will be assessed for their response to the Mandolean weight management programme.
Measurements of the hormones peptide YY and ghrelin, also known to be involved in appetite, will be taken from the three experimental groups, along with fMRI scans to see the differences in neural activity alongside variations in perception of satiety and eating rate. Crucially, over the six month period, Dr Hinton and her colleagues will be able to track changes in the brain in response to the different weight management programmes.
While previous studies have demonstrated the role of these individual components in obesity, this is the first multidisciplinary study of its kind to apply neuroimaging techniques to track all of the components in tandem. As such, it could provide invaluable advances in the effort to find an effective solution to a condition that to date, has shown no signs of abating.
“Our hope is that the weight management programmes will prove successful and we’ll be able to understand precisely why certain changes are happening,” says Dr Hinton. “I suspect there will be changes in both satiety perception and appetite hormones. Crucially, we hope to understand the processes in the brain that control these changes and whether they can lead to long term change.”
Please contact Aliya Mughal for further information.
“I’m very interested in what motivates people to eat excessively, and the reward value of eating. We need to understand which regions of the brain are involved and how they connect before we can do something about it."