An elevated heart rate due to anxiety or stress, such as during an interview, can indeed lead to an increase in calorie burning, but it may not be significant enough to have a substantial impact on your overall calorie expenditure.
When you experience anxiety or stress, your body's fight-or-flight response is activated, which leads to the release of stress hormones like adrenaline and cortisol. These hormones increase your heart rate, respiratory rate, and metabolic rate. The increased metabolic rate means your body is using more energy (calories) to cope with the stressor.
While you are burning some extra calories during this period, the actual amount may not be very significant, especially if the anxiety is short-lived, like during an interview. The impact on your overall daily calorie expenditure is likely to be minimal.
Fitbit and similar fitness trackers estimate calorie burn based on various factors, including heart rate data and activity level. When your heart rate is elevated due to anxiety, your Fitbit may interpret it as increased physical activity and thus estimate a higher calorie burn than usual.
It's important to remember that the calorie burn estimates provided by fitness trackers are just that—estimates. They are not always 100% accurate and can vary based on individual factors and the specific device's algorithms.
In summary, experiencing an elevated heart rate due to anxiety during an interview may lead to some extra calorie burn, but it is unlikely to have a significant impact on your overall daily caloric expenditure. The primary focus should be on managing stress and anxiety for your overall well-being rather than relying on calorie burn during such situations.