Wednesday, January 23, 2013

Intense Exercise Reduces Appetite ...

Well that was a pretty intense workout this morning, eh!?

How are you feeling? 

Hopefully, you're feeling energized and ready to tackle whatever life has in store for you today.

According to emerging research, one thing you probably shouldn't be feeling after a hard workout is hungry!

Let's take a look at two studies ...

New research out of BYU shows that 45 minutes of vigorous exercise in the morning actually reduces a person's motivation for food.

Professors James LeCheminant and Michael Larson measured the neural activity of 35 women while they viewed food images, both following a morning of exercise and a morning without exercise.  They found their response to the food pictures decreased after working out.

"This study provides evidence that exercise not only affects energy output, but it also may affect how people respond to food cues," LeCheminant said.

The study, published in the October issue of Medicine & Science in Sports & Exercise, measured the food motivation of 18 normal-weight women and 17 clinically obese women over two separate days.

The 45-minute exercise bout not only produced lower brain responses to the food images, but also resulted in an increase in total physical activity that day, regardless of body mass index.

"We wanted to see if obesity influenced food motivation, but it didn't," LeCheminant said. "However, it was clear that the exercise bout was playing a role in their neural responses to the pictures of food."

In another study facilitated by David Stensel, Ph.D., at Loughborough University, research shows that exercise may lower levels of ghrelin, a hormone that stimulates appetite, while raising levels of peptide YY, a hormone that suppresses appetite.  But Dr. Stensel is quick to point out that exercise's impact on appetite hormones are only present if the workout is intense ("if you can chat", he says, "forget it"). 

According to the study the more intense the workout is, the longer the benefit seems to last. "It may be that your body needs to circulate more blood to prevent overheating," Stensel explains. Because eating would cause blood to flow to the stomach instead to aid digestion, your body dampens your appetite to prevent that.

Interesting stuff, for sure.

I was talking with a boot camper yesterday on this vary topic.  She and I both experience similar effects. 

When I do an easy 30 minute workout, which I'll do on days I need recovery from a particularly hard workout (like running a half marathon), I tend to feel hungrier and eat more.

On days I'm sprinting, doing fast track intervals, running hills, performing heavy squats where I'm out of breath, or doing a Tabata ... my appetite is measurably reduced, and overall I eat less.

So the take home based on these 2 studies - working out intensely first thing in the morning has both a psychological and physiological impact on food consumption.  See if this is true for you as well - pay attention to your appetite (track in a journal) on days that you workout hard versus days that you don't work out.  My guess is you'll have a similar reduction in appetite - which is helpful if losing body fat is one of your goals for 2013!

Your friend in fitness,

Brian Calkins

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