How many calories do u burn a day
Pro Research Analysisby 
Searched over 200M research papers
Daily Caloric Expenditure: Understanding How Many Calories You Burn a Day
Basal Metabolic Rate (BMR) and Surface Area
One of the primary factors determining daily caloric expenditure is the Basal Metabolic Rate (BMR), which is the number of calories your body needs to maintain basic physiological functions at rest. Research indicates that heat production, and thus calorie expenditure, is proportional to body surface area. On average, the heat production per square meter of body surface is about 830 calories per day when muscular activity is excluded6. This foundational understanding helps in estimating the baseline caloric needs of an individual.
Human Metabolic Rate Compared to Other Primates
Humans have a significantly higher metabolic rate compared to other primates. Studies show that humans burn calories 27% faster than chimpanzees and other apes. This higher metabolic rate is essential for supporting our energy-demanding brain functions and maintaining larger brain sizes. Additionally, humans have more fat reserves, which provide energy during periods of food scarcity2.
Caloric Needs for Weight Loss
To lose weight, creating a calorie deficit is crucial. This can be achieved by either reducing caloric intake or increasing physical activity. Generally, a reduction of 500 to 700 calories per day is recommended to lose approximately 0.5 to 1 kilogram per week. Incorporating physical activity can accelerate this process, helping individuals reach their weight-loss goals more efficiently1.
Caloric Requirements in Special Conditions
Burn Patients
For individuals with burns, caloric needs can be significantly higher due to the hypermetabolic state induced by burn injuries. The caloric requirements for burn patients can be calculated using specific formulas that take into account the total body surface area (TBSA) affected. For instance, one formula suggests that the daily calorie input should be 1000 calories per square meter of body surface area plus an additional 25 calories per percent of TBSA burned3. Another study supports this by using the Curreri formula, which calculates caloric needs as 25 calories per kilogram of body weight plus 40 calories per percent of BSA burned5.
Conclusion
Daily caloric expenditure varies widely based on several factors, including basal metabolic rate, physical activity, and specific conditions such as burn injuries. Understanding these factors can help individuals better estimate their daily caloric needs and make informed decisions about diet and exercise to achieve their health and fitness goals.
Sources and full results
Most relevant research papers on this topic
Preserving Muscle Mass during Your Weight Loss Journey
Creating a calorie deficit by eating fewer calories or increasing physical activity can help maintain muscle mass while losing weight.
Estimation of the calorie requirements of burned Chinese adults.
Burned Chinese adults require a daily calorie intake of 1000 x m2 + 25 x per cent TBSA, with glucose providing 55-60 per cent of the calories, fat 20-30 per cent, and protein 15-20 per cent.
Observational StudyThe Demand for Food and Calories
Caloric consumption in rural Maharashtra, India, has a 0.3-0.5 elasticity with total expenditure, suggesting income is not constrained by nutrition.
Highly CitedThe importance of burn wound size in determining the optimal calorie:nitrogen ratio.
Burn patients with open wounds of less than 10% BSA may benefit from a 150:1 calorie:nitrogen ratio, while those with greater than 10% BSA open wounds require a 100:1 ratio to maintain positive nitrogen balance.
Non-RCTFIFTH PAPER THE MEASUREMENT OF THE SURFACE AREA OF MAN
Rubner's law may be re-examined, as it is clear that heat production in humans is proportional to surface area, with the average heat production per square meter being about 830 calories per day.
Highly CitedImperfect information on physical activity and caloric intake☆
Overestimating physical activity levels by one standard deviation leads to 40-60 extra calories per day, mainly from sugar and carbohydrate, and is strongest among less educated individuals and those with high variance in their activity levels.
Observational StudyCaloric Requirements in Burned Children: A Simple Formula to Estimate Daily Caloric Requirements
The surface area formula accurately estimates daily caloric requirements for burned children, with 40 patients gaining weight and 12 patients losing weight when following the recommended diet.
Observational StudySugars
Carbohydrates provide energy and prevent protein waste, while fats provide more calories per gram, but carbohydrates are equally efficient for providing energy and preventing protein waste.
Measured and predicted calorie requirements of adults during recovery from severe burn trauma.
2X predicted resting metabolic rate is the most accurate method for estimating caloric support during recovery from severe burn trauma, minimizing the risk of overfeeding.
Observational Study