Kidney Health Weight Management Wellness

A Kidney Doctor’s Guide to Weight Loss

September 15, 2010

A Kidney Doctor’s Guide to Weight Loss

Most of us believe that burning more calories leads to weight loss. Although a true statement, in turns out that recent research suggests we change our focus. Instead of calories burned, we need to think about Mets (Metabolic Equivalents), target heart rate, and time spent exercising at a moderate level of intensity. In this context we decide our weight management goal: weight maintenance, slow weight loss, faster weight loss, or prevention of previously gained weight.

The recent research comes from the American College of Sports Medicine. The old exercise recommendation was 30 minutes, 3 times a week. The new, more challenging recommendations require much more work:

  • To maintain your current weight:
    • moderate intensity physical activity of 150 minutes per week to prevent significant weight gain and reduce chronic disease factors associated with inactivity and being overweight.
      • 150 minutes / 7 days = 22 min/day
      • 150 minutes / 5 days = 30 min/day
  • To lose rate slowly:
    • The ACSM recommends that 150 minutes of moderate intensity physical activity per week is also sufficient in most individuals to result in modest weight reduction.
  • To lose weight more quickly or to prevent regain of previously lost weight:
    • the ACSM has updated its position to recommend 250-300 minutes of moderate intensity, weekly physical activity for more significant weight loss and preventing weight from being regained.
      • 300 minutes / 7 days = 43 min/day
      • 300 minutes / 5 days = 60 min/day (that is 1 hour daily!)

So now that we know the recommendations, our next step is to standardize the energy expenditure among various common exercises so that regardless of which type of exercise you chose, you are exercising at moderate intensity. And that’s what metabolic equivalents are for!

In simple terms, a metabolic equivalent can be defined as the amount of energy expended during a particular exercise compared with how much energy the body burns while resting. Consider “resting” as 1 metabolic equivalent. Although, we burn calories sitting in front of the television (binging on potato chips excluded from the calculation), the amount of energy expended is considered to be 1 met. Different activities such as walking, bicycling, and jogging burn more calories than resting. For instance, using a stationary bicycle with light effort equates to 3 mets, or 3 times the amount of energy the body expends during rest.
Your goal is to participate in an activity and modify your effort so that you are at 3-6 metabolic equivalents which defines moderate intensity exercise.

A better approach is using an exercise machine that gives you real time metabolic equivalent numbers. Modern treadmills, stationary bikes, steppers and other exercise equipment have them. The treadmill allows for increased elevation and speed to increase the number of mets if necessary to achieve goal.

Now you know your energy expenditure goal. However, you must “listen” to your body and make sure that you are exercising at 50-85% of your target heart rate.

Just like metabolic equivalents, you should consider real-time heart rate feedback. Consider using devices that give you your heart rate. For example, the exercise machines at the Y tell you your heart rate in real time. The CHI Health Lakeside Wellness Center also has similar machines.

The next “step” is to determine your daily exercise time. This amount of time is based on your goals as stated above and how many days per week you plan to exercise. I personally strive for 60-90 minutes, 5-7 days a week.

Although not described in the title of this medblog, the final part of exercising safely is to assess what your perceived amount of exertion is so that you don’t overdo it. I use the Borg RPE scale to help determine this “perceived amount of exertion.” You don’t want to hurt yourself, and this scale helps you define your limits.

In my opinion, in order to achieve your weight loss goal you need to be 12-14 on the Borg RPE Scale while at the same time attain the objective measures stated above. In other words, even though the mets may be less than 3, and the heart rate may be less than 85% of target; if you perceive your exercise level is 16 or 17 (too high), you may need to spend time conditioning your body so that you can tolerate moderate intensity physical activity based on the objective criteria above. Because once you perceive that you are exercising “very hard,” pushing yourself above that level or maintaining your current level of exertion may lead to physical injury. On the other hand, if you think your current work out is “very light” (9 on the Borg Scale), you may want to increase the intensity of your workout.

After moving down to Omaha, Nebraska and starting a very successful nephrology practice with CHI Health, I gained weight. I’m on call every other night, and the job is stressful. People who work shifts are at increased risk for weight gain, unfortunately. Also, my little ones love to play and get involved which can make exercising safely at home a challenge. That’s why my wife and I joined the Y. Although aware of the concept of “mets” and the recently updated recommendation changes for exercise, I really didn’t “get it” until I pushed the button on the treadmill at the Y that says “mets.” With further investigation, I realized I need to push the heart rate button as well.  I developed this new way of thinking which has been successful for me, and I wanted to share it with you. I now focus on the important data during my work-outs to get the greatest return on my exercise investment.

Feel free to use this information to plan an exercise strategy that works for you.

Please note: before initiating an exercise program, consider consulting your primary care medical doctor. 

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