Fitbit And Calories: Tracking Your Sleep Burn

Fitbit is a wireless-enabled fitness and calorie-tracking device that can be clipped onto the user's clothing. It uses an internal motion detector to track the wearer's movement, sleep, and calories burned. The device provides users with metrics such as the number of steps taken, calories burned, and the time it took the wearer to fall asleep. Interestingly, some users have noticed that their Fitbit records a significant number of calories burned even before they have gotten out of bed in the morning. This has sparked discussions about whether Fitbit tracks calories burned while sleeping and, if so, how it calculates these calories.

How does Fitbit track calories burned while sleeping?

Fitbit tracks calories burned while sleeping by utilizing a standard formula similar to 0.42 calories per pound per hour. This formula takes into account various factors such as age, gender, height, and weight to estimate the number of calories burned during sleep. For example, a person weighing 150 pounds will burn approximately 63 calories per hour.

The Fitbit tracker resets at midnight, so by 6:00 a.m., an individual can expect to have burned around 378 calories during sleep. This count appears on the tracker when an individual wakes up, reflecting their estimated calorie burn for the day so far, including the time spent sleeping.

It is important to note that Fitbit also tracks Basal Metabolic Rate (BMR) or the number of calories an individual's body burns just to stay alive. This contributes to the total calorie burn displayed on the tracker, even if the individual has not actively exercised or moved much.

While Fitbit provides valuable insights into calorie burn, it is not perfect and may occasionally display 'phantom' calorie spikes. These discrepancies can occur due to various factors, and it is always a good idea to consult other sources and tests to cross-reference the data.

Additionally, Fitbit offers a wireless base station or docking unit that can sync with the device when it comes within 10 feet. This allows users to transfer their data to Fitbit's online portal, which includes a dashboard for understanding activity levels, calories burned, and a database of foods with their estimated calories for more comprehensive tracking.

How accurate is the Fitbit tracker?

The accuracy of Fitbit trackers varies depending on several factors. A 2018 review of Fitbits found that accuracy varied according to factors such as where they were worn (with the torso being more accurate than the wrist), whether the wearer was walking uphill, and whether they were walking at a constant speed or stopping and starting.

Fitbit trackers are considered accurate when they reflect the normal amount of calories that a body uses while sleeping. They utilize a standard formula similar to 0.42 calories per pound per hour. For example, a person weighing 150 pounds will burn approximately 63 calories per hour. The count resets at midnight, so by 6:00 a.m., it would amount to 378 calories. This is considered an accurate reflection of the user's BMR (basal metabolic rate) calories.

However, a 2020 study that examined a variety of gadgets from Apple, Garmin, Polar, and Fitbit found that all the devices were inaccurate more often than they were accurate. The Fitbit Classic, for instance, tended to underestimate calorie burn, while the Fitbit Charge usually overestimated it. A more recent study, published in 2022, compared the Apple Watch 6, the Fitbit Sense, and the Polar Vantage V. The researchers had volunteers wear all three gadgets while engaging in various activities, and every gadget, for every activity, was judged to have "poor accuracy," with coefficients of variation ranging from 15% to 30%.

Fitbit trackers use a 3-axis accelerometer to count steps and determine the frequency, duration, intensity, and patterns of movement. They can also use GPS data to calculate distance travelled. Additionally, they can measure heart rate, which is a key factor in determining smarter sleep stages. While these features provide a wealth of data, the accuracy of Fitbit trackers, especially for calorie burn, remains a subject of debate.

How does Fitbit's calorie tracking compare to other trackers?

Fitbit's calorie tracking feature is designed to provide insights into your daily activity levels and calorie expenditure. It uses an internal motion detector to track your movements and estimate calorie burn throughout the day and night. While this data can be useful for comparing your activity levels over time, it's important to recognise that it may not always be perfectly accurate.

The accuracy of Fitbit's calorie tracking has been the subject of several studies and user discussions. One study from 2017 found that the Fitbit Surge had a median error of 27% in counting calories burned, which was considered one of the better performances among the devices tested, including the Apple Watch, Basis Peak, Microsoft Band, and Samsung Gear S2. A more recent study in 2019, however, indicated that trackers may still be prone to overestimation. Researchers from Aberystwyth University found that a Fitbit Charge 2 overestimated calorie burn from a walk by 53.5%.

It's worth noting that the accuracy of calorie tracking can be influenced by various factors. For example, the Fitbit device relies on motion detection and may not capture all aspects that impact calorie burn, such as body fat percentage, body temperature, and blood sugar levels. Additionally, individual variations in metabolism, health, and activity levels can further affect the accuracy of calorie estimates.

When comparing Fitbit's calorie tracking to other trackers, it's important to recognise that no method is perfectly accurate. All tracking devices and methods, including pen-and-paper food journals, have their limitations and inaccuracies. However, Fitbit's calorie data can still be valuable for relative comparisons of your own activity levels and calorie expenditure over time.

To improve the accuracy of calorie tracking, it is recommended to ensure a snug fit for the device, as good contact with the skin can enhance the reliability of the data collected. Additionally, combining Fitbit's calorie tracking with its other features, such as heart rate monitoring and sleep tracking, can provide a more comprehensive understanding of your overall health and fitness.

How does Fitbit's calorie tracking work with the user's diet?

Fitbit's calorie tracking works by using an internal motion detector to track the wearer's movement, sleep and calorie burn during both the day and night. The Fitbit app allows users to log their food intake each day to see how many calories they eat versus their estimated calories burned. The Fitbit app also allows users to set a weight-loss goal, which determines the user's daily calorie deficit target based on the level of intensity they choose for their food plan. The Fitbit tracker counts the user's daily step count and may determine hours of sleep, which is then synced to the Fitbit website.

The Fitbit tracker uses an accelerometer and other sensors to estimate the user's daily calories burned, while the Fitbit weight scale can automate weight tracking. The Fitbit app also includes a database of foods and their estimated calories, so users can track their calorie intake versus burn. The Fitbit tracker also estimates the user's BMR (basal metabolic rate), which is the number of calories the body uses while sleeping. This is calculated using a standard formula similar to 0.42 calories per pound per hour. For example, a person weighing 150 pounds will burn approximately 63 calories per hour while asleep.

The Fitbit app allows users to set a custom heart rate zone, which can be used to determine the intensity of workouts. The app also includes a meal plan feature, which can be used to help users achieve and maintain their weight goals. The Fitbit tracker can also be linked to other apps, such as MyNetDiary, which can keep track of the user's food intake and estimate their activity calories based on activity type and duration. By linking MyNetDiary with Fitbit, users can see the actual balance of the calories they burn and eat during the day, which can help them lose weight faster and smarter.

How does Fitbit's calorie tracking work with the user's exercise routine?

Fitbit devices track a user's calorie burn during both the day and night. They do this by using an internal motion detector to track the wearer's movement, sleep, and calorie burn. The Fitbit tracker estimates your calorie burn based on your age, gender, height, and weight.

The Fitbit tracker also takes into account your Basal Metabolic Rate (BMR), which is the number of calories your body burns while at rest to maintain vital bodily functions. This means that even if you haven't moved, you are still burning calories. The number of calories burned while sleeping will vary from person to person, but a standard formula of 0.42 calories per pound per hour is used to calculate this. For example, a person weighing 150 pounds will burn approximately 63 calories per hour while asleep.

The Fitbit tracker also allows users to log their food intake, and it has a database of foods and their estimated calories. This allows users to track their calorie intake versus the number of calories burned. The tracker will show the number of calories burned from activity during the night, which may result in higher-than-expected calorie burn rates for those who move a lot in their sleep.

The Fitbit tracker is, therefore, a useful tool for those seeking to understand their calorie intake and burn in relation to their exercise routine. By tracking the number of calories burned both during sleep and while active, users can get a more accurate picture of their overall calorie expenditure and adjust their exercise routine accordingly.

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