Summary: Exercise appears to amplify the brain’s response to food cues, a new study reports.
Researchers observed that running increased the reactivity of certain brain regions linked to attention, anticipation of reward, and memory. These changes occurred independently of overall alterations in brain blood flow.
This fresh insight could further our understanding of the complex relationship between exercise, appetite, and food intake.
Running increased the brain’s reactivity to food cues, independent of changes in brain blood flow.
Participants reported feeling less hungry after exercising, despite their brain’s heightened food cue reactivity.
This research could expand our understanding of how exercise influences appetite and food intake, offering potential strategies for managing unhealthy weight gain.
Source: Loughborough University
A single bout of exercise increased reactivity to food cues in parts of the brain associated with attention, anticipation of reward and episodic memory, according to research published in Human Brain Mapping.
Researchers from the UK’s Loughborough University, University of Bristol, University of Nottingham and the University of Leicester, and Waseda University in Japan investigated the impact of running on blood flow in the brain and how this influenced brain activity in relation to appetite.
They found that changes in how participants responded to visual food cues happened independently of the overall changes to blood flow in the brain.
How much we eat is influenced by systems in the brain that are sensitive to changes in our body and the food environment we are in.
Previous studies have shown that single bouts of exercise such as running can temporarily suppress appetite. However, we don’t fully understand the extent to which exercise impacts how likely we are to eat.
Food cue reactivity is the way our body responds to food. It’s the way we react (both physically and psychologically) to the sight or smell of food, for example. Food cue reactivity can have an impact on our appetite and how much we end up eating.
The study team wanted to explore whether exercise-induced blood flow changes in the brain can influence how people react to food. These changes can be captured using functional magnetic resonance imaging (fMRI). fMRI scans help us evaluate what is happening in the brain by detecting small changes in blood flow.
For this study, twenty-three men underwent fMRI scans before and after 60 minutes of running or rest. During the scan, they were asked to look at three types of images ranging from low-energy dense foods such as fruits and vegetables to high-energy dense foods such as chocolate, as well as non-food items such as furniture.
Researchers found that the bout of exercise suppressed how hungry participants said they felt but it increased the reactivity of multiple parts of their brain to food cues. Using a different type of fMRI, the study team also detected changes in blood flow in the brain after exercise, although these changes did not appear to influence the food cue reactivity signals.
Dr Alice Thackray, a Senior Research Associate in Exercise Metabolism from Loughborough’s School of Sport, Exercise and Health Sciences (SSEHS) was the lead author for the study.
She said: “Our findings confirm individuals feel less hungry during and immediately after an exercise session and provide some insights into the short-term influence of exercise on brain appetite responses.
“Although additional research is needed to determine the implications of these findings, we know the brain plays an important role in the control of appetite and food intake.
“This study is part of an exciting collaboration that we plan to develop further as we continue to explore how exercise and appetite interact, including the influence on central (brain) responses.”
David Stensel, Professor of Exercise Metabolism in SSEHS, added: “The role of exercise in modifying appetite and assisting with weight control remains a hotly debated topic. This research demonstrates that how our brains respond to food cues can be altered by exercise.
“The study provides a springboard for further work to characterise appetite responses to exercise more precisely and comprehensively. This, in turn, will give us a better understanding of the role of exercise in preventing and managing unhealthy weight gain.”
Dr Elanor Hinton from the university of Bristol, said: “This research began as a small pilot collaboration between two NIHR BRCs in Loughborough and Bristol. We are delighted that our initial plans have grown to produce this publication in Human Brain Mapping, in which we have shared our respective expertise.
“A further publication is now pending from this fruitful collaboration, demonstrating the value of collaboration across our research groups.”
About this exercise and neuroscience research news
Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging
Acute exercise suppresses appetite and alters food-cue reactivity, but the extent exercise-induced changes in cerebral blood flow (CBF) influences the blood-oxygen-level-dependent (BOLD) signal during appetite-related paradigms is not known.
This study examined the impact of acute running on visual food-cue reactivity and explored whether such responses are influenced by CBF variability. In a randomised crossover design, 23 men (mean ± SD: 24 ± 4 years, 22.9 ± 2.1 kg/m2) completed fMRI scans before and after 60 min of running (68% ± 3% peak oxygen uptake) or rest (control).
Five-minute pseudo-continuous arterial spin labelling fMRI scans were conducted for CBF assessment before and at four consecutive repeat acquisitions after exercise/rest. BOLD-fMRI was acquired during a food-cue reactivity task before and 28 min after exercise/rest.
Food-cue reactivity analysis was performed with and without CBF adjustment. Subjective appetite ratings were assessed before, during and after exercise/rest.
Exercise CBF was higher in grey matter, the posterior insula and in the region of the amygdala/hippocampus, and lower in the medial orbitofrontal cortex and dorsal striatum than control (main effect trial p ≤ .018). No time-by-trial interactions for CBF were identified (p ≥ .087).
Exercise induced moderate-to-large reductions in subjective appetite ratings (Cohen’s d = 0.53–0.84; p ≤ .024) and increased food-cue reactivity in the paracingulate gyrus, hippocampus, precuneous cortex, frontal pole and posterior cingulate gyrus. Accounting for CBF variability did not markedly alter detection of exercise-induced BOLD signal changes.
Acute running evoked overall changes in CBF that were not time dependent and increased food-cue reactivity in regions implicated in attention, anticipation of reward, and episodic memory independent of CBF.