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The type of exercise you choose to do affects how hungry you feel afterwards, says new research that reveals how some workouts trigger cravings for healthy food such as fruit while others lead to a desire for chocolate.
According to a study by Dr David Stensel, Britain's leading expert on sport and exercise science, a long swim in a cold pool can leave you hungry, wanting high-fat foods such as biscuits, while running on a warm day has the opposite effect.
"Some people are concerned that exercise will make them want to eat more, but the good news is that there doesn't necessarily have to be that compensation," said Stensel.
"While some high-intensity exercise, such as running in hot conditions, suppresses the ghrelin hormone, which stimulates appetite, other high-intensity exercise, such as swimming in cold water, actually increases the hormone which, in turn, increases hunger. Medium-to-low-intensity exercise, such as walking, has no impact on ghrelin, meaning you are as hungry after a one-hour walk as you are if you sat in a chair for the same period of time."
Stensel is studying possible causes for these results, published in his book Influence of Resistance and Aerobic Exercise on Hunger, but said one cause could be the effort the body makes to keep its core temperature stable.
"When exercising, the priority of the body is to divert as much blood to the muscles as possible, which takes it away from the digestive functions. An additional cause could be that when you are hot, you need to release that heat by circulating blood to the skin, which also takes it away from the stomach and intestines. The opposite happens when you are cold."
Stensel also suggested the cravings could be psychological. The suppression of appetite lasts until the body's hormonal levels return to normal, usually between one and three hours later.
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