I have often suggested that taking a walk a short time after eating a meal is a good way to improve overall glycemic control by directly impacting the post-prandial (after-meal) effects of glucose and insulin. A new study from Mayo Clinic has done a great job of showing how large an impact this might actually have. In order to get this data, however, they required volunteers (healthy controls and Type 1 diabetic subjects) to wear special suits and monitors that recorded their every move and calorie expended for three days in a laboratory/clinic setting.
I will focus my attention on the control subject for this report. These subjects were normal weight (avg. BMI-25.6) and in their late 30’s (5 men, 7 women). Before testing the effects of walking on post-prandial glucose, they first recorded the energy expenditure of these subjects based on their activity- something that is important to note.
At rest (Basal metabolic rate/BMR): 0.84 kcal/h/kg
Standing 1.17 (40% increase over BMR)
Walking 1 mph 2.41 (186% increase over BMR)
Walking 2 mph 3.08 (266% increase over BMR)
Walking 3 mph 4.02 (378% increase over BMR)
Notice how much more energy is expended just when they begin to walk even at 1 mph, compared to being sedentary. For me, this data alone made the paper worth reading and another confirmation of why I am planning to install my new treadmill desk soon! Now back to the rest of the data.
Each of the 3 meals they consumed for the 3 days was virtually identical and contained 33% of their daily caloric needs. Meals consumed at 7 AM, 1 PM and 7 PM were 30% carbohydrate, 40% fat and 40% protein (no food was permitted outside these meals). Each day, one of the meals was followed by complete sedentary activity (lying in bed for 6 hours) and the other two meals were followed by bouts of walking (averaging 90-95 minutes before the next meal). While these activity levels seem a bit extreme, the metabolic differences were quite dramatic. When measuring the glucose excursion for 270 minutes after these meals, the amount was over twice us much (113% higher) when the subjects had no physical activity, compared to when they were walking (at only 1.2 mph!).
What does this mean for the average person? Well, the total distance walked after these meals was actually less than 2 miles. Most people can walk this in 40 minutes (at 3 mph) which is much more practical with a busy schedule. But more to the point, it tells us that any amount of physical activity, especially after a meal, improves glucose tolerance and reduces the level of blood glucose after eating. These numbers are likely to be even more striking in patients with insulin resistance eating higher carbohydrate meals than those tested here (i.e. the average American).
Think about how you can change your regular eating habits to allow for a walk afterward, or perhaps schedule your physical household chores to be accomplished right after eating supper so you can avoid plopping down on the couch or in front of the computer for several hours of sitting.
Here are some other similar recent studies you might find interesting:
- Breaking up prolonged sitting reduces postprandial glucose and insulin responses.
- Metabolism and performance during extended high-intensity intermittent exercise after consumption of low- and high-glycaemic index pre-exercise meals.
- Acute effects of shortly pre- versus postprandial aerobic exercise on postprandial lipoprotein metabolism in healthy but sedentary young women.
- High-intensity exercise attenuates postprandial lipaemia and markers of oxidative stress.
- Slow post-meal walking reduces postprandial glycemia in middle-aged women.