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Runner's Corner
Fat Burning
May 2008 Runner’s Corner
By Kitty A. Consolo, Ph.D.
Overweight versus Overfat
Now that it’s May and we can run in shorts again, some of you might be thinking about burning off some of the winter pounds. Keep in mind though that it’s not how much you weigh but how much body fat one has that is a health issue. Thus avoid the scales and concern yourself with clothing sizes. If you want to be more scientific, visit an exercise physiology lab at a major university (such as OSU, OU, Kent State) and ask to have your body fat professionally measured. Women want to be above 12% but less than 30% while men should be above 5% but less than 25%. We have an obesity epidemic in thus country but if you run, you’ve got a great way to manage body fat. Also keep in mind that as you run, your body builds muscle, blood volume, muscle glycogen stores and bone, all of which weigh more than fat. So if you only go by the scales you may not see a loss in weight even though your body is losing body fat, hence have your body fat measured or see if your clothing sizes are going down.
Fat Burning Workouts
Long Runs
There are two workouts that help burn fat. Keep in mind that the body has to have oxygen present to burn fat, thus those long slower distance runs are ideal for burning fat as well as stored glycogen. Thus if you don’t have a long run in your week, start adding one but go slow, add just 1 to 2 miles a week until you get up to 1 hour or more, 60-90 minute workouts are ideal for burning fat.
Intensity Workouts: Intervals or Tempo Runs
I just told you that the body needs oxygen to burn fat. When we work out at a high intensity above 70% of our effort, our muscles rely on glycogen for energy instead of fat because at that intensity it is too hard to burn the fat and have enough oxygen present in the muscle cell (we always have oxygen for our brain etc). However, after we do a hard interval such as a mile repeat or a tempo run, during the recovery period, our body burns more fat than if we just did a short slow run. These workouts also help you get faster as a runner, but keep in mind they can also cause you to risk injury or illness. Hence limit these workouts to once a week and to about 10-20% of your total time or miles run. If you are running a race that week, skip the intense workout.
Fats Burn in a Carbohydrate Flame
Metabolically, in order for the body to burn fat, it also has to have a balanced diet of carbohydrates, fats and proteins. As a runner, the majority of your intake of food should be healthy carbohydrates—fruits, vegetables and grains and should make up anywhere from 50% to 75% of your total calories. See a sport nutritionist for more details. If you follow a low-carb diet such as Atkins or the Zone, you will not have enough carbs to help your body burn fat. Worse yet, the brain and nerve cells will crave carbohydrate and start breaking down your muscles (including your heart) to get glucose even if you have lot’s of excess body fat because excess body fat can not provide glucose. There is a special cycle in the body called the glucose alanine cycle that allows the body to convert protein into sugar but this is NOT healthy! This is what happens to anorexics and people with eating disorders and can lead to muscle wasting, heart damage or death! So load up on the good carbs and avoid any low carbohydrate diet as a runner. These low carb diets also deplete the body of water because for every gram of carbohydrate you store, you store 3 grams of water with it. Thus, depleting the body of carbs depletes the body of water and leads to rapid water loss and weight loss which is also very unhealthy.
Protein intake should be around 10-15% of your total calories and fat should be around 30% with care taken to limit saturated fats (from animal products) to 10% or less.
Eat Small Frequent Meals
Another factor that helps our metabolism and keeps us burning fat is to constantly feed the body with small healthy meals. An ideal day would be a breakfast, snack, lunch, snack and dinner and possibly a small snack later depending on dinner size. The body maintains glucose levels more efficiently and burns calories better if you are eating small frequent meals every few hours instead of going several hours without eating in between meals. If you plan to run within a few hours of a meal, make that meal primarily carbs and then eat your protein and fat meals once your run is done.
Summary
Running is a great way to maintain healthy body fat, but it helps to have one long run day and one speed day so that the body gets challenged to increase it’s metabolism and burn fat, rather than get used to doing the same daily runs. Monitor fat loss by working with an exercise physiologist who can measure body fat or go by your clothing size rather than the scales which can not tell you if you lost fat weight. Be sure to get in lots of healthy carbs and avoid low-carb diets. They not only result in muscle burning but also dehydrate your body. And try eating small frequent meals, this schedule will boost your metabolism and give you more stable blood sugar levels and energy.
Hope to see you on the roads, running lean…Kitty
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