Walking for 15 minutes may help overweight people at least temporarily reduce cravings for high-calorie, sugary snacks, a small study suggests.
"This study showed that brisk walking can be used as a strategy to reduce momentary food craving," said Adrian Meule, a psychologist at Ruhr University Bochum in Germany who wasn't involved in the research.
Exercise may provide some cognitive stimulation that interferes with thoughts about the craved food, and the discipline to regularly take walks to circumvent cravings might also improve the ability to follow through with healthy food choices, Meule said in an email.
Globally, almost 2 billion adults are overweight or obese, according to the World Health Organization. This increases their risk of premature death, breathing difficulties, cardiovascular disease, diabetes, hypertension, fractures and mental health issues.
The study, by Larissa Ledochowski at the University of Innsbruck in Austria and colleagues, examined the impact of a 15-minute treadmill walk on sugar cravings in a group of 47 overweight people who were on average about 28 years old.
To elevate sugary snack cravings, participants were asked to abstain from eating any sweets for three days at the start of the study. They were also asked to fast, drink nothing but water, and avoid any exercise for two hours prior to each assessment of cravings.
Then, in an exercise session, some participants warmed up for two minutes slowly on a treadmill then walked for 15 minutes at a pace fast enough to catch a bus, but not to the point of breathlessness.
For comparison, other participants, instead of exercise, were told to sit passively for 15 minutes without doing anything.
After exercising or sitting still, all of the participants sat quietly for five minutes. Then, they did a computerized test designed to boost physiological arousal and stress. Next, they were asked to unwrap a piece of candy and hold it without eating it.
Throughout the process, participants were questioned seven different times about their food cravings and their feelings of arousal or stress.
Those who exercised reported significantly lower cravings for sweets mid-way through the experiment and at the end than the participants who didn't get on the treadmill.
Even when people unwrapped candy and held it in their hands, people who exercised first had fewer cravings than those who didn't.
The study is small, and its limitations include relying on people to tell the truth about abstaining from sweets before the start of the experiment and a lack of measurements to track how much exertion was required by each participant to walk on the treadmill.
They were also exercising at a fairly low intensity, said Margaret Schneider, a researcher at the University of California, Irvine.
"The study only looks at the short-term impact, so we really shouldn't draw any conclusions about how one 15-minute exercise bout would impact eating behavior throughout the day," Schneider, who wasn't involved in the study, said in an email.
Even so, exercise does have the ability to improve mood, and it's possible that this could result in reduced cravings among individuals who eat for emotional reasons, she said. At the same time, mild exercise can also trigger metabolic processes that make more blood sugar available to the brain, reducing the craving for sugary foods.
And the study offers a reason to consider working at a treadmill desk, also known as walking work stations, Schneider said. "Presumably, remaining active at a low intensity throughout the day will result in less snacking and enhanced mood among the overweight."
Keeping healthy snacks on hand will also help exercise have the intended effect on food choices, Meule said. "Otherwise, temporarily reducing food craving by brisk walking will be ineffective. Even if people successfully manage to control their food cravings, they still have to eat something."