Exercise, Part 3: How Much Is Enough?

Now that you know the health benefits of exercise (see Parts 1 & 2 of this series), it’s a little easier to understand those crazy people you see jogging at 6 a.m. in below-freezing weather. I’m sure you’re ready to join them tomorrow morning. Right?

Here’s some good news. Most people following both the Ketogenic and Low-Carb Mediterranean Diets are able to lose excess weight and improve glucose control without starting an exercise program. Many—but certainly not all—will be able to maintain a stable, reasonable weight and glucose control long-term without ongoing exercise. However, for the reasons previously outlined, I recommend you start a physical activity program eventually.

Later in the series I discuss 1) who needs to get medical clearance from their personal physician before starting an exercise program, and 2) how certain diabetic complications make exercise more dangerous.

(I must warn you that athletic individuals who perform vigorous exercise should expect a deterioration in performance levels during the first three to four weeks of any very-low-carb ketogenic diet. The body needs that time to adjust to burning mostly fat for fuel rather than carbohydrate. Also, competitive weight-lifters or other anaerobic athletes (e.g., sprinters) will be hampered by the low muscle glycogen stores that accompany ketogenic diets. They need more carbohydrates for high-level performance.)

How Much Exercise?

All I’m asking you to do is aerobic activity, such as walk briskly (3–4 mph or 4.8–6.4 km/h) for 30 minutes most days of the week, and do some muscle-strengthening exercises three times a week. These recommendations are also consistent with the American Diabetes Association’s Standards of Care–2011. This amount of exercise will get you most of the documented health benefits. It’s OK if you want to wait until you’ve lost some of your excess weight, but I probably wouldn’t.

For the general public without diabetes, the U.S. Centers for Disease Control and Prevention recommends at least 150 minutes per week of moderate-intensity aerobic activity (e.g., brisk walking) and muscle-strengthening activity at least twice a week, OR 75 minutes per week of vigorous-intensity aerobic activity (e.g., running or jogging) plus muscle-strengthening activity at least twice a week. The muscle-strengthening activity should work all the major muscle groups: legs, hips, back, abdomen, chest, shoulders, arms.

Please note that you don’t have to run marathons (26.2 miles) or compete in the Ironman Triathlon to earn the health benefits of exercise. However, if health promotion and disease prevention are your goals, plan on a lifetime commitment to regular physical activity.

Parts 4 & 5 of this series review strength training and aerobic exercise.

Steve Parker, M.D. 


Filed under Exercise

3 responses to “Exercise, Part 3: How Much Is Enough?

  1. I wish I had my ACSM news letter here at home. It recently had an article describing the effect of 2 weeks bed-rest on healthy (very active) young adult males. After their two weeks of no exercise their glucose tolerance was much lower, and even after several months of reconditioning their glucose and insulin levels were still not back to base line. Thought you might find that interesting. I’ll try and find the article.

  2. wartson

    Metformin has been shown to be particularly beneficial in reducing the risk of death due to the complications of diabetes in overweight and obese patients, who are especially prone to developing diabetes. However, there has been some concern regarding the potential safety of metformin in patients with preexisting cardiovascular disease and kidney disease, and so this first-line diabetes medication has not been extensively prescribed to diabetic patients with these diseases.

  3. Well, this is very much interesting indeed. Would love to read a little more of this. Great post. Thanks for the heads-up.