The number of calories a person needs per day depends on many factors including age, sex, height, weight, activity level, and health goals. While general recommendations provide a starting point, calculating your specific calorie needs can help ensure you maintain energy balance for optimal health.
What is a calorie?
A calorie is a unit of energy. Specifically, 1 calorie (kilocalorie or kcal) is the amount of energy needed to raise the temperature of 1 kilogram of water by 1°C. Food calories are actually kilocalories.
When we refer to calories regarding nutrition and weight loss, we are talking about kilocalories or the number of kilocalories in food. The key point is that calories measure the energy content in food.
The number of calories you need depends on how much energy your body uses. Energy is needed to fuel basic body functions like breathing, blood circulation, cell production, brain function, digestion, and physical activity. The number of calories you need is highly individualized and depends on your age, sex, height, weight, activity level, and health status.
What are macro and micronutrients?
The calories in food come from three macronutrients:
- Carbohydrates – 4 calories per gram
- Protein – 4 calories per gram
- Fat – 9 calories per gram
Food also provides micronutrients including vitamins, minerals, phytochemicals, antioxidants, and fiber. Unlike macros, micronutrients do not provide calories or energy. Instead, they support many essential body functions.
Getting the right balance of macro and micronutrients ensures your body has both the energy and essentials needed for good health.
What is energy balance?
Your energy balance determines whether you maintain, gain, or lose weight. It refers to the relationship between the number of calories you consume (through foods and beverages) and the number of calories you burn (through basic body functions and physical activity):
- Positive energy balance – More calories consumed than burned leads to weight gain.
- Negative energy balance – More calories burned than consumed leads to weight loss.
- Energy balance – Equal calories consumed and burned maintains your current weight.
To achieve a healthy weight, aim for energy balance by adopting healthy eating habits and staying active. Monitoring your weight and adjusting your calories if needed helps sustain energy balance long-term.
Factors that determine calorie needs
Many interrelated factors affect how many calories you should consume each day, including:
Age
Calorie needs generally decrease gradually with age due to lowered metabolic rate and activity level. Estimated needs by age:
– Men
- 19-30 years: 2,400-2,600 calories/day
- 31-50 years: 2,200-2,400 calories/day
- 51+ years: 2,000-2,200 calories/day
– Women
- 19-30 years: 2,000-2,200 calories/day
- 31-50 years: 1,800-2,200 calories/day
- 51+ years: 1,600-2,000 calories/day
Sex
Males generally have higher calorie needs than females, mostly because of greater muscle mass and body size. Testosterone in men also increases muscle mass and energy expenditure.
Height and Weight
Larger individuals and those with more lean body mass need more calories than smaller people with less lean body mass. The body burns calories just maintaining bodily functions and lean mass.
Activity Level
People who engage in more physical activity need more calories than more sedentary people. Exercise, sports, work activity, and non-exercise activity all impact calorie needs. Active people can require 600-1,000+ more calories per day.
Health Status
Certain medical conditions and medications can affect calorie needs. Digestive disorders, diabetes, thyroid dysfunction, heart disease, and medications like steroids impact metabolic rate and calorie requirements.
Growth, Pregnancy & Breastfeeding
Rapid growth, pregnancy, and breastfeeding increase calorie needs. Teens, pregnant women, and new mothers require more calories to support development, fetal growth, and milk production.
Thermic Effect of Food
Digesting, absorbing, and metabolizing foods burns calories due to the thermic effect of food. Protein has the highest thermic effect (20-30% of calories burned), carbs are intermediate (5-10%), and fat the lowest (0-3%). High protein diets increase total calories burned.
General calorie recommendations
While calculating individual needs is ideal, general recommendations provide a starting point:
– Sedentary men: 2,200-2,400 calories/day
– Sedentary women: 1,600-2,000 calories/day
– Active men: Up to 3,000 calories/day
– Active women: Up to 2,400 calories/day
Within these ranges, a 500 calorie/day deficit promotes 1 pound per week weight loss, while a 250-500 calorie surplus supports muscle gain. Monitor your weight and adjust calories gradually as needed.
Calculating your calorie needs
While general guidelines are helpful, several methods allow you to calculate your approximate calorie requirements more precisely:
Calorie Calculator
Online calorie calculators allow you to input personal details like age, sex, height, weight, and activity level to estimate calorie requirements. Calculators consider the various factors that influence needs.
Calories Burned Calculator
Use calculators estimating the calories you burn from your resting metabolic rate (RMR) plus daily activities. RMR is the energy needed for basic body functions, comprising 60-75% of calorie expenditure for sedentary people but dropping as activity increases.
Calorie Counting Apps
Apps like MyFitnessPal allow you to log your food intake and activities to tally your total calories consumed and burned each day. Tracking over time provides a tailored assessment of your needs.
Activity Trackers
Wearable devices like Fitbit track your activity 24/7. They provide data on calories burned from all activities, allowing you to adjust food intake accordingly.
Measured Energy Requirement (MER)
For clinical accuracy, your MER can be measured by indirect calorimetry. This involves determining oxygen consumption and carbon dioxide production from inhaled and exhaled breath to calculate calories burned.
Adjusting calories for goals
Once you know your maintenance calories for energy balance, you can adjust intake up or down to align with your health goals:
- Weight loss: Reduce calories by 250-1000 per day to lose 0.5-2 pounds per week.
- Muscle gain: Increase calories by 250-500 per day, focusing on sufficient protein intake.
- Athletic performance: Appropriately increase calories to fuel training and optimize recovery.
- Medical needs: Adjust calories on the advice of your healthcare professional to support health conditions.
Monitor progress and body weight and gradually adjust calories as needed over time to sustain goal progress.
Diet tips to help manage calories
To help manage your calories for health and wellbeing:
- Eat plenty of vegetables, fruits, and whole grains. They provide vitamins, minerals, fiber and volume with fewer calories.
- Choose lean proteins like fish, poultry, beans, lentils, and low-fat dairy for satiety.
- Limit high-calorie foods like sugars, refined grains, and saturated fats.
- Control portions and avoid oversized servings to manage calorie intake.
- Drink water instead of sugary drinks.
- Pay attention to condiments, dressings, oils and spreads that add extra calories.
- Stay active with both exercise and non-exercise activity for higher daily calorie burn.
Adopting healthy eating strategies tailored to your calorie target supports successful weight management.
The bottom line
How many calories you need varies based on age, sex, size, activity level, health status, and goals. While general recommendations provide a starting point, calculating your needs more precisely allows you to better meet your energy and health needs long-term.
Aim to balance the calories you consume with the calories you expend over time. Adjust your calorie intake up or down as needed to achieve energy balance or move toward your weight and health goals. Focus on a nutritious, portion-controlled diet and active lifestyle for calorie management success.
