"How many calories should I eat?" is one of the most searched nutrition questions. The frustrating answer is: it depends. Your calorie needs are unique to you - your body, your activity, your goals.
But we can get you a reasonable estimate and, more importantly, help you understand what actually determines that number.
General Guidelines (Starting Points)
The NHS provides general guidance:
NHS Daily Calorie Estimates
| Category | Estimated Daily Calories |
|---|---|
| Women (average) | 2,000 kcal |
| Men (average) | 2,500 kcal |
These are rough averages for moderately active adults. They're starting points, not prescriptions. Your actual needs might be 1,600 or 3,000 depending on individual factors.
Factors That Determine Your Needs
1. Basal Metabolic Rate (BMR)
The calories your body burns at complete rest - just keeping you alive (breathing, circulation, cell repair). This accounts for 60-75% of total energy expenditure. Larger bodies and more muscle mass mean higher BMR.
2. Activity Level
How much you move beyond basic functions. A desk worker and a construction worker with identical bodies need vastly different calories. Exercise, daily steps, and occupation all matter.
3. Thermic Effect of Food
Energy used to digest food - about 10% of calories consumed. Higher protein diets have slightly higher thermic effect.
4. Age
Metabolism slows with age - roughly 1-2% per decade after 20. A 50-year-old needs fewer calories than they did at 25, all else being equal.
5. Body Composition
Muscle burns more calories than fat at rest. Two people of the same weight but different muscle mass have different calorie needs.
6. Goals
Maintenance (staying the same), weight loss (deficit), or muscle gain (surplus) all require different calorie targets.
Calculating Your Estimate
The most common method uses the Mifflin-St Jeor equation for BMR, then multiplies by an activity factor:
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Then multiply by activity factor:
- Sedentary (little/no exercise): BMR × 1.2
- Lightly active (1-3 days/week): BMR × 1.375
- Moderately active (3-5 days/week): BMR × 1.55
- Very active (6-7 days/week): BMR × 1.725
- Extra active (very hard daily exercise): BMR × 1.9
Example Calculation
30-year-old woman, 65kg, 165cm, moderately active:
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 1,381 kcal
Maintenance = 1,381 × 1.55 = ~2,140 kcal/day
For Different Goals
Weight Maintenance
Eat at your calculated maintenance level. If weight stays stable over weeks, you've found your number. If gaining, reduce slightly. If losing, increase slightly.
Weight Loss
Create a moderate deficit of 300-500 calories below maintenance. This produces steady 0.5-1lb loss per week. Larger deficits often backfire - too much hunger, metabolic adaptation, and muscle loss.
Muscle Gain
Small surplus of 200-300 calories above maintenance, combined with resistance training. Larger surpluses mostly add fat, not muscle.
Minimum Intakes
Don't go below 1,200 calories (women) or 1,500 calories (men) without medical supervision. Below these levels, it's very difficult to meet nutritional needs, and metabolic adaptation becomes significant.
The Problem With Calorie Counting
Calorie calculations are estimates, not precise measurements. They don't account for:
- Individual metabolic variation (genetics)
- Hormonal fluctuations
- Stress and sleep impacts
- Accuracy of food logging (most people underestimate)
- Metabolic adaptation over time
Use calorie targets as a guide, not gospel. Your body's actual responses - energy levels, hunger, weight trends - are better feedback than any formula.
When Not to Count Calories
Calorie counting isn't appropriate for everyone:
- History of eating disorders or disordered eating
- When it creates anxiety or obsession
- When it disconnects you from natural hunger cues
- Children and adolescents (unless under medical guidance)
Alternative approaches like intuitive eating, portion-based methods, or focusing on food quality over quantity work better for many people.
The Bottom Line
Your calorie needs are individual - affected by body size, activity, age, and goals. Use calculations as starting estimates, then adjust based on real-world results. And remember: food quality matters alongside quantity. 1,800 calories of whole foods and 1,800 calories of junk food aren't equivalent for health, even if they're the same number.