How Many Calories Should I Eat? (Personalized Guide)
How many calories you should eat depends on your basal metabolic rate (BMR) — the energy your body burns at rest — multiplied by your activity level to give your total daily energy expenditure (TDEE). For weight loss, eat 300–500 calories below your TDEE. For maintenance, eat at your TDEE. For muscle gain, eat 200–300 calories above. The average adult TDEE ranges from 1,600 to 3,000 kcal/day depending on individual factors.
The 2,000-calorie figure printed on food packaging is a regulatory average — a number chosen to be broadly representative, not individually accurate. Research consistently shows that actual calorie needs vary by 500–800 kcal per day between people of similar size and age, due to differences in body composition, metabolic rate, hormone levels, and activity.[1] For most people, the real number looks quite different from the label.
This guide explains the science behind how calorie needs are calculated, what your target should be based on your goal, and why even a perfectly calculated number is only part of the answer.
Step One: Calculate Your Basal Metabolic Rate
Your basal metabolic rate (BMR) is the number of calories your body burns simply to stay alive — to keep your heart beating, your lungs breathing, your organs functioning, and your body temperature stable. It represents the largest single component of daily calorie expenditure, accounting for roughly 60–70% of total daily energy use.[2]
The most scientifically validated method for estimating BMR is the Mifflin-St Jeor equation, developed in 1990 and consistently shown to outperform older formulas in accuracy across a range of populations.[3]
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
This figure is your starting point — the calories your body burns on a day when you do absolutely nothing. In reality, you move. Which means you need to account for that too.
02Step Two: Multiply by Your Activity Level
Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that reflects how much you move across an average day — not just intentional exercise, but also what researchers call Non-Exercise Activity Thermogenesis (NEAT): the energy burned through walking, standing, fidgeting, and all the incidental movement of daily life.[4] NEAT can vary by up to 2,000 calories per day between individuals, making it one of the most significant and underappreciated factors in individual calorie needs.
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little to no exercise, mostly sitting | × 1.2 |
| Lightly active | Light exercise 1–3 days/week, some walking | × 1.375 |
| Moderately active | Exercise 3–5 days/week, active lifestyle | × 1.55 |
| Very active | Hard exercise 6–7 days/week, physically demanding job | × 1.725 |
| Extremely active | Athlete-level training or heavy physical labour daily | × 1.9 |
Returning to the earlier example: a moderately active 38-year-old woman with a BMR of 1,360 has a TDEE of approximately 2,108 kcal/day (1,360 × 1.55). That is her maintenance calorie level — the point at which her weight stays stable.
The most common error is choosing "sedentary" when "lightly active" is more accurate, or "lightly active" when daily walking, housework, and general movement put you closer to "moderately active". When in doubt, choose the higher category and monitor results — it's easier to adjust down than to discover you've been under-eating for weeks.
Step Three: Adjust for Your Goal
Once you have your TDEE, the adjustment for your specific goal is relatively straightforward. The principle is simple: a calorie deficit produces fat loss, a calorie surplus supports muscle gain, and eating at maintenance preserves current weight. The size of the adjustment determines the pace of change.
A deficit of 500 calories per day produces a theoretical loss of approximately 0.45 kg (1 lb) per week, based on the commonly cited estimate that 1 lb of fat stores roughly 3,500 kcal. In practice, actual weight loss is slightly more variable due to water retention, glycogen depletion, and metabolic adaptation — but the 500 kcal deficit remains a reliable starting framework.[5]
The calorie target that produces results is not the lowest number you can tolerate. It's the right number for your body — precise enough to move toward your goal, sustainable enough to follow consistently.
Why Calorie Counting Alone Is Not Enough
Understanding your calorie target is necessary but not sufficient. Several factors make the "calories in, calories out" model more complex in practice than it appears on paper.
Metabolic adaptation
When calorie intake is reduced, the body responds by gradually lowering its energy expenditure — a phenomenon known as metabolic adaptation or "adaptive thermogenesis." This means that after several weeks on a calorie deficit, your TDEE itself has decreased, and the deficit you started with is now smaller than calculated. This is one of the primary reasons weight loss slows or plateaus even when nothing has changed in behavior. Adjustments to calorie targets over time, and periodic diet breaks, are tools used to manage this effect.
Macronutrient composition
Two people eating identical calories can have very different results depending on how those calories are distributed across protein, carbohydrates, and fat. Protein has a significantly higher thermic effect than the other macronutrients — meaning more of the calories from protein are "spent" on digestion rather than stored. Protein also has superior effects on satiety and muscle mass preservation during a deficit. The composition of a calorie budget matters almost as much as the size of it.
Individual variability
The equations above produce estimates. Research shows that even the most accurate BMR formulas can be off by 10–15% for any given individual.[1] This is why treating the output as a starting point — and adjusting based on observed results over 2–3 weeks — is more effective than rigidly following a calculated number without adjustment.
Start with your calculated TDEE minus 400 calories. Track your average weight daily for two weeks (morning, after bathroom, before eating). If you've lost 0.3–0.6 kg per week, your target is accurate. If you've lost more, increase by 100–150 kcal. If nothing has changed, decrease by 100–150 kcal. Two weeks is the minimum meaningful window — less than that captures too much normal fluctuation.
What a Personalised Plan Does That Math Can't
Calculating your TDEE and setting a calorie target is the starting point — but it leaves open the questions that determine whether you actually succeed: What do you eat to hit that number? How do you distribute meals across your day? How do you meet your protein, fibre, and micronutrient needs within your calorie budget? How do you handle social eating, travel, or the days when the plan falls apart?
These are the questions that a personalised meal plan answers — not a formula, but a structured, practical eating framework built around your target, your preferences, and your life. A plan that tells you exactly what to eat each day within your calorie budget, in meals you'll actually enjoy, structured around your actual schedule, removes the daily cognitive load of translating a number into food decisions. And removing that friction is, behaviorally, one of the most powerful things you can do for long-term adherence.
To lose weight, eat 300–500 calories below your Total Daily Energy Expenditure (TDEE). A deficit of 500 kcal/day produces approximately 0.5 kg of fat loss per week. To find your TDEE, calculate your BMR using the Mifflin-St Jeor equation and multiply by your activity factor. Start there, track your weight for two weeks, and adjust based on actual results rather than the theoretical number alone.
For most adults, 1,200 calories is below the threshold needed to meet basic nutritional needs — and significantly below what most people's actual TDEE would suggest as an appropriate deficit target. Very low calorie diets (under 1,200 kcal) can cause muscle mass loss, nutrient deficiencies, fatigue, and metabolic adaptation that makes long-term weight management harder. In most cases, a moderate deficit of 300–500 kcal below TDEE is more effective and sustainable.
Your maintenance calorie level is your TDEE — your BMR multiplied by your activity factor. For a sedentary adult woman this might be 1,700–1,900 kcal/day; for a moderately active adult man it might be 2,400–2,800 kcal/day. Individual variation is significant, so treating the calculated number as a starting estimate and adjusting based on two to three weeks of real-world results gives you the most accurate personalised maintenance figure.
Total calories drive weight change — you cannot lose fat in a calorie surplus, regardless of macros. But macronutrient composition significantly affects the quality of that weight change. Adequate protein (1.2–1.6g/kg) during a deficit preserves muscle mass and increases satiety. Fibre supports digestive health and appetite regulation. So the most accurate answer is: calories determine the direction, macros determine the outcome quality.
This is almost always metabolic adaptation. As body weight decreases, BMR decreases — meaning your TDEE has fallen and the deficit you started with no longer exists. Additionally, diet-induced reductions in NEAT (unconscious movement) can further reduce energy expenditure. The solution is to recalculate your TDEE at your new weight, reduce calories slightly, or take a structured maintenance break before continuing the deficit.
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- Thomas, D. M., Gonzalez, M. C., Pereira, A. Z., Redman, L. M., & Heymsfield, S. B. (2014). Time to correctly predict the amount of weight loss with dieting. Journal of the Academy of Nutrition and Dietetics, 114(6), 857–861.
- Hall, K. D., Heymsfield, S. B., Kemnitz, J. W., Klein, S., Schoeller, D. A., & Speakman, J. R. (2012). Energy balance and its components: implications for body weight regulation. The American Journal of Clinical Nutrition, 95(4), 989–994.
- Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247.
- Levine, J. A., Eberhardt, N. L., & Jensen, M. D. (1999). Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science, 283(5399), 212–214.
- Hall, K. D. (2008). What is the required energy deficit per unit weight loss? International Journal of Obesity, 32(3), 573–576.