Wednesday, January 19, 2011
Running for Weight Loss
By Rita Klabacha, M.S.
Many people use running as a means to weight loss. Running is a sure fire way to drop all that unwanted fat, right? Possibly, but not necessarily. Starting a running program, for any reason, is a great thing! But there are some things to keep in mind if your primary goal is weight loss through running.
When it comes to weight loss, we intuitively accept the theory “calories in v. calories out.” That is, expend more calories than you consume. In the healthy person, someone without any true metabolic disorder or other health-related issues, this equation works. In my experience, the majority of people who insist they’ve “tried everything to lose weight but just can’t,” are unaware of three important bits of information about themselves. I ask the following three questions of individuals who fall into this category:
1) How many calories do you consume each day?
2) How many calories do you expend each day?
3) How many calories do you need each day?
Studies again and again have shown that the average person regularly underestimates calorie intake and overestimates caloric expenditure. When it comes to caloric need, most people either have no idea, or tend to swing toward highly restrictive diets, especially if they’ve spent years in that very common pattern of rapid weight loss that eventually results in excessive weight gain. Unfortunately, very-low calorie restrictive diets DON’T work in the long-term, and are detrimental.
On the flip side, just because you’ve started a running program, don’t succumb to the belief that now you can eat anything you want! Knowing how many calories you expend during exercise can be problematic. First, understand that intensity matters. If you’re running slower than a 9-minute mile and weigh 150 lbs, you’re expending up to 350 calories for a 30-minute sustained run (less if you’re running slower). On the other hand, a 150 lb runner who is running a 6-minute mile expends closer to 575 calories during that same 30-minute run.
If you know how to read a food label and use a food scale, it is relatively easy to determine your daily caloric intake through tracking with a food diary. Figuring out accurately how many calories you need daily AND expend through exercise, can be more of a challenge. The most accurate method is through clinical metabolic testing. Having your Basal Metabolic Rate (BMR, sometimes also referred to as Resting Metabolic Rate) measured, as well as having your exercising metabolic rate measured during steady state exercise, will give you caloric expenditure at rest and exercise, and thus caloric intake needs at rest and during exercise. These types of measurements can often be made at a sport medicine clinic, or university. We offer such testing at the Mammoth SPORT Center. A less accurate yet simpler method is through use of the Harris-Benedict Equation. First, estimate your BMR by applying the appropriate calculation for your gender:
Women: 655.1 + ( 9.563 x weight in kg ) + ( 1.850 x height in cm ) – ( 4.676 x age in years )
Men: 66.5 + ( 13.75 x weight in kg ) + ( 5.003 x height in cm ) – ( 6.775 x age in years )
Then, apply your activity factor to estimate daily calories needed:
Little to no exercise: BMR x 1.2
Light exercise (1–3 days per week): BMR x 1.375
Moderate exercise (3–5 days per week): BMR x 1.55
Heavy exercise (6–7 days per week): BMR x 1.725
Very heavy exercise (twice per day, extra heavy workouts): BMR x 1.9
You may need to tweak these numbers a bit to find your ideal needs. Good luck and let me know how this works for you!