Exercising in a fasting state - during the holidays

This article was sent to me by my sister - Phys Ed: The Benefits of Exercising Before Breakfast

I have mentioned that last year was the first and only year that I have actually lost weight over the holidays. The reason for this was a lot of run volume while training for my first (stand alone) marathon. I had a line in the sand and an aggressive goal time (BQ). I also truly believe that when it comes to running – light is right. Most references note that you can increase your speed by about 2 seconds per mile per pound. For example, 5 pounds could reduce your running pace by 10 seconds per mile - in a marathon that could over 4 minutes (a 3:04:00 marathon is 7:02 pace while 2:59:59 marathon is 6:53 pace). So, last year with this aggressive running goal I was able to not only maintain my weight but lose a little bit of body fat.

For the study, researchers in Belgium recruited 28 healthy, active young men and began stuffing them with a truly lousy diet, composed of 50 percent fat and 30 percent more calories, overall, than the men had been consuming. Some of the men agreed not to exercise during the experiment. The rest were assigned to one of two exercise groups. The groups’ regimens were identical and exhausting. The men worked out four times a week in the mornings, running and cycling at a strenuous intensity. Two of the sessions lasted 90 minutes, the others, an hour. All of the workouts were supervised, so the energy expenditure of the two groups was identical.

Their early-morning routines, however, were not. One of the groups ate a hefty, carbohydrate-rich breakfast before exercising and continued to ingest carbohydrates, in the form of something like a sports drink, throughout their workouts. The second group worked out without eating first and drank only water during the training. They made up for their abstinence with breakfast later that morning, comparable in calories to the other group’s trencherman portions.

The experiment lasted for six weeks. At the end, the nonexercising group was, to no one’s surprise, super-sized, having packed on an average of more than six pounds. They had also developed insulin resistance — their muscles were no longer responding well to insulin and weren’t pulling sugar (or, more technically, glucose) out of the bloodstream efficiently — and they had begun storing extra fat within and between their muscle cells. Both insulin resistance and fat-marbled muscles are metabolically unhealthy conditions that can be precursors of diabetes.

The men who ate breakfast before exercising gained weight, too, although only about half as much as the control group. Like those sedentary big eaters, however, they had become more insulin-resistant and were storing a greater amount of fat in their muscles.

Only the group that exercised before breakfast gained almost no weight and showed no signs of insulin resistance. They also burned the fat they were taking in more efficiently. “Our current data,” the study’s authors wrote, “indicate that exercise training in the fasted state is more effective than exercise in the carbohydrate-fed state to stimulate glucose tolerance despite a hypercaloric high-fat diet.”

You can read the actual study here.

Exercising in a fasted state has been debated on countless exercise forums. There are a number of opinions ranging from burning more fat to the wasting of lean muscle mass. This study only reports what happened to these individuals when on an increased calorie, high fat diet (like the holiday season). It did not study what the effects are on a normal diet – well, normal for us – I hope we do not eat a holiday diet year round.

I routinely exercise in the morning; I simply just don’t get up early enough to have a meal before hitting the pavement. I think for more intense sessions (running intervals or cycling time trails) this can be a liability but for moderate intensity up to and including tempo work this fasted state is effective. I do not notice an inability to perform my workouts as long as the duration is less than 90 minutes.  For a race, I get up early and have my oatmeal.

Another benefit of running before breakfast is that it does not matter what happens the rest of the day – I have already done my workout.

Pay yourself first and then go have a (light) breakfast.