Should I eat before or after my exercise?

Question

I work from home quite often so don't get enough natural exercise, recently I decided to take a fast paced walk early in the morning to simulate the usual walk to work.

I'm not sure if I should have breakfast before or after my walk, here are the facts:

• I walk 3.8 miles
• It takes 55 mins
• Breakfast is 1 hot cross bun and butter
• I walk at the same speed, and same distance in either case

My thinking is that if I have breakfast first, then my body won't burn any fat, only the calories from my breakfast. However, if I have breakfast after, then my body should be burning fat instead.

When I google this subject the results are just concerning stomach upsets and getting the most out of your workout, neither apply to my case.

What should I do?

Answer 1

Zoomed out a bit, I'd look at the other 23 hours a day and realize that your 14 minute/mile walk (while certainly better than nothing) isn't really going to have a huge dent on your daily caloric intake. Additionally, a sugar laced mound of carbohydrates doesn't really fit into a solid nutrition plan on a daily basis.

That bun, because of the sugar and refined carbohydrates, is causing your insulin levels to spike, which is causing your fat cells to accelerate their grabbing-fuel-from-the-blood process and pack it away in your fatty tissues.

Forgetting about all of that for a minute, and answering your question directly:

However, if I have breakfast after, then my body should be burning fat instead.

Your body can store several thousand calories worth of sugar in your blood and liver. If you have a typical high carbohydrate (and high calorie) diet like most of the western world, your body has very little reason to use up its fat reserves because you're constantly supplying it with a steady stream of sugar/carbs.

When you go for a walk in the morning, you are using up some fat, no doubt. But the bulk of your energy demands are being met (probably) by the glycogen reserves that are sitting in your blood and liver from dinner and lunch the day before.