Planners, urbanists and those who advocate for walkable neighborhoods have done a really good job of giving overarching reasons why we need to increase the amount of walkable neighborhoods in our cities. One of the more obvious reasons why we need to increase them is health.
While it seems obvious, more walkability means more healthy citizens, where they haven't done a good job is getting into the whys, though it is beyond the scope of what they do. So I wanted to get into some detail on that, just why more walking is better for everyone.
Our bodies receive fuel from two sources, fat and carbohydrates. At its basic, the body converts fat into the energy it needs to operate. As I sit here and type this, as you sit here and read this, our bodies are burning fat, just to stay alive, as well as the small amounts of energy required to carry out those duties. Now, not very much fat is burned, so you can't claim to be working out by sitting.
The thing about fat is that it requires a lot of oxygen to convert to energy. That's why as we sit here, we breathe. It is also why as we exert ourselves more, we breathe faster and heavier.
It is at this point that our body switches to the second energy source. Carbs are a short-term energy source that do not require near as much oxygen to convert to energy. They are also not stored in any large quantities. If you have ever seen a bike race, the most popular being the Tour de France, they are constantly eating. The reason is to keep the carbs supply high enough to operate efficiently.
We most associate physical activity and muscle use with increased breathing, but it can be other parts of the body. If a person is sitting out in the mid-August sun with no shade, their body may switch to carbs to operate the cooling system because it is having to work a lot harder and also keep the vital organs going. At that point, they will start to breath faster, even though they aren't moving.
Unlike carbs, fat is able to be stored in very large quantities, in some cases beyond a reasonable health level. But the average person doesn't need large amounts of carbs, so the human body developed a system to store the energy we need. At some point, the body will convert carbs to fat and store the energy for future use.
Now the point at which the body begins the switching to carbs varies, but generally speaking, the better physical shape a person is in, the longer it takes. In other words, a person in good shape can run longer before the body switches. It is also important to note that just because you start to breath faster, doesn't mean the body has started the switch. It just means it needs more oxygen right now. Someone who is huffing and puffing is virtually guaranteed to be burning carbs, but one who is at a slightly elevated breathing level is likely to still be burning fat, just more of it than normal.
This is where walking comes in. The average person burns between 50 to 100 calories if they walk for 10 minutes and most people minus the exceptionally out-of-shape would burn fat to fuel that walk. If we lived in more walkable areas, going to run minor errands would not only accomplish the task, but burn fat, since that is likely the fuel source used at low levels of exertion.
An extra ten minutes of walking a day, taken out over the course of a year, using a conservative 65 calories per walk, would burn a total of 23,725 calories. One pound of fat equals 3,500 calories, so walking an extra ten minutes a day would equate to a loss of almost seven pounds a year.
Now imagine if that came out of doing day-to-day things, instead of having to find the time to walk. Replacing neighborhoods that require a car with one where it is one of many options has a huge health benefit. Just living in a more walkable neighborhood, and changing a lifestyle to match the neighborhood, would slim the waistline tremendously.