The nutrition math (simple, transparent, useful)

This advisor uses a widely used calorie estimation framework: estimate your baseline energy needs (BMR), multiply by an activity factor to get maintenance calories (TDEE), then adjust calories up or down depending on your goal. We then allocate macros with a “protein-first” rule because protein tends to support satiety, recovery, and body composition. Finally, we compute a Food Quality Score (0–100) from a few high-leverage habits that usually matter more than perfection.

BMR is an estimate of how many calories your body uses per day at rest. We use the Mifflin–St Jeor equation (commonly used in practical nutrition coaching):

• Men: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + 5
• Women: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age − 161

Think of BMR as your “engine idle.” It’s not perfect (no formula is), but it’s a decent starting point for planning. If you track food intake and weight for 2–4 weeks, you can refine the estimate later based on real results.

Your body uses additional energy for movement, exercise, digestion, and daily life. We multiply BMR by an activity factor to estimate maintenance calories: TDEE = BMR × activity. The activity multiplier is your best guess of how active your average week is (including steps).

To lose fat, you generally need a calorie deficit; to gain muscle, you generally need a small surplus. The “Goal speed” slider sets the size of that adjustment. A practical rule of thumb: roughly 7,700 calories ≈ 1 kg of body mass. So losing 0.5 kg per week corresponds to about 0.5 × 7,700 ÷ 7 ≈ 550 calories/day deficit. We cap the deficit/surplus to keep recommendations reasonable and avoid extreme targets.

Macros are converted with standard calorie values: protein = 4 kcal/g, carbs = 4 kcal/g, fat = 9 kcal/g. This tool sets protein using a grams-per-kg slider (1.2–2.4 g/kg). Higher protein is often helpful during fat loss, higher training volume, or when appetite is high. After protein is set, we allocate fats to a moderate range (enough for satiety and hormones), and carbs fill the remaining calories.

Hydration needs vary with climate, training, and salt intake. A common baseline is 30–35 ml per kg body weight per day (so ~2.1–2.5L for a 70 kg person), plus extra for exercise. This advisor uses weight-based guidance and compares it to your water slider to give a gentle nudge.

The quality score is not a moral judgment — it’s a “defaults” indicator. It rewards: (1) more veg/fruit, (2) adequate protein, (3) adequate water, (4) lower ultra‑processed load, and (5) consistency. These are chosen because they tend to improve results across many goals without needing perfect tracking.

If you want to use this tool without counting calories every day, that’s totally valid: set your protein, aim for a consistent “plate template,” and watch your trend over time. Most people do better by improving defaults than by seeking the perfect plan.

Three real-world scenarios

Example 1: Fat loss without misery. A 30‑year‑old, 170 cm, 70 kg person, moderate activity, goal “Lose fat” at 0.5 kg/week, protein 1.8 g/kg, veg 5/day, water 2.5L, ultra‑processed 2/10, consistency 7/10. The tool typically recommends a moderate deficit and a protein-forward macro plan. The quality score will be high because the basics (protein + plants + water) are strong.

Example 2: Maintenance for performance. Same person but goal “Maintain,” protein 1.6 g/kg, water 2.3L, veg 4/day. Calories land near maintenance. This is the “strong default” plan for busy weeks when you want stable energy and decent recovery. You can still improve body composition slowly just by training well and keeping quality high.

Example 3: Lean muscle gain. Goal “Gain muscle,” slower speed (0.25 kg/week) with protein 1.8–2.2 g/kg. The plan suggests a small surplus. The quality score matters here too: surplus calories from mostly whole foods tends to feel better and supports training.

• Calories: start here, then adjust based on 2–4 weeks of trend data.
• Protein: treat as your “anchor.” Hitting protein often improves everything else.
• Carbs/fats: flexible. Prefer the split you can stick to consistently.
• Quality score: if it’s low, don’t change everything — fix one lever first.

• ½ plate veg/fruit
• ¼ plate protein
• ¼ plate carbs (or extra veg if sedentary)
• + a thumb of healthy fat (olive oil, nuts, avocado) if needed

If tracking feels overwhelming, use the plate template and focus on daily consistency. In many cases, consistency beats perfect macro math.

Frequently Asked Questions

• Is this medical advice?

  No. This is an educational planning tool. If you have medical conditions, are pregnant, have a history of eating disorders, or take medications that affect appetite/metabolism, work with a qualified clinician.

• Why do my calories look different from another calculator?

  Different tools use different equations and assumptions. Treat any output as a starting estimate. Your real-world trend (weight, measurements, performance, hunger) is the truth.

• Do I need to track macros daily?

  No. For many people, tracking for 1–2 weeks teaches portion awareness, then you can switch to a template approach. Protein + plants + hydration are high-value even without tracking.

• How fast should I lose weight?

  A common sustainable range is 0.25–0.75 kg/week depending on starting point. Faster loss can be harder to maintain and may affect training and mood. Choose the speed that supports consistency.

• What about intermittent fasting, keto, vegan, etc.?

  Diet styles can work if they help you maintain a calorie target and high-quality intake. This advisor is “style-agnostic.” Use the macro plan as a flexible target and choose foods that fit your preference.

• What does the Food Quality Score actually measure?

  It’s a fast proxy for the habits most correlated with good outcomes: veg/fruit intake, protein adequacy, hydration, lower ultra‑processed load, and consistency. It’s not a judgment and it won’t capture every nuance (like micronutrients), but it’s very actionable.

How to use this tool safely

Use the output as a starting point. If you notice obsessive tracking, anxiety around food, binge–restrict cycles, or compulsive exercise, pause and seek support — you deserve help. If you have medical conditions or unique nutrition needs, a registered dietitian can tailor guidance to you.

• Pick a plan and follow it for 2 weeks.
• Track a simple trend (morning bodyweight average, waist, training performance).
• If losing: not trending down? reduce ~150–200 kcal/day or add steps. If losing too fast: add calories.
• If gaining: not trending up? add ~150–200 kcal/day. If gaining too fast: reduce slightly.

• Don’t overhaul everything at once. Improve one lever by ~10% (veg +1 serving/day, water +0.5L/day, protein +20g/day).
• Re-check your Food Quality Score after a week.

Make it stick (without willpower)

• Protein first: set a default breakfast or lunch that hits 25–40g protein.
• Veg default: keep one “easy veg” always available (baby carrots, frozen mix, salad kit).
• Water trigger: drink after bathroom breaks or before coffee.
• Ultra‑processed guardrails: buy single servings, not family packs.
• Consistency strategy: aim for “80% good enough,” not perfect.