Apple Watch: Tracking Calories Burned During Sleep

The Apple Watch is a smart device that can track several health metrics, including calories burned. While there are conflicting reports about its accuracy, the watch does provide estimates of calories burned while sleeping. Users have reported varying calorie burn readings, with some questioning the accuracy of the data. However, Apple states that the watch uses personal information such as height, weight, gender, and age to calculate calorie burn, which may explain the discrepancies. To access this data, users can utilize the Activity app on their watch or the Health app on their iPhone.

Calories burned while sleeping

The Apple Watch does track calories burned while its wearer is sleeping. The watch's built-in Activity app shows the user their active calories burned under the Move goal. The total calories burned can be viewed on the Fitness app on the user's iPhone. This number includes both active and passive calories. Active calories are those burned from movement, while passive calories are the set amount of calories the user's metabolism burns while at rest.

The Apple Watch uses personal information such as height, weight, gender, and age to calculate the number of calories burned. However, some users have reported inconsistencies in the data. For example, one user reported that their Apple Watch recorded them as burning 600 calories during sleep, which seemed high. Another user reported that their watch recorded them as burning 287 active calories during sleep, despite the user being asleep for three hours.

It is worth noting that the Apple Watch may not accurately track sleep and calories burned during sleep when the user sleeps past the scheduled sleep time. Additionally, some users have reported issues with the watchOS update, which has affected the accuracy of calorie tracking during sleep.

Active vs passive calories

The Apple Watch does track calories burned while sleeping. However, it is important to distinguish between active and passive calories to understand the data provided by the watch.

Active Calories

Active calories refer to the additional calories burned through physical activity or exercise beyond what would be burned at rest. These are the calories burned during activities such as walking, climbing, or jogging. The Apple Watch uses sensors like the heart rate monitor to track active calories. Active calories are calculated by subtracting the Basal Metabolic Rate (BMR) from the total calories burned. BMR is the baseline of calories burned per hour and is predicted using mathematical formulas that consider an individual's height, weight, gender, and age.

Passive Calories

Passive calories, also known as resting calories, are the calories burned by the body to maintain essential functions while at rest. These include the calories expended by the body to sustain vital processes even when an individual is lounging or sleeping. The Apple Watch calculates passive calories based on personal information such as height, weight, gender, and age, independent of physical activity or heart rate.

The distinction between active and passive calories is crucial for understanding the total calories burned. Total calories include both active and passive calories. While active calories focus on the additional energy expenditure during exercise, passive calories represent the baseline metabolic rate required to sustain life. By separating these metrics, the Apple Watch provides a more comprehensive understanding of energy expenditure, helping users make informed decisions about their activity levels and calorie consumption.

Accuracy of Apple Watch

The accuracy of Apple Watch's calorie tracking has been a topic of discussion among users, with some reporting inconsistencies and others finding it reliable for weight loss regimens. While it is challenging to precisely determine calorie burn, the Apple Watch is considered one of the best devices for this purpose due to its heart rate tracking capabilities.

To enhance the accuracy of the Apple Watch's calorie calculations, it is crucial to ensure correct settings. This includes updating personal information such as height, weight, gender, and age in the Health app. Additionally, recalibrating the watch and wearing it correctly are important factors. The watch's motion and distance tracking should also be calibrated for improved precision.

Some users have questioned the accuracy of the Apple Watch's calorie tracking while sleeping. One user reported that their watch tracked approximately 78kcal burned per hour while sleeping, even when not worn. Another user, who wore their watch during sleep, found that it recorded significantly higher calories burned (600) compared to their typical non-exercise days. These discrepancies highlight the complexities of accurately measuring calorie burn during sleep.

A 12-week study conducted by an individual in 2019 aimed to assess the accuracy of the Apple Watch's calorie tracking. The participant rigorously tracked their diet and exercise while wearing the watch for 22 hours daily. They found the Apple Watch's energy expenditure calculations surprisingly good, concluding that it could be used as part of a weight loss regimen. However, they acknowledged the limitations of a single-person study and the potential for individual variations in results.

While the Apple Watch provides reasonably accurate calorie tracking, it may not perfectly detect specific activities. Selecting a workout type on the watch helps it differentiate between activities like walking, treadmill use, or running, improving the accuracy of its calorie calculations for those activities. Overall, the Apple Watch offers a convenient way to track calories burned, although some degree of discrepancy is expected, as observed with other fitness trackers.

Comparison to Fitbit

The Apple Watch and Fitbit are two of the most popular smartwatches on the market, with both offering a range of health and fitness tracking features. While the Apple Watch has long been established as a fitness tracker, Fitbit has been cornering the market for fitness and sleep tracking for years.

The Apple Watch uses motion and heart rate data to determine calorie count, which then dictates the Move metric of the Activity app. The watch will also use your personal information, such as height, weight, gender, and age to calculate how many calories you burn. However, the Apple Watch has to be charged overnight, which means it misses out on tracking the calories burned while you sleep.

Fitbit, on the other hand, estimates the number of calories burned based on your BMR (Basal Metabolic Rate), which is calculated using your height, weight, age, and gender. The Fitbit also takes heart rate into account for a more detailed estimate. Fitbit's sleep tracking algorithm is highly regarded, and it can track sleep stages and cycles, giving you a comprehensive view of your sleep. The Fitbit also has a longer battery life, which can last a week or more between charges, so you can wear it overnight without worrying about it dying.

The Apple Watch OS 9 update has improved the watch's sleep tracking capabilities, adding a Sleep app that helps you establish a regular bedtime routine and keep track of your sleep trends. It also added Sleep Stages, which monitor stages like REM and deep sleep. However, some users have reported issues with the watch not accurately recording their sleep data or calories burned after installing the OS 9 update.

In terms of design, the Apple Watch is bulkier and may be uncomfortable to wear in bed, especially if you have petite wrists. The Fitbit, on the other hand, is sleek and minimal, with a narrow profile that is less noticeable on the wrist.

Both devices offer unique features and capabilities, and the best choice for you will depend on your specific needs and preferences. If you are an iPhone user with a higher budget, the Apple Watch may be a good option, especially if you are already integrated into the Apple ecosystem. If you are looking for a more affordable, minimalistic, and compatible device, the Fitbit might be the better choice.

Calorie data on iPhone

The Apple Watch can track your sleep stages and the amount of sleep you get each night. However, it does not track calories burned while you are sleeping. The Apple Watch does track your active and passive calories burned throughout the day. Active calories refer to the calories burned through movement, while passive calories are the calories burned by your metabolism while at rest.

To view your calorie data, you can use the Fitness app on your iPhone. Open the app and tap the Activity rings at the top. Your total calories burned for the day will be displayed on the bottom left of your screen. To view data for another day, you can select a different day from the top of the screen or tap the calendar icon on the top right.

The passive calories burned can be calculated by subtracting the active calories ("Move" goal) from the total calories. This value represents your base metabolic rate.

It is important to note that the Apple Watch may not always provide accurate readings for calorie burn. Some users have reported inconsistencies in the data, especially after updating their watchOS. In such cases, you may need to manually add or adjust the data.

Frequently asked questions