“Just eat less” is technically correct and almost completely useless advice. The question isn’t whether to eat less — it’s how much less, for you, right now, given your actual life. That’s what this guide answers.
Why There’s No Universal Number
The most common answer you’ll find online is 2,000 calories for women, 2,500 for men. These are population averages baked into nutrition labeling guidelines — not personal recommendations. A 5’4” sedentary woman in her 50s and a 5’11” woman who trains five days a week have almost nothing in common metabolically, yet both get the same “2,000 calorie” label.
The number that actually matters for you is your Total Daily Energy Expenditure (TDEE) — the total calories your body burns in a day, including everything from keeping your heart beating to your Tuesday spin class.
How to Estimate Your TDEE
Your TDEE has four components:
- BMR (Basal Metabolic Rate): Calories burned at complete rest — the energy cost of just existing
- NEAT (Non-Exercise Activity Thermogenesis): Fidgeting, walking to the kitchen, standing at your desk
- EAT (Exercise Activity Thermogenesis): Deliberate workouts
- TEF (Thermic Effect of Food): Energy used to digest and process what you eat — roughly 10% of total intake
The most widely used formula for estimating BMR is Mifflin-St Jeor:
Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Once you have your BMR, multiply by an activity multiplier:
| Activity Level | Multiplier |
|---|---|
| Sedentary (desk job, little exercise) | 1.2 |
| Lightly active (1–3 days/week exercise) | 1.375 |
| Moderately active (3–5 days/week) | 1.55 |
| Very active (6–7 days/week hard training) | 1.725 |
| Athlete / physical job | 1.9 |
The result is your estimated TDEE — the number of calories you need to maintain your current weight.
Adjusting for Your Goal
Once you have your maintenance number, adjusting for a specific goal is straightforward:
Weight Loss
Research consistently points to a deficit of 300–500 calories per day as a sustainable starting point — enough to produce roughly 0.3–0.5 kg (0.5–1 lb) of fat loss per week without tanking energy or triggering the aggressive hunger that kills adherence. Larger deficits (500–750 kcal) can work short-term but evidence suggests they increase muscle loss and metabolic adaptation over time.
Weight Gain / Muscle Building
A modest surplus of 200–300 calories above maintenance is typically sufficient to support muscle growth while minimizing fat gain. More isn’t better here — excess calories beyond what muscle synthesis can use end up stored as fat.
Maintaining Your Weight
Eat at TDEE. Simple in theory, harder in practice — mostly because most people significantly underestimate how many calories are in restaurant meals, cooking oils, and drinks.
Why the Formula Is Just a Starting Point
Formulas give you a reasonable first estimate — not a biological fact. Several things make your true TDEE different from the calculation:
Metabolic variability. Studies suggest individual metabolic rates can vary by 200–300 calories even between people with identical body composition and activity levels.
Body composition. Muscle burns more calories at rest than fat. Two people who weigh the same but have different muscle-to-fat ratios will have meaningfully different BMRs.
NEAT is wildly variable. Some people unconsciously move more when they eat more (fidgeting, pacing, gesturing). Research indicates NEAT can vary by up to 2,000 calories per day between individuals — which is one reason some people seem to “get away with” eating more.
Adaptation over time. As you lose weight, your TDEE decreases — both because you’re lighter and because the body partially adapts. A target that produces a 500-calorie deficit today will produce a smaller deficit six months from now.
This is why tracking what you actually eat matters more than getting the math perfect upfront. If you’re eating your calculated maintenance calories and gaining weight, your real TDEE is lower than estimated. If you’re losing faster than expected, it’s higher.
Common Reasons Your Calorie Count Feels Wrong
Underlogging cooking oils and fats. A tablespoon of olive oil is 120 calories. Most people pour two or three without thinking.
Forgetting liquid calories. A flavored coffee drink, a glass of juice, or a few glasses of wine can easily add 300–600 calories to a day that felt “clean.”
Eyeballing portions. Research indicates people typically underestimate restaurant portion sizes by 30–50%. Homemade meals aren’t immune — a “handful” of granola or a “drizzle” of dressing can vary 2–3x depending on the day.
Weekend drift. Monday through Friday discipline followed by loosened tracking on weekends is one of the most common reasons the scale doesn’t move. Studies suggest people eat an average of 400–600 more calories on weekends.
A Realistic Way to Use This Information
Start with the formula — it gives you a reasonable target. Then track your actual intake for two to three weeks and compare it to what the scale is doing. If your weight is holding steady at a number lower than your calculated TDEE, your true maintenance is lower. Adjust and keep going.
The goal of knowing how many calories you should eat isn’t to count forever. It’s to build an accurate mental model of what different amounts of food actually look like, so that staying close to your target becomes intuitive.
Start Tracking with AIDente
AIDente makes it easy to go from “I have no idea how much I’m eating” to “I know exactly where my calories are coming from” — just photograph your meals and the app handles the logging. Whether you’re trying to hit a deficit, build muscle, or simply understand your eating patterns, AIDente gives you the data you need without the spreadsheet.