Consider your energy needs as a bank account. When you consume calories, you make deposits, and when your body expends energy on activities, you make withdrawals. Nutritionists categorize your daily energy withdrawals into two parts:

• The energy required when your body is at rest.
• The energy needed for your daily activities.

To maintain equilibrium in your energy account, ensure that your daily intake is sufficient to offset your withdrawals. 

Generally, infants and adolescents burn more energy per pound than adults, as they constantly generate significant amounts of new tissue. Similarly, the average man expends more energy than the average woman due to the larger size and greater muscle mass of his body. 

Related: How to Count Calories in Food

Resting energy expenditure (REE)

Even during periods of rest, your body remains active. Your heart beats, your lungs undergo expansion and contraction, your intestines digest food, your liver processes nutrients, and your glands release hormones. Muscles often experience gentle flexing, and cells transmit electrical impulses among themselves. Meanwhile, your brain consistently communicates messages to every tissue and organ in your body.

How Many Calories Do You Need When You’re Resting

Resting Energy Expenditure (REE), also known as basal metabolism, is the energy your body utilizes during periods of rest to perform essential functions such as heartbeat, lung function, digestion, nutrient processing, hormone secretion, muscle activity, and cellular communication. REE constitutes 60 to 70 percent of your daily energy requirements.

To calculate your Resting Energy Expenditure (REE), begin by determining your weight in kilograms (kg). Since one kilogram equals 2.2 pounds, divide your weight in pounds by 2.2. For instance, if you weigh 150 pounds, this equates to 68.2 kilograms (150 ÷ 2.2). Input this value into the relevant equation provided in Table 1, and you’ll obtain your REE.

Understanding this information is valuable both for appreciating the scientific basis behind the fundamental calorie needs for survival and for pragmatically using it as a foundation to construct a practical, daily nutritional menu.

Gender and Age	Equation to Figure Out Your REE
Males
18–30	(15.3 x weight in kg) + 679
31–60	(11.6 x weight in kg) + 879
61 and older	(13.5 x weight in kg) + 487
Females
18–30	(14.7 x weight in kg) + 496
31–60	(8.7 x weight in kg) + 829
61 and older	(10.5 x weight in kg) + 596

Energy for work

After the Resting Energy Expenditure (REE), the second most significant portion of your energy expenditure is dedicated to physical activities—ranging from simple tasks like morning tooth brushing to more strenuous activities like gardening or working out in the gym.

Your total daily energy requirement, representing the number of calories you need, is the sum of your REE and the calories necessary to support your physical activities.

It’s natural to wonder if contemplating this information consumes energy. Surprisingly, not as much as one might think. For instance, to solve a crossword puzzle or write a chapter of a book, the average brain utilizes approximately 1 calorie every four minutes—only one-third of the energy required to keep a 60-watt bulb illuminated for the same duration.

Refer to Table 2 for the energy levels associated with various activities, ranging from the least energetic (sleep) to the most (playing football, digging ditches). Table 3 provides a personalized breakdown of these energy expenditure figures. 

Activity Level	Activity
Resting	Sleeping, reclining
Very light	Seated and standing activities, painting, driving, laboratory work, typing, sewing, ironing, cooking, playing cards, and playing a musical instrument
Light	Walking on a level surface at 2.5 to 3 mph, garage work, electrical trades, carpentry, restaurant trades, housecleaning, child-care, golfing, sailing, and table tennis
Moderate	Walking 3.5 to 4 mph, weeding and hoeing, carrying a load, cycling, skiing, tennis, and dancing
Heavy	Walking with a load uphill, tree felling, heavy manual digging, basketball, climbing, football, and soccer
Exceptionally heavy	Professional athletic training

Activity Level	Calories Needed for This Work for One Hour
Very light	80–100
Light	110–160
Moderate	170–240
Heavy	250–350
Exceptionally heavy	350+

Calculating Your Daily Calorie Needs

Determining your daily calorie intake can be a challenging task. Fortunately, the Institute of Medicine, responsible for establishing Recommended Dietary Allowances (RDAs) for vitamins, minerals, and other nutrients, has compiled a list outlining the average daily calorie allowances for healthy individuals across all age groups, from infants to seniors maintaining a healthful weight. These allowances are tailored to the level of daily physical activity.

Table 4 presents the calorie recommendations as estimated by the U.S. Department of Agriculture and Health and Human Services.

It’s important to note that in this context, “sedentary” reflects a lifestyle characterized by minimal physical activity associated with daily living. “Moderately active” denotes a lifestyle that incorporates physical activity equivalent to a daily 1.5-to-3-mile walk at a speed of 3 to 4 miles per hour, while “active” involves physical activity equivalent to walking 3 miles a day at the same pace.

Gender	Age (years)	Sedentary	Moderately Active	Active
Child	2–3	1,000	1,000-1,400	1,000-1,400
Female	4–8	1,200	1,400–1,600	1,400–1,600
	9–13	1,600	1,600–2,000	1,800–2,200
	14–18	1,800	2,000	2,400
	19–30	2,000	2,000–2,200	2,400
	31–50	1,800	2,000	2,200
	51–60	1,600	1,800
Male	4–8	1,400	1,400–1,600	1,600–2,000
	9–13	1,800	1,800–2,200	2,000–2,600
	14–18	2,200	2,400–2,800	2,800–3,200
	19–30	2,400	2,600–2,800	3,000
	31–50	2,200	2,400–2,600	2,800–3,000
	51–60	2,200	2,200–2,400	2,400–2,800
	61–65	2,000	2,400	2,800
	66–75	2,000	2,200	2,600
	76+	2,000	2,200	2,400

Summary

Calories are your friends, providing the energy for a healthy life. The key is to take control of your calories instead of letting them control you. Understanding which foods give you energy allows you to plan your intake based on your activity level. When you do this, your body appreciates it every day.

Reference: Rinzler, C. A. (2021). Nutrition for dummies. Hoboken, NJ: John Wiley & Sons, inc.