Short bursts of exercise key to feeling full

Participants who did shorter bursts more regularly felt up to 32% fuller between 1pm and 3pm. Image from shutterstock.com

Short bouts of intermittent exercise throughout the day may be better than one vigorous workout in convincing your brain that you are full, according to a new study published in the journal Obesity.

The researchers, from the United States and Murdoch University, set out to find how the appetite-regulating hormone Peptide YY (PYY) fluctuates with intermittent or continuous exercise.

The research team asked the 11 participants to do no exercise on day one, to do a one-hour morning exercise session on day two, and to do 12 five-minute bouts of exercise throughout the third day day.

Blood was drawn every 15 minutes to assess hormones and the subjects were asked to rate their levels of hunger.

The researchers didn’t note any difference in PYY levels when comparing the two forms of exercise.

But on the day the participants did shorter bursts of exercise more regularly, they reported feeling up to 32% fuller between 1pm and 3pm. They also felt fuller between 3pm and 5pm.

Study co-author Tim Fairchild, from Murdoch University’s School of Psychology and Exercise, said a regime of shorter exercise sessions presented a promising alternative for weight maintenance and weight loss.

“Staying physically active at work and home is critical for maintaining low levels of hunger,” he said.

But it’s not just a matter of standing up a few more times at work. “You do actually have to go for a fairly hard five minute walk in order to see any benefits,” Dr Fairchild said.

Associate Professor Tim Crowe, from Deakin University, said the research built on existing evidence that people felt hungry after exercise, which could cause them to eat more.

“But the overall benefit of exercise in helping with weight loss clearly puts it on the right side of the ledger,” said Professor Crowe, who was not involved in the study.

“The key message though is that Australians are nowhere near active enough, and for someone trying to keep their weight in check, then at least 60 minutes a day of physical activity is needed.

"For busy people, this latest research shows that getting your ‘dose’ of exercise in many small five or ten minute chunks all throughout the day could be just as effective as sweating it out at the gym.”

David Dunstan said the next step was to work out how the finding translated to people’s working lives.

The researchers “used a more moderate intensity type approach, that’s where some people may start sweating while they’re exercising,” he said.

“But what happens when you start scaling this down to what is practical and meaningful? You could go and walk the stairs but you’re going to be in your work clothes,” he said.

“So what can people fit into their daily lives without too much disruption to their productivity?”

Professor of Medicine at the University of Melbourne, Joseph Proietto, said the study was well designed but with just 11 participants, the numbers were small.

“It would be useful if someone would undertake a repeat study with more subjects,” he said.

Professor Proietto said that although the researchers examined PYY, there were many other hormones that could also affect appetite, including ghrelin (which stimulates hunger) and insulin.