Sports scientists from the School of Sports and Exercise Health Sciences (SSEHS) recruited 17 men and 15 women – who were able to swim and cycle at a recreational level – and recorded their food intake after periods of either 60 minutes of swimming, 60 minutes of cycling or resting. Each activity was performed on a separate day, with at least four days rest between each activity.
The study found that the people ate an average of 142kcal more during the swimming trial compared to the control (rest) trial – the equivalent of a 25g packet of crisps or two digestive biscuits.
Lead author Dr James King said: “It is not fully understood why swimming has this appetite-stimulating effect. One possible reason could be because of a link between body temperature loss and food intake – a process known as thermogenesis, where the body uses food to generate heat.
“Another reason could be changes in brain signals and neurotransmitters, the chemicals that carry messages between nerve cells. This is plausible because there are specific regions of the brain linked to appetite and reward. Swimming might stimulate these areas and influence appetite and eating behaviours.
“However, we would need detailed brain imaging studies to confirm whether this is the case.”
A few studies have shown that swimming might not be as effective as other types of land-based exercise modalities for weight-management. But Dr King said that although this latest research supported that idea, more work needed to be done in order to examine more prolonged effects of swimming on appetite and energy balance.
He said: “People should not stop swimming if they are trying to lose or manage their weight. But it would be worth being aware that swimming could make you hungrier and people should resist the temptation to snack or eat more than usual following any swimming exercise.”