Adults typically require between 1,600–3,000 calories per day. However, how many calories a person should eat in a day varies depending on a person’s sex, age, height, and lifestyle.
The definition of a calorie is the amount of energy necessary to raise the temperature of 1 gram (g) of water through 1° Celsius.
The type and amount of food people eat determine how many calories they consume. If a person consistently consumes more energy than they require, they will gain weight. Similarly, if they consume less, they will lose weight, fat, and eventually muscle mass.
According to the 2020-2025 Dietary Guidelines for Americans, adult females are likely to require between 1,600–2,400 calories a day, and adult males from 2,200–3,000.
However, this depends on their age, size, height, lifestyle, overall health, and activity level. As such, many more factors than just how many calories a person consumes plays a role in maintaining weight.
The 2020-2025 Dietary Guidelines for Americans recommend a calorie intake that
General guidelines advise that people require most calories in their adolescence and as young adults. As people get older, their metabolic rate
As such, this reduces their need for energy. For example, from age 19–25 years, the recommended intake for females is between 2,000–2,400 calories a day. But from 61+, this range drops to 1,600–2,000 calories a day.
Below, is the recommend calorie intake, separated by age and sex, from the Dietary Guideline for Americans.
| Age | Calories (males) |
|---|---|
| 16–18 | 2,400–3,200 |
| 19–20 | 2,600–3,000 |
| 21–35 | 2,400–3,000 |
| 36–40 | 2,400–2,800 |
| 41–55 | 2,200–2,800 |
| 56–60 | 2,200–2,600 |
| 61–75 | 2,000–2,600 |
| 76+ | 2,000–2,400 |
| Age | Calories (females) |
|---|---|
| 16–18 | 1,800–2,400 |
| 19–25 | 2,000–2,400 |
| 26–30 | 1,800–2,400 |
| 31–50 | 1,800–2,200 |
| 51–60 | 1,600–2,200 |
| 61+ | 1,600–2,000 |
For the human body to remain alive, it needs energy. The brain consumes around 20% of the metabolic energy people consume from food.
The basal metabolic rate (BMR) accounts for most of a person’s energy needs. This refers to the energy people require each day to sustain their basic life functions, such as blood circulation, digestion, and breathing.
Health experts use the term energy expenditure to describe the total amount of energy people use. It is the sum of the BMR, the thermic effect of food, which is the energy necessary to digest and absorb food, and the energy people use with physical activity.
As such, to maintain bodyweight, people must balance the energy they consume from food with the energy they use. This is why when people wish to lose weight, they can increase their amount of physical activity so they burn more calories, meaning their energy expenditure exceeds their energy intake.
Read on to learn more about how many calories a person burns a day.
Some tips for burning energy and losing weight more effectively may include:
1. Eating breakfast: A protein and healthy fat for breakfast can keep a person feeling fuller for longer and help prevent snacking during the day.
2. Eating regular meals: This can help burn calories more effectively and helps prevent mindless snacking.
3. Remembering “five-a-day:” Fruits and vegetables can be a tasty snack and they can bulk out meals. They are high in nutrients and fiber and low in calories and fat.
4. Eating slow-burning calories: High-fiber carbohydrates, such as legumes, and healthy fats, such as avocado, take longer to release energy, so will stop a person getting hungry as quickly.
5. Exercising: This can help burn off extra calories. People can try incorporating physical activities, such as walking, swimming, or playing sports.
6. Drinking water: Proper hydration is essential for good health. People can also swap out sodas for water as a healthier alternative.
7. Eating more fiber: Fiber, found in fruits, vegetables, and wholegrains, can help a person feel full and encourage healthy digestion.
8. Checking the label: Some items have hidden fats or sugars. As such, it is advisable for people to read the label on foods and beverages to help track what they are consuming.
9. Appropriate portions: People may unknowingly consume larger portions than they require. People can also use resources to ensure they have suitable amounts from each food group.
10. Slowing down: It is advisable to eat slowly and rest between courses or extra servings, as it can take up to 30 minutes for the body to realize it feels full.
11. Making a shopping list: Preparing a shopping list can help a person to plan healthful meals and snacks when they go grocery shopping.
12. Small treats: Banning foods can lead to cravings and bingeing. Occasionally, a person can enjoy their favorite treat, but in smaller amounts.
13. Getting enough sleep: Sufficient sleep is essential for good health. Sleep loss can affect metabolism, which may result in weight gain.
14. Avoid eating 2 hours before bed: Eating within 2 hours of sleeping can interfere with sleep quality and promote weight gain.
Here are some examples of activities and the calories they burn in 30 minutes. The estimates are for a person weighing 125 pounds.
| Activity | Calories burned |
| Lifting weights | 90 |
| Aqua aerobics | 120 |
| Walking at 4 miles an hour | 135 |
| General swimming | 180 |
| Running at 6 miles an hour | 495 |
| General gardening | 135 |
| Sleeping | 19 |
Keeping calorie intake within certain limits will not ensure a healthful diet, as different foods have different effects on the body.
Counting calories can help to maintain a healthy weight, but 100 calories looks very different depending what foods a person eats. For example, 100 calories from foods such as chips, chocolate, and cake are much smaller portion sizes than 100 calories from fruits or vegetables.
As such, instead of focusing solely on calories, it is important for a person to follow a balanced dietary plan and consume suitable amounts from each macronutrient and food group. For example,
Counting calories is not recommended for people with a history of disordered eating, as it can make symptoms
To help work out how much calories a person requires per day, they can attempt to calculate their BMR. However, it can be very difficult to measure BMR outside of clinical settings.
As a result, it is unlikely that a person could accurately calculate their BMR at home. As a simpler alternative, people can try calculating their resting metabolic rate (RMR). The RMR estimates the number of calories a person burns during a period of inactivity
One useful way of estimating RMR is the Mifflin-St. Jeor equation:
Male: 9.99 x weight (kg) + 6.25 x height (cm) – 4.92 x age + 5
Female: 9.99 x weight (kg) + 6.25 x height (cm) – 4.92 x age – 161
People can also calculate their RMR using an online calculator, such as the one provided by the American Council on Exercise (ACE), here.
Some FAQs about calories and how many to consume in a day may include:
How many calories should I be eating a day to lose weight?
Calculating how many calories to consume to help aid weight loss will vary from person to person. It is important to consider different factors such as sex, age, and activity levels. In general, if a person wishes to lose weight, they may want to consider reducing their daily calories so they are in a calorie deficit.
Read on to learn more about how many calories to consume to lose weight.
Is it safe to eat 1200 calories a day?
Although people may consider following a 1200 calories diet to lose weight, it is unlikely for most healthy adults to get sufficient energy or nutrients eating 1200 calories or less a day. As such, it is not advisable to regularly consume 1200 calories or less a day.
How many calories should I eat a day by age?
Rough guidelines for calories per day by age and sex are:
- Females 19–30: 1,800–2,400 calories
- Males 19–30: 2,400–3,000 calories
- Females 31–59: 1,600–2,200 calories
- Males 31–59: 2,200–3,000 calories