Research reveals how a single running session can impact appetite

A single bout of running can lead to an increased reaction for food cues in parts of the brain linked to attention and reward anticipation, revealed a new study that could open up ways of regulating appetite for weight loss.

Previous research showed the quantity of food people eat is influenced by brain processes that are sensitive to changes in the body and the immediate food environment.

Studies have also shown that single bouts of exercise such as running can temporarily suppress appetite.

Scientists have previously suggested that the way we react both physically and psychologically to the sight or smell of food – also known as food cue reactivity – can affect appetite and how much we end up eating.

But the extent and process by which exercise impacts appetite immediately following training has remained elusive.

Researchers, including those from the University of Bristol in the UK, explored whether exercise-induced blood flow changes in the brain can influence how people react to food.

The impact of running on blood flow in the brain and how this influenced brain activity in relation to appetite was assessed in the new study, published in the journal Human Brain Mapping.

As part of the research, 23 men underwent fMRI brain scans before and after 60 minutes of running or rest.

During the scan, the participants 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.

Scientists found that the extent of the exercise session suppressed how hungry participants said they felt.

However, it also increased the reactivity of multiple parts of their brain to food cues.

Researchers also detected changes in blood flow in the brain after exercise, but these changes did not appear to influence the food cue reactivity signals.

This suggests the changes in how participants responded to visual food cues were independent of the overall changes to blood flow in the brain.

“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,” study co-author Alice Thackray said.

The research confirms that the brain plays an important role in the control of appetite and food intake.

“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,” said David Stensel, another author of the study.