How Many Calories Should I Eat a Day?

How many calories should I eat per day?

The honest answer is: it depends on your body size, age, sex and how active you are. As a broad guide, the Dietary Guidelines for Americans 2020–2025 estimate that adult women need about 1,600 to 2,400 calories a day and adult men about 2,000 to 3,000 calories a day to maintain their weight. The UK's NHS uses round reference values of about 2,000 kcal for women and 2,500 kcal for men. The low end of each range applies to smaller, older, sedentary people; the high end to younger, larger, active people.

The calorie calculator above gives a more personal estimate. It:

1. Estimates your resting energy needs with the Mifflin-St Jeor equation from your age, sex, weight and height.
2. Multiplies by an activity factor to estimate your maintenance calories (TDEE).
3. Adjusts for your goal – maintain, lose or gain weight at a chosen weekly rate – using approximately 7,700 kcal per kilogram of body weight.
4. Shows a protein guide of 0.8–1.2 g per kg of body weight.

It does not set targets below 1,200 kcal a day for women or 1,500 kcal a day for men; lower intakes are generally only advised with professional supervision. For the full explanation of the energy equations, see the TDEE calculator.

Estimated calories per day by age and activity

These estimates are from Table A2-2 of the Dietary Guidelines for Americans 2020–2025. They are calculated for a "reference" man of 5′10″ and 154 lb and a reference woman of 5′4″ and 126 lb – both at a healthy BMI – so larger people will usually need more and smaller people less.

Women

Men

In the guidelines, sedentary means only the light activity of daily life; moderately active means daily activity equivalent to walking about 1.5 to 3 miles a day at 3–4 mph, plus daily life; active means the equivalent of walking more than 3 miles a day at that pace, plus daily life.

Calories to lose weight

To lose weight, you need to take in fewer calories than you use. The calculator applies a daily deficit based on your chosen rate:

Why weight loss slows down: the "3,500 calories per pound" rule is a reasonable guide for the first few weeks, but research by the US National Institutes of Health showed that it overestimates long-term weight loss. As you lose weight, your body needs fewer calories, so the same intake produces a smaller deficit. The NIDDK Body Weight Planner, based on that research, models this dynamic change and is a useful tool for longer-term planning. In practice, recalculating your needs every 4–5 kg of weight change, and adjusting based on your actual progress, works well.

Worked examples

• Woman, 40, 68 kg, 165 cm, lightly active, maintain: BMR ≈ 1,350 kcal; × 1.375 ≈ 1,860 kcal/day.
• Man, 45, 95 kg, 180 cm, lightly active, lose 0.5 kg/week: BMR ≈ 1,855 kcal; maintenance ≈ 2,550 kcal; target ≈ 2,000 kcal/day.
• Man, 25, 68 kg, 178 cm, moderately active, gain 0.25 kg/week: BMR ≈ 1,673 kcal; maintenance ≈ 2,590 kcal; target ≈ 2,870 kcal/day.

Quality matters as well as quantity

Calories determine weight change over time, but the kind of food affects how full you feel, how easy a diet is to sustain, and your long-term health. The Dietary Guidelines recommend a pattern built around:

• Vegetables of all types and fruits, especially whole fruits.
• Grains, at least half of which are whole grains.
• Dairy or fortified soy alternatives.
• Protein foods – lean meats, poultry, eggs, seafood, beans, peas, lentils, nuts, seeds and soy products.
• Oils, including vegetable oils and those in foods such as seafood and nuts.

and limiting added sugars to less than 10% of calories, saturated fat to less than 10% of calories, sodium to under 2,300 mg a day, and alcohol.

Protein

The calculator shows a protein range of 0.8–1.2 g per kg of body weight. The lower figure (0.8 g/kg) is the Recommended Dietary Allowance for adults; somewhat higher intakes are often suggested for older adults, during weight loss to help preserve muscle, and for people who train regularly. People with kidney disease may need different targets – ask your clinician.

Reading food labels

Nutrition Facts labels in the US list calories per serving and the % Daily Value based on a 2,000-calorie diet. That figure is a reference for comparing foods, not a recommendation for everyone. Check the serving size first – many packages contain more than one serving.

Where calories come from

Calories are a unit of energy. On food labels, "calories" means kilocalories (kcal); in some countries energy is also shown in kilojoules (1 kcal = 4.184 kJ). Each macronutrient provides a different amount of energy:

This is why foods high in fat, or drinks high in alcohol and sugar, can add many calories in small volumes, while vegetables, fruit, soups and other foods with high water and fibre content provide relatively few calories for their volume.

Energy density and fullness

Energy density is the number of calories in a given weight of food. Diets built around lower-energy-density foods – vegetables, fruit, legumes, whole grains, lean proteins, soups – tend to help people feel full on fewer calories. In tightly controlled feeding studies at the NIH, people offered ultra-processed diets ate more calories and gained weight compared with when they were offered minimally processed diets matched for the nutrients presented, suggesting that the type of food influences how much we eat.

Drinks count

Sugary drinks, fruit juices, specialty coffees and alcohol can contribute several hundred calories a day without making you feel full. Switching some of them for water, unsweetened tea or coffee is one of the simplest ways to reduce intake.

Splitting your calories between protein, carbs and fat

The Dietary Guidelines for Americans use the Acceptable Macronutrient Distribution Ranges (AMDRs) for adults: 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat. These ranges are wide on purpose – many eating patterns can be healthy. The table converts them into grams for common calorie targets (protein and carbohydrate at 4 kcal/g, fat at 9 kcal/g):

The same guidelines recommend keeping added sugars to less than 10% of calories per day and saturated fat to less than 10% of calories per day from age 2. On a 2,000-calorie intake, 10% is 200 calories – about 50 g of added sugar or 22 g of saturated fat.

Spreading calories across the day

There is no single correct meal pattern. Some people prefer three meals; others prefer smaller meals with snacks. A simple way to plan a 2,000-calorie day is roughly 400–600 calories per main meal with one or two 150–250-calorie snacks, but timing matters far less than the total and the quality of the food. If you are taking glucose-lowering medicines such as insulin, ask your care team before changing your meal pattern, because the timing of food and medicine needs to match.

Calorie needs across life

Calorie needs rise through childhood and adolescence, peak in late adolescence and early adulthood, and decline gradually with age as muscle mass and activity tend to fall. The Dietary Guidelines estimates for sedentary men, for example, fall from about 2,600 kcal at 19–20 to about 2,000 kcal from age 61 onwards. Staying active and maintaining muscle with strength training helps keep energy needs – and appetite regulation – closer to those of younger adults. Older adults often need fewer calories but the same or more protein and micronutrients, which makes food quality especially important.

A step-by-step way to set your daily calories

1. Start with the estimate from the calculator for your age, sex, size and activity.
2. Pick a realistic goal. For most people, 0.25–0.5 kg (½–1 lb) a week is sustainable.
3. Plan meals around protein, vegetables and whole foods, then fill in the rest.
4. Track honestly for two to three weeks – intake and weekly average weight.
5. Adjust in small steps of 100–200 kcal based on what actually happens.
6. Reassess after every 4–5 kg of weight change, or if your activity changes.
7. Pay attention to how you feel – energy, hunger, sleep, training – not just the scale.

Signs your calorie target needs adjusting

Weigh yourself under the same conditions several times a week and look at the weekly average – daily weight can swing by 1–2 kg with water, salt and food.

When a calorie calculator is not appropriate

• Pregnancy and breastfeeding: needs increase and should be guided by your maternity team.
• Children and teenagers: growing bodies have different needs; see the paediatric rows in the Dietary Guidelines.
• Eating disorders or a history of one: calorie counting can be harmful. Please seek support from a health professional.
• Medical conditions such as diabetes treated with insulin or sulfonylureas, kidney disease, or recent surgery: changes in intake should be planned with your care team.
• Older adults with unintended weight loss or frailty.