On my way to work yesterday, I picked a colleague who has been trying to lose weight to control her high Blood Pressure. She has borderline hypertension for which her doctor had advised lifestyle modification: physical exercise and diet control. She said she has controlled her diet which includes reducing of salt, fat and sugar intake. She said she has daily exercise as she walks long distance to take her child to school. She must be walking a minimum of 2 km daily. But her weight is not coming down.
I’m sure many people can relate to her story. One important question to ask here is, ‘how much exercise does it require to lose weight? (I am not saying exercise is the only factor). For maintenance of health, it is recommended that adults exercise for 30 minutes a day for 5 days a week, or 150 minutes per week. For weight reduction, it is recommended to exercise for 60 minutes a day and not 30 minutes which is only for maintenance. Interestingly one study found that 30 minutes is as effective as 60 minutes. This is good news for a lot of people who would feel that they don’t have 60 minutes to spare. The more important question, however, is ‘What should be the intensity of the exercise?’ I think this is where we fail to get the right benefit out of exercise.
We lose weight through exercise by burning of calories. If we reduce calorie intake and also burn calorie through exercise, there is a calorie deficit which results in weight lose. By this mathematical equation, if we don’t reduce calorie intake or burn calorie sufficiently, a calorie deficit cannot be created. That means if we don’t control our diet or the exercise is not intensive enough, we cannot lose weight. The type of exercise which is recommended is moderate to vigorous intensity exercise. How do we know we have achieved this?
Centre for Disease Control (CDC) says that an exercise is moderately intense if the exercise you are doing results in breathing and heart becoming noticeably faster but you can still carry on a conversation. Such activities include walking briskly (5.6 km/hr), climbing, gardening, dancing bicycling (less than 16 km), playing with children etc. In the case of my colleague, walking a child to school may not be intensive enough to reap the benefit. Vigorous exercise is defined as the exercise by which heart rate increased substantially and breathing too hard and fast to have a conversation. Examples are running, jogging (8 km/hr), bicycling (more than 16 kms per hour), swimming, brisk walking (7kms per hour), weight lifting (vigorous effort) & competitive sports, digging & cutting wood, etc. So, to have vigorous exercise is to have it so hard that you are out of breath.
As you can see, brisk walking features both in moderate and vigorous categories and are differentiated only by the speed. Research study shows that brisk walking is as effective as jogging or running to reduce weight. This is also good news for people who have difficulty to run to start with.
Below are the major benefits of exercise:
- Vigorous physical activity reduces risk of breast cancer by approximately 20 to 40 %
- Risk of type 2 diabetes can be reduced by 60% through physical activity. Physical activity improves control of blood glucose.
- Risk of coronary heart diseases is 30 to 50% higher in people who do not involve in moderate level physical activity.
- Physical activity reduces blood pressure & improves good cholesterol. A single session of physical activity decreases blood pressure level for up to about 20 hours. Moderate amount of activity decrease risk of stroke.
- Physical exercise improves mental health.