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I've investigated every device that claims to be able to accurately track calories expended and/or calories ingested. On the calories expended side, the clear

by iplaw 10y ago

I've investigated every device that claims to be able to accurately track calories expended and/or calories ingested. On the calories expended side, the clear winner is a power meter on a bicycle. The power meter measures actual power output and energy expenditure, which is easily and accurately converted to kCal. For the indirect devices, it's a massive mixed bag with some very unexpected observations. Measuring galvanic skin response ended up being quite inaccurate. Garmin devices without a heart rate strap were insanely inaccurate, sometimes reporting 300% higher-than-actual calories expended. The best device has actually been the Apple Watch paired with an iPhone. The calories reported are usually within 5% of actual. As for the devices claiming to track calories ingested, every device has been either outright fraudulent or, at best, vaporware.

pure_ambition 10y ago
Do you have any research to back this up? I'd love to see more about the methodologies and results you say.
anu7df 10y ago
I am sorry but I cannot see how the power meter on a bicycle is "accurate" in this context. I am not trying to measure the part of the energy expended to run the cycle (which the power meter accurately measures) but the total energy expended by me while biking.An example; what if I put on some ankle weights while biking. How does the power meter know that? To explain with an almost farcical extreme example, if I attach a power meter to a step/chair while doing a step up step down exercise, it will register zero calories burned always. But I would most certainly be burning calories doing the exercise.
- iplaw 10y ago
  You're not understanding how the power meter works. Nor did I say that a power meter can be applied to every possible workout or piece of equipment. In your ankle weight scenario, the added weight would, in effect, cancel out. You'd get a free boost to power output for 50% of a pedal stroke, and added resistance to the other 50% of the pedal stroke. These forces are being applied simultaneously on either side of the cranks. While one side is combating the added weight, the other side is feeling the boost of the additional weight. And sure, there are additional caloric expenditures while cycling - increased heart and respiration rate, utilization of muscles in your arms and torso, etc. - but they are marginal compared to the generation of 300-400W using, primarily, the muscles in your lower body. Further, these differences are factored into the athlete's efficiency in turning calories into mechanical output. A trained cyclist is 25% efficient. You seem to be attempting to be deliberately obtuse.
rmm 10y ago
power generated on a power meter is by no means accurate measure for personal energy expenditure. Unless of course you are machine running at 100% efficiency. (The only 24% efficiency factor for humans is based on so many assumptions) Only real way to measure energy expenditure accurately is using breathing measurements. VCO2/VO2
- iplaw 10y ago
  A trained cyclist is roughly 25% efficient, and 1 kCal = 4.184 kJ. The power meter precisely measures kJ. The end result is a near 1:1 ratio between kCal burned and kJ measured. Sure, the power meter under reports total expenditure. For example, it doesn't exactly account for BMR, increased expenditure due to elevated heart and respiration rate, utilization of muscles in your arms and torso, etc. However, it is extremely accurate compared to the alternatives.

by iplaw 10y ago

pure_ambition 10y ago

Do you have any research to back this up? I'd love to see more about the methodologies and results you say.

anu7df 10y ago

I am sorry but I cannot see how the power meter on a bicycle is "accurate" in this context. I am not trying to measure the part of the energy expended to run the cycle (which the power meter accurately measures) but the total energy expended by me while biking.An example; what if I put on some ankle weights while biking. How does the power meter know that? To explain with an almost farcical extreme example, if I attach a power meter to a step/chair while doing a step up step down exercise, it will register zero calories burned always. But I would most certainly be burning calories doing the exercise.

iplaw 10y ago
You're not understanding how the power meter works. Nor did I say that a power meter can be applied to every possible workout or piece of equipment. In your ankle weight scenario, the added weight would, in effect, cancel out. You'd get a free boost to power output for 50% of a pedal stroke, and added resistance to the other 50% of the pedal stroke. These forces are being applied simultaneously on either side of the cranks. While one side is combating the added weight, the other side is feeling the boost of the additional weight. And sure, there are additional caloric expenditures while cycling - increased heart and respiration rate, utilization of muscles in your arms and torso, etc. - but they are marginal compared to the generation of 300-400W using, primarily, the muscles in your lower body. Further, these differences are factored into the athlete's efficiency in turning calories into mechanical output. A trained cyclist is 25% efficient. You seem to be attempting to be deliberately obtuse.

rmm 10y ago

power generated on a power meter is by no means accurate measure for personal energy expenditure. Unless of course you are machine running at 100% efficiency. (The only 24% efficiency factor for humans is based on so many assumptions) Only real way to measure energy expenditure accurately is using breathing measurements. VCO2/VO2

iplaw 10y ago
A trained cyclist is roughly 25% efficient, and 1 kCal = 4.184 kJ. The power meter precisely measures kJ. The end result is a near 1:1 ratio between kCal burned and kJ measured. Sure, the power meter under reports total expenditure. For example, it doesn't exactly account for BMR, increased expenditure due to elevated heart and respiration rate, utilization of muscles in your arms and torso, etc. However, it is extremely accurate compared to the alternatives.