The question of whether to subtract exercise calories from your daily food intake is a common point of confusion when managing weight. This dilemma centers on the concept of energy balance—the relationship between the calories consumed and the calories expended. To achieve weight loss, a person must maintain a consistent calorie deficit, meaning they expend more energy than they take in. Calculating this deficit accurately requires understanding all the ways the body uses energy.
Understanding Total Daily Energy Expenditure
Your body burns calories constantly, not just during dedicated workouts, and this total amount is called your Total Daily Energy Expenditure (TDEE). The TDEE represents the total number of calories your body burns over a 24-hour period to maintain all bodily functions and activities. This expenditure is the sum of three main components that determine your baseline caloric needs.
The largest component is the Basal Metabolic Rate (BMR), which accounts for 60 to 75 percent of your TDEE. BMR is the energy required to keep your body functioning at rest, supporting processes like breathing, circulation, and cell production. A smaller portion, about 10 percent, is the Thermic Effect of Food (TEF), which is the energy spent digesting and absorbing nutrients from the food you eat.
The remaining energy expenditure comes from physical activity, divided into structured exercise and Non-Exercise Activity Thermogenesis (NEAT). NEAT covers spontaneous movement like fidgeting or walking. Most initial calorie targets are set by estimating TDEE using an activity multiplier that accounts for a general level of daily activity.
Why Exercise Calorie Estimates Are Flawed
Simply subtracting the calorie count displayed on a treadmill or a wrist-worn device can undermine your efforts because these estimates carry a large margin of error. Consumer-grade fitness trackers and gym equipment rely on generalized algorithms to estimate energy expenditure. These algorithms use basic physiological data, such as your age, height, weight, and heart rate, to make a broad prediction.
The major limitation is that these devices cannot measure your body’s true metabolic rate, which requires specialized laboratory equipment to measure oxygen consumption. Research has shown that the inaccuracy in these wearable devices can be substantial, with some studies reporting error margins for calorie tracking ranging from 27% to over 90% in certain models. This wide variability means that if a device claims a 400-calorie burn, the actual expenditure could be significantly lower.
The devices fail to account for individual metabolic efficiency, body composition, and exercise form, all of which influence true calorie burn. Relying on an inflated number risks overeating and erasing the calorie deficit needed for weight management. Treating the reported exercise calories as a strict allowance for extra food often leads to stalled progress.
The Recommended Strategy for Net Calories
A more effective strategy is to manage net calories by creating a deficit in your initial TDEE calculation, rather than chasing inaccurate exercise numbers. The most reliable method is to calculate your TDEE based on your general activity level, including planned exercise, and then set your calorie goal 300 to 500 calories below that number. This approach establishes a consistent deficit without needing to manually adjust for every workout.
This strategy treats the exercise session as an integral part of your energy expenditure, not a bonus that must be “eaten back.” Using a consistent calorie target ensures you maintain an average deficit over the week, which drives weight change. This method also creates a buffer, protecting your deficit from the inaccuracies of fitness tracker reporting.
If you prefer to track exercise calories separately, a cautious approach is to only consume a portion of the estimated calories burned, perhaps 50 percent, especially if your goal is weight loss. This partial adjustment provides extra energy for recovery while acknowledging the high probability of device overestimation. The most actionable focus should be on monitoring actual results, such as weekly weight changes, and adjusting your food intake based on that progress, not solely on a tracker’s daily calorie readout.