Calories Burned Changed for Same Exercise and Duration

cgibson522

I've been logging a 45 minute exercise each day using the same exercise type and duration. I noticed today that the number of calories burned has decreased from what it's been previous days. I have lost a few pounds - does exercise burn fewer calories the less heavy you are?

bpetrosky

The calorie burn estimate for exercises like walking or running are dependent on your body weight, so if you've logged some weight loss it would affect the number.

MHarper522

Just think of it this way: it takes more energy to carry a 50 pounds bag than a 30 pound bag. The calorie burn for the same exercise will definitely go down as you lose weight, as will the number of calories you burn just by being alive and going through your day.

FlyingMolly

Yep. It also takes (slightly) fewer calories just to keep your body running at all, so your regular calorie allowance will decrease a bit at a time as you lose weight. It is, in the grand scheme of things, not the WORST problem to have.

NorthCascades

If you were cycling, your speed has a profound impact on your calorie burn because air resistance goes up with the cube (?) of speed.

NorthCascades

^ Somebody who doesn't understand basic physics woo'd this.

sijomial

"I've been logging a 45 minute exercise each day using the same exercise type and duration. I noticed today that the number of calories burned has decreased from what it's been previous days. "
That's because the exercise database uses METS multipliers based on your weight.

"I have lost a few pounds - does exercise burn fewer calories the less heavy you are?"
Only if:

• It's a weight bearing exercise.
• You are doing exactly the same amount of work (work in the physics sense).

If you run the same 4 miles in that 45 minutes then being lighter will indeed mean a reduced calorie burn.
But if you are now fitter and are running 4 miles instead of 3.5 miles you could previously manage you would no doubt be burning more.

As a generalisation fitter and stronger people will have a higher calorie burn from exercise so weight and duration is often not a great way to get good estimates.
My maximal exercise calorie burns have gone up by about 25% despite losing a sixth of my body weight.

Your weight does have a more reliable impact on your BMR and daily activity (as opposed to exercise) though.