How Many Calories Should You Eat per Day?

1. Start by finding your maintenance calories

Your maintenance calories are the average intake that broadly keeps your weight stable under your current activity conditions. This is not limited to calories burned during exercise: it includes your resting metabolism, digestion, steps, spontaneous movement, work, and training.

The number depends on factors including age, weight, height, metabolism, sex, and physical activity. The NIDDK Body Weight Planner uses this information to provide a starting point and also shows how changing activity affects the intake needed to reach and then maintain a given weight. NIDDK — Body Weight Planner

A calculator cannot know your actual step count, how much food you may underestimate, your spontaneous activity, or your adaptations to dieting with complete accuracy. Treat its result as a hypothesis to test, never as a verdict on your metabolism.

2. Use a formula as your starting point

The Mifflin-St Jeor equation first estimates resting energy expenditure. It was developed from 498 healthy adults: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then +5 for men or −161 for women in the original equation. A calculator then applies an activity assumption to approximate total daily energy expenditure. Mifflin et al., 1990

For example, for a 30-year-old man who weighs 70 kg and is 175 cm tall, the formula estimates roughly 1,649 kcal at rest. This is not his calorie target: his steps, work, training, and digestion must still be covered. Depending on the activity level selected, a calculator might turn this estimate into maintenance calories of around 2,400 kcal.

Even the best equations remain imperfect for an individual. A systematic review found that Mifflin-St Jeor came closer to measured values more often than several common formulas, while still highlighting substantial errors and underrepresented populations. In athletes, a more recent meta-analysis found Ten-Haaf to be the most accurate and precise overall, while Mifflin-St Jeor frequently underperformed. This reinforces the need to calibrate any formula against the trend you actually observe. Frankenfield et al., 2005, O’Neill et al., 2023

• Enter your weight, height, age, and activity level honestly.
• Choose the more conservative activity level if you are unsure between two options.
• Round the result to a simple target, such as 2,400 rather than 2,437 kcal.
• Test that target before switching formulas or calculators.

3. Approximate your current maintenance over 14 days

Keep the estimate you obtained and make your conditions as comparable as possible for two weeks. Weigh yourself regularly under similar conditions, calculate the average for each week, and keep your steps consistent. A single day’s weight can fluctuate because of water, salt, carbohydrates, digestion, or the menstrual cycle.

If the two weekly averages remain close and your waist measurement does not clearly change, your average intake is probably close to your current maintenance. If the trend moves down, you are in a deficit; if it rises consistently, you are in a surplus. A change during the first few days is not enough to draw a conclusion.

The accuracy of your tracking matters as much as the accuracy of the formula. Oils, sauces, drinks, unweighed portions, and weekend meals can create a meaningful discrepancy. The goal is not to be perfect forever, but to collect two sufficiently consistent weeks of data so you can make a useful decision.

• Calories actually consumed each day.
• Body weight and a seven-day moving average.
• Daily step count.
• Waist measurement taken under the same conditions.
• Weights, repetitions, hunger, sleep, and recovery.

4. Adjust calories to your goal

To maintain your weight, stay close to your observed maintenance. To lose fat, an initial deficit of roughly 300 to 500 kcal per day is often large enough to measure without making your diet unnecessarily aggressive. To build muscle, a small surplus of roughly 150 to 300 kcal limits the fat you may need to lose later. Shredy guide — how to lose belly fat

A larger deficit does not guarantee a better aesthetic result. A meta-analysis of resistance training during energy restriction linked prolonged deficits to poorer gains in lean mass and recommends avoiding deficits above roughly 500 kcal per day when preserving or developing lean mass is the priority. Murphy and Koehler, 2022

These numbers are starting points, not prescriptions. A smaller, sedentary person may need a smaller absolute deficit; a larger, active person may tolerate more. Assess the rate of progress, training performance, hunger, and recovery together.

• Fat loss: observed maintenance − roughly 300 to 500 kcal.
• Muscle gain: observed maintenance + roughly 150 to 300 kcal.
• Maintenance or body recomposition: stay close to maintenance and focus on progressing in training.
• Plateau: check adherence and activity before cutting calories again.

5. Women and men: why an average number is not enough

Average needs differ partly because average weight, height, and lean mass differ. But automatically assigning 2,000 kcal to every woman and 2,500 kcal to every man ignores activity, body size, age, and goals.

A tall, active woman may expend more energy than a shorter, sedentary man. Conversely, two people with the same measurements may differ because of their steps, muscle mass, or dieting history. Use the sex coefficient in the formula as a statistical estimate, then let your actual weight trend settle the question.

During pregnancy, breastfeeding, growth, or illness, both needs and risks change. In these situations, a number found in an article cannot replace individual medical or dietetic care.

6. Will eating 1,500 calories a day make you lose weight?

Only if 1,500 kcal is below your actual energy expenditure. For a smaller, less active person, it may create a moderate deficit or even sit close to maintenance. For a taller, very active, or muscular person, it may create an excessive deficit.

A low number is not the goal. Look for gradual weight loss with manageable hunger, adequate sleep, and training performance that remains as stable as possible. If you think you need to go extremely low to lose weight, first check your portions, drinks, steps, and how long the plateau has actually lasted.

A very low intake, rapid weight loss, dizziness, persistent fatigue, food obsession, or disrupted menstrual periods are reasons to stop escalating the restriction and consult a healthcare professional.

7. Allocate your calories without neglecting macronutrients

Total calorie intake primarily determines how your weight changes, but two diets with the same energy content do not necessarily provide the same satiety, training performance, or nutritional quality.

For a healthy adult who resistance trains, 1.6 to 2.2 g/kg/day of protein is a practical target that covers most situations. The ISSN considers 1.4 to 2.0 g/kg/day sufficient for most exercising people, with higher intakes sometimes useful during a deficit. For fat, 0.5 to 0.8 g/kg/day is a practical starting point to individualize; natural-bodybuilding literature also uses 15% to 30% of calories. Allocate the remaining calories to carbohydrates to support training. Jäger et al., 2017, Helms et al., 2014, Shredy guide — daily protein for muscle gain

Also aim for fruit, vegetables, minimally processed foods, and roughly 10 to 15 g of fiber per 1,000 kcal if you tolerate it well. The established reference value is 14 g per 1,000 kcal. A diet built from nutritious foods 80% to 90% of the time can still leave room for foods you enjoy without losing sight of your average target. Dietary Fiber, 2021

8. Your maintenance calories can change

Maintenance is not a permanently fixed number. It varies with your weight, steps, training, spontaneous movement, and adaptations to restriction. The NIDDK notes that after weight loss, a lighter body generally needs fewer calories to maintain its new weight. NIDDK — Losing or maintaining weight

An additional adaptation in energy expenditure can also occur during weight loss, even after accounting for changes in weight and body composition. Its size varies and does not mean that calories stop mattering: it explains why an old estimate may sometimes need to be recalibrated. Müller and Bosy-Westphal, 2013

A fitness tracker can help you keep your steps consistent, but avoid automatically eating back every calorie it reports. A systematic review of 158 publications concluded that consumer wearables measured steps and heart rate more accurately than energy expenditure, for which none of the brands studied was accurate. Fuller et al., 2020

To make comparisons useful, keep a step target that is high but sustainable and avoid alternating 3,000-step days with 20,000-step days. Your training should preserve or develop muscle, not simply burn as many calories as possible during each workout.

9. Adjust one variable at a time

After 14 days, stay the course if the trend matches your goal. If your average weight is not falling despite a presumed deficit and good adherence, reduce your intake by roughly 100 to 200 kcal or modestly increase your steps, then observe again. Do not change calories, cardio, steps, and your training program at the same time.

If your weight is dropping too quickly, hunger becomes difficult to manage, and performance declines, add roughly 100 to 200 kcal or reduce part of your energy expenditure. During a muscle-gain phase, slow the surplus if your weight and waist measurement are rising faster than your performance.

If your data are incomplete, improve your tracking first. A “broken” metabolism is far less likely than an inaccurate estimate, variable activity, or unrecorded calories.

Key takeaways

The best calculation is one you compare with reality. A reasonable estimate, tracked consistently and corrected in small steps, is more useful than a supposedly exact number that you change every three days.

• Estimate your maintenance calories with a reputable calculator.
• Keep your calories, steps, and training consistent for 14 days.
• Watch your average weight, not one isolated weigh-in.
• Apply a moderate deficit or a small surplus according to your goal.
• Keep enough protein, fat, carbohydrates, and fiber in your diet.
• Make small adjustments only when the trend supports them.