Commuting by bike & weight loss…

In news that will surprise nobody, this week another study has found that people who don’t drive to work stay slimmer.

Up there with such profound questions as “do bears defecate in the woods?” and “if a tree falls in the forest and there’s nobody around to hear it, does it make a sound?” the question of whether people who exercise on their way to and from work have lower levels of body fat, has once again been answered.

People who cycle, walk or catch the train or bus to work keep more weight off than commuters who travel by car, a large UK study has found.

Source: Commuters who shun car travel keep slimmer, study concludes – BBC News

In all seriousness, whilst it is true that those who cycle or walk to work stand a better chance of keeping the weight off, it isn’t always that cut & dried.

CAUTION! Cliché Ahead!

There’s a saying: You can’t outrun a bad diet. This is indeed true and just because you cycle or walk to work, it doesn’t mean that you can eat what you want and still lose weight.

The length and intensity of your commute will dictate just how many calories you burn on that commute, but if those calories are made up of the wrong sorts of foods that lack the various nutrients that an active body needs to stay healthy and to repair the muscles damaged through exercise (don’t worry, it’s the good sort of damage!), you will struggle to maintain that level of activity.

The upshot of this is that you’ll either “bonk” on your ride home, having depleted your glycogen stores & go all wobbly and faint, or you’ll struggle to stay motivated and end up taking the lazy option.

High Carb vs Low Carb

There’s little doubt that our often sedentary lifestyles are a contributing factor in our increasingly spherical population, but confusion over diet caused by a generation of one-size-fits-all but fundamentally flawed advice probably hasn’t helped.

During the 90s we were told that “fat is bad” and that we should avoid things like butter and fatty foods. As it turns out, this was probably the wrong advice for a great many people. You see, fats are great sources of slow burning energy and, they have a relatively low insulin response compared to high carb & sugary foods.

Carbs are great sources of fast-burning fuel, ideal for cycling around like someone who has disturbed a hornets nest. However, many of us spend our days sat at desks, not really doing very much. The trouble is, these carbs are still burned quickly –anyone who eats mostly breakfast cereals or toast in the morning will tell you, they’re probably hungry again an hour later.

You eat and your body responds by producing insulin to start the process of absorbing this energy, or glycogen into the cells that need it. Crucially, anything left over is turned to fat and stored. Your body processes carbs in double-quick time, turns what it doesn’t need into fat and then tells you that you’re empty again and need more fuel, so you eat again.

Fatty foods like meat, eggs & dairy are also burned to produce energy, but it takes a lot longer, reducing the need to eat again shortly after.

However, whether you eat a low carb or high carb diet, you need to balance the calories you consume with the ones you are using. You do need carbs often during and definitely after exercise to replace your glycogen stores, but if you are at work all day having taken the train or car to work, you are arguably better off on meat & dairy (or nuts, legumes & other sources of protein & fats if you are vegetarian).

Your daily intake target

We are told that our daily calorie intake should be 2500 for men and 2000 for women, but in both cases this is based on someone who has a reasonably active lifestyle. This seemingly arbitrary figure is derived from calculating your BMR, or your Basal Metabolic Rate and multiplying it with another number.

Your BMR is “the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting)”. Got that?

Your body consumes calories just by being alive. Your brain needs a lot of energy to run, as does your heart and other organs. They’re just ticking along doing what they do whether you are moving about or not.

You then need to add on calories according to your level of physical activity. To do this, you need to multiply your BMR by:

  • 1.2 if you are not very active
  • 1.375 if you are somewhat active
  • 1.55 if you do some exercise during the week
  • 1.95 if you do a lot of sport


Using myself as an example, my BMR is around 1600 calories, but if I multiply that by 1.55 as someone who does some exercise during the week, I get a figure of 2500(ish). That would be my daily calorie target and very close to what is commonly recommended. On that basis it is easy to see where we have been going wrong.

Giving everyone an arbitrary calorie goal on the assumption that we are all active is going to lead people to put on weight.

If I didn’t cycle to work my daily target would be just under 2000 per day. That’s pretty much a whole meal less…

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