College of Healthcare Sciences
3 December 2021
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It ain’t easy being lean
Do you find it difficult to develop healthy eating habits? Is regular exercise hard for you to maintain? Many people face these struggles, but discoveries in health and psychological research may hold the answer to your fitness breakthrough. A PhD student at the University of Western Australia (UWA), under the supervision of JCU Professor James Dimmock, sought to tackle this problem by answering a key question: can different exercises help us choose healthier foods?
James Dimmock is a Professor of Health Psychology at JCU. James is co-chair of the ‘Psychology of Active, Healthy Living’ Group, a group that is partnered with UWA and is focused on applied health psychology. Another participant in this group is Natalya Beer, a PhD student at UWA. Her Honours and PhD theses sought to discover which factors of a workout influenced a person’s eating choices, as well as which types of exercise encouraged healthier diets.
The main focus of this research was to find the best methods of weight loss. “There’s a lot of literature showing that even though exercise good for us for many reasons, exercise alone doesn’t really do a lot for weight loss,” James says.
The journey to find where exercise fits into weight loss began with Natalya’s Honours project. “Our team investigated how the specific nature of an exercise session, both in terms of the format and psychological experiences, influences the types and amounts of food we consume in the hours that follow,” Natalya explains.
The moment of choice
To investigate how specific types of exercise and different workout experiences can influence diet choices, Natalya and the research team had people come into a gym for a research-related workout session.
Some people were able to choose many different conditions of the workout, from the type of exercise to the music. Others who participated had to follow the exact parameters that had been chosen by other participants. After the workouts, the researchers gave the participants a breakfast buffet as a thank-you for contributing to their study, the focus of which the participants were unaware of.
Interestingly, participants’ choices of food were different depending on whether or not they experienced choice in their exercise session. Participants who had choice over their workout made healthy food choices, while participants who had no choice in their workout made poorer food choices.
This project helped Natalya to determine that exercise conditions affected nutrition outcomes. Natalya’s PhD project then sought to determine how specific exercises could also influence those outcomes. “We wanted to build on research that showed that High-Intensity Interval Training (HIIT) seemed to produce better food responses afterwards,” James says.
In order to test that theory, they would need to do another workout session.
Sprinting towards a discovery
The next research session was designed to compare food responses in relation to: (a) the physical requirements of a workout session (sprint interval training v moderate-intensity training), (b) psychological experiences in a workout session (friendly and supportive v no-support), and (c) possible interactions between those factors.
Participants in this study were invited to undertake either sprint-interval training (short sprints separated by low-intensity breaks) or moderate-intensity continuous training across two sessions, with each session totalling the same amount of work. Across both types of exercise format, participants either experienced a friendly, supportive social environment or had a no-support environment.
The results of this study showed that sprint-interval training was perceived as more enjoyable, required more exertion, and led to a higher heart rate and blood lactate in comparison to moderate-intensity training.
In relation to food choices, this study also showed that a key hormone related to hunger — known as ghrelin — was lower following the sprint interval training than in the moderate-intensity training. Participants consumed less energy from food after sprint interval training in a positive social environment.
Interestingly, the researchers also found an interaction between training format and psychological experiences for energy intake. Participants in the support group consumed less energy from foods following sprint interval training than from moderate intensity exercise.
Applying research results to workout results
The results of the second research session confirmed Natalya’s theory.
“We are very excited about this research,” Natalya says. “Our findings show that the way you exercise can affect the likelihood of consuming tasty but unhealthy foods and drinks in the hours that follow. This can help to maximize the benefits of exercise, so that if people do go to the effort of exercising, they can achieve the full benefits to their health and wellbeing.”
So, what’s the next step for this fast-paced research?
To take this research to the next level, James, Natalya and their team are investigating how different conditions influence people’s food consumption, food choices, and body composition after 12 weeks of training. “We’ve all heard that small changes can make a big difference,” Natalya says. “So, if people do or don’t indulge two or three times a week, it could add up to significant health in the long term — and it is these long-term effects that we are currently investigating.”
In applying the findings of this research, it is important not to forget the important role of the conditions of an exercise. “To me, this project is interesting because it demonstrates that social climate can change a person’s eating choices,” James says.
If you have a weight-loss goal, try combining sprint interval exercise with a positive social environment. Whether it’s finding a trainer who supports you, exercising with a friend, or joining a fitness group, make the most out of your workout so that you can make healthy nutrition choices, achieve your goals, and enjoy the process.
Professor James Dimmock
James is a Professor of health psychology at James Cook University, and an Adjunct Professor at The University of Western Australia. He is a co-director of the award-winning Psychology of Active, Healthy Living (PAHL) group. PAHL is a cross-institutional health psychology group involving James Cook University and the University of Western Australia. In his role in PAHL, James works with researchers, students, industry, government, the non-profit sector, and the media to improve health outcomes in various populations.
PAHL's (and James's) mission is to harness the 'power of people' to promote mental and physical health in people from all walks of life. The group has developed, delivered, and evaluated numerous community programs that have helped thousands of Australians to live happier and healthier lives. Among other things, PAHL has helped people to lose weight, improve their mental health, make better dietary choices, be more physically active, and feel less stressed at work and home.