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I wish they'd get rid of "calories" it's irrelevant.

The continued emphasis on “calories” is not only outdated but fundamentally misleading. Caloric measurement is an oversimplified and reductionist approach to health and nutrition. It fails to reflect the complex regulatory systems of human metabolism, individual differences in energy expenditure, and the profoundly different metabolic effects of macronutrients.

The notion that “a calorie is a calorie” ignores the fact that carbohydrates, fats, and proteins are metabolized through distinct biochemical pathways and exert different hormonal effects—particularly on insulin, satiety, and fat storage. For example, 100 calories of sugar is not metabolically equivalent to 100 calories of protein or fat.

If you’re trying to lose weight, reducing refined carbohydrates and emphasizing protein and healthy fats—while eating to satiety—tends to be far more effective than simply slashing calories. This approach aligns better with how the body actually regulates hunger, energy balance, and fat storage.

It’s time to move beyond the calorie and toward a more nuanced, biologically informed understanding of nutrition.

What you are saying is definitely true, but it's almost impossible to have a consistent metric (that works as a good approximation of energy taken in and burned) to track your diet with nutrition make up, especially for weight loss, at least currently. Both food labeling and sensor tech need to evolve to make this work. As it is right now, calories count is still the best way to numerically track for weight loss, despite its simplifications and deficiencies.
 
My watch seems consistent measuring activities day to day, so it at least seems helpful to let me know if I burned as many calories as the day before.

Seems wildly inconsistent between me and my wife. We can go on a hike together and my watch shows 800 calories burned where hers shows 400. Maybe the fact the she’s half my weigh accounts for the difference, but still seems like a wide discrepancy.
I do wonder how much self reported stats factor in.
 
These numbers mean nothing without showing other devices’ error rates.
 
What you are saying is definitely true, but it's almost impossible to have a consistent metric (that works as a good approximation of energy taken in and burned) to track your diet with nutrition make up, especially for weight loss, at least currently. Both food labeling and sensor tech need to evolve to make this work. As it is right now, calories count is still the best way to numerically track for weight loss, despite its simplifications and deficiencies.
Wait until we tell people that the standard error rate for counting calories is about 30%.
 
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The Apple Watch tells me I burn over 800 calories in an hour of tennis. No way, not believable; that amount of calories burnt in an hour would help! (In addition to avoiding the pizza).
Depending on your body weight and intensity, 800 is not completely out of the question. Most sources say that an average hour of tennis should burn about 600 to 700 calories for a moderate intensity tennis session.
 
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These numbers mean nothing without showing other devices’ error rates.

Sure it does. It's comparing actual calories burned, in a controlled lab setting, against what the Apple Watch says, not against other devices.
 
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Maybe I'm "sitting wrong" but I hit my stand goal despite sitting for vast portions of the day and making no effort to stand either?! Last week I was sick and sleeping (laying down, as one does) all day. Yet I still reached my stand goal?! 😆 (Apple Watch 7 btw)
 
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Maybe I'm "sitting wrong" but I hit my stand goal despite sitting for vast portions of the day and making no effort to stand either?! Last week I was sick and sleeping (laying down, as one does) all day. Yet I still reached my stand goal?! 😆 (Apple Watch 7 btw)

Reminded me of this:

o6fr90qqlpx51.jpg
 
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I’ve had two Apple watches, including a brand new one… I can jump rope for an hour and the watch does not even notice that I am exercising.
Ridiculously bad.
The funny thing is, they sell more watches than anybody else, even though all this health and measurement stuff doesn’t work.
 
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Interesting to know about this. Hopefully Apple will be able to do something to improve the readings.
 
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I hadn't heard that and I've ran marathons. You referring to VO2 Max?

Garmin shows it as 45 and Apple shows 40.8. I don't pay any attention to the number and they both show above average, but it's interesting how different it is.
VO2 Max is very bad on Apple Watch and varies wildly. It errs on the low side significantly, when it's accurate at all.
 
I’ve had two Apple watches, including a brand new one… I can jump rope for an hour and the watch does not even notice that I am exercising.
Ridiculously bad.
The funny thing is, they sell more watches than anybody else, even though all this health and measurement stuff doesn’t work.
I would play baseball for 2 hours and it would report barely any exercise at all despite my heart rate elevated most of the time from non-stop running. Turn on an open workout and magically it starts recording all the metrics correctly.

They really need to get it to the point where it can measure that accurately all the time, without killing the battery.
 
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I would play baseball for 2 hours and it would report barely any exercise at all despite my heart rate elevated most of the time from non-stop running. Turn on an open workout and magically it starts recording all the metrics correctly.

They really need to get it to the point where it can measure that accurately all the time, without killing the battery.

When running, my watch doesn't record heart rate until a good 5-10 mins into the run. My 3 never had that problem, but it's always been an issue with my 6.

My new Garmin records without issue.
 
Ive been gaining weight since the Appleu Watch, whereas I had a Fitbit before and was shedding weight.
 
I guess I'm not burning 900 calories a day largely sitting at my desk? :) Probably what confuses Apple Watch is me constantly tapping or shaking my feet about (nervous disposition), or moving my arms around.
 
Every device like an Apple Watch is great for showing you trends. It can let you know when you are trending up or down. But the absolute numbers have to be taken with a grain of salt.

Here is an example. If I do a treadmill workout without hitting the workout button, the Apple Watch says I expend 100 cals. If I do the same workout but hit the workout button, it says I expend 350 cals. Why?

But it’s a can’t beat device for being aware of trends.
 
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I'm not worried about the accuracy compared to an actual calorie burned. i need consistency so I can be certain I'm consistent or improving or getting worse on my level of effort for various activities. I also want consistency between various activities on measuring level of effort. They can call them Apple energy units for all i care as long as they are consistently measured. Regularly stepping on the scale will tell me what I need to know about my calorie intake to burn ratio.
 
Body size is a huge factor. You cannot compare two people.
To expand and clarify a little for others who are not making the inference from what was written: "You cannot compare two people without factoring in body size, sex, body fat, lean muscle composition, bone density, basal metabolic rate, and more."

Body size (weight and height are major factors) is a great rough start to estimate calories burned at rest and in activities. Here's one way to estimate your basal metabolic rate (BMR):

Females: (10*weight [kg]) + (6.25*height [cm]) – (5*age [years]) – 161
Males: (10*weight [kg]) + (6.25*height [cm]) – (5*age [years]) + 5

To estimate total calories including daily activity, you can multiply by a scale factor based on an estimated activity level:
  • Sedentary *1.2
  • Lightly active *1.375
  • Moderately active *1.55
  • Active *1.725
  • Very active *1.9
This is why calories burned in a day can vary drastically between people.

For example, a 50 year old female who is 160 cm tall and 72.6 kg has a resting rate of about 1578 kcal/day.
A 50 year old male who is also 160 cm tall and 72.6 kg has a resting rate of about 1777 kcal/day.

Same age, height, and weight but differences in BMR. This is largely driven by estimates of typical female/male differences in lean muscle mass and body fat.

Similarly, calories burned while exercising will also differ.

I don't know what formula the Apple Watch / Health app uses, but it's something like that. The AW algorithms to estimate calories burned are clearly (as shown in the article), not perfectly accurate. They are good enough, however, to get an overall sense of activity for an individual over time.
 
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The calories burned on the Apple Watch is very inconsistent for me. Every morning for my morning walk, I walk the same path, duration, avg heart rate, and pace. Yet the active calories recorded for these workout session ranges from 300 to 400.

I'm not sure which other metrics Apple use to calculate calories.
Let's assume you used 350 Kcal on the walk. This means the error was 50. 50/350 is only a 14% error. So your watch is VERY good and about twice as accurate as the study this article is referring to. 14% is acceptable for consummer-level fitness trcking.

OK, the above assumes the watch's errors are random and not biased. We don't know this. But the point of tracking is not to know exactly what you did today, but to track trends over time. For example an unfit person might not be able to burn many calories because they cannot walk fast and have to quit soon. But after a year, he might be up to walking briskly for hours. The idea of tracking is you want to see a general trend of MORE calories burned this month than last month. 14% accuracy is more than good enough for that purpose.

Even with a 28% error, if it is random, the "calories burned per month" number should be nearly dead-on.
 
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I just paid(!) to get access to the paper.

* It's a meta-study, so all they do is to read other papers and make a conclusion of it
* Most papers they look at are very old
* Because most papers they look at are very old, the most common model used in the studies is Apple Watch Series 1 LOL

I don't know about you, but I'm sure my Series 10 is better than the Series 1 in every single regard.
 
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Some of what you wrote isn't true. It's also harmful from a dietary perspective to say things like this: "You can bike for 100s of miles and watch the calories add up - but if you go home and eat some pizza - you've wasted your entire day."

That induces guilt over what people eat and can lead to eating disorders (that really happens). Exercise is not a waste, just because you eat pizza afterward. The exercise has benefits for health despite what we eat. Over-focus on calories can also be problematic, but take this as an opportunity to learn about the benefits of exercise regardless of our diet.

If you expend more calories than you consume, you will not gain weight (there is a little fuzziness around the edges of that). In other words and to be more precise, from a strictly caloric perspective, gaining adipose tissue while consistently expending more calories than consumed is virtually impossible due to the laws of thermodynamics. Biology is complex due to hormones, water retention, inflammation, and other processes, but the overarching laws of thermodynamics hold true for us.

For example, if I burned 500 calories in a workout and then ate 300 calories of pizza, I would not gain weight. If I burned 500 calories in a workout and then ate 300 calories of broccoli, I would not gain weight.

Or, if my total caloric expenditure in a day was 2,200 and my total caloric intake was from pizza, sugary cereal, a hamburger, and one lettuce leaf drenched in ranch dressing but was only a total of 2,100, I would not gain weight. I could develop some health conditions, but the exercise and caloric 'restriction' would counteract some, even much of them.

This doesn't mean pizza and broccoli are equally healthy, which is part of your point, but "calories out" >= "calories in" and exercise are associated with many health benefits, including longevity and quality of life, above and beyond the food we eat.

Again, food matters, it just matters less than calories from an overall weight and health perspective. This is important to know because it can help prevent weight gain. Weight loss is notoriously difficult. Preventing weight gain takes work as well, but is relatively easier. A simple focus on keeping calories in <= calories out over time will prevent weight gain*.

It's easier to "obsess" over total calories than to "obsess" over what foods you are eating. My encouragement to my students when we cover this in one of my classes where we cover health, is to focus first on general activity and exercise and sleep (if you sleep less, you tend to eat more!) for health reasons, then focus on keeping "calories out" >= "calories in", then focus on the 'quality' of food.

Prevention is much preferred over intervention. But if there needs to be intervention, the best diet is one you will eat and keep. That usually means keep what you are eating, just eat a little less of it. Rather than switch from pizza to kale and goat cheese, eat 2 slices of pizza instead of 3. Then gradually you can build in 'healthier' foods.

*There are some medical conditions and other issues that complicate the picture, but the general principle is true.
The current system to assess the calories in food measures the total energy stored in a food, ie the maximum calories that the body may absorb. But our metabolism is more efficient in extracting calories from, say, sugars (basically 100%), than it is from raw vegetables. Remember that your digested food still contains energy / calories (it can burn); which means the body does not absorb all the calories of every food.
 
The current system to assess the calories in food measures the total energy stored in a food, ie the maximum calories that the body may absorb. But our metabolism is more efficient in extracting calories from, say, sugars (basically 100%), than it is from raw vegetables. Remember that your digested food still contains energy / calories (it can burn); which means the body does not absorb all the calories of every food.

It also has to do with your gut flora. Microbes help break down foods, so therefor some can extract more calories out of certain types of food vs. others.

It's one of the reasons that a microbiome transplant from a chronically overweight person, to a ideal weight person, can cause them to become overweight, even with no change in diet or exercise.
 
Sure it does. It's comparing actual calories burned, in a controlled lab setting, against what the Apple Watch says, not against other devices.
I disagree, we can't live in a lab. We need to know which devices are going to give us the best estimate.
 
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