Everything you need for step-by-step fat-loss nutrition
Goal: lose fat while preserving muscle mass, improving your cardiovascular and hormonal health. Here you’ll learn how to calculate your BMR with Mifflin–St Jeor, set macros, use a gradual 200–300 kcal deficit, track progress with weight + tape measures + bioimpedance, and train smart.
Body composition > weight: why it matters
Your cardiometabolic health doesn’t come from the scale number, but from your body fat percentage and fat-free mass. More muscle and less visceral fat are associated with a healthier lipid profile, better insulin sensitivity, blood pressure, and hormonal balance. The plan: moderate deficit + adequate protein + resistance training + consistency.
Step 1 — Calculate your BMR and total energy expenditure
Your Basal Metabolic Rate (BMR) is the energy needed to maintain vital functions at rest. Calculate your BMR with Mifflin–St Jeor and multiply it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE).
| Formula | Equation | When to use |
|---|---|---|
| Mifflin–St Jeor | Men: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + 5 Women: BMR = 10·weight + 6.25·height − 5·age − 161 | General use; recommended starting point |
| Activity factors | Sedentary 1.2 · Light 1.4 · Moderate 1.6 · High 1.8 · Very high 2.0+ | TDEE ≈ BMR × factor |
Worked example
Person at 80 kg, 178 cm, 34 years, moderate activity (1.6). Mifflin (male): BMR ≈ 10·80 + 6.25·178 − 5·34 + 5 = 800 + 1112.5 − 170 + 5 ≈ 1747.5 kcal. TDEE ≈ 1748 × 1.6 ≈ 2800 kcal.
Step 2 — Gradual deficit: −200 to −300 kcal and reassess
Start with a moderate deficit of 200–300 kcal below your TDEE. Hold for 2–3 weeks while monitoring:
- Weekly average weight (weigh daily; the average is what matters).
- Tape measurements (waist, hips, thigh, arm) once/week.
- Bioimpedance (same time/conditions) 1–2×/week.
Step 3 — Macros that protect muscle
First set daily grams of protein, then a minimum healthy fat intake, and fill the rest with carbohydrates (CHO) to reach your calorie target, according to preferences and training. Remember to accompany your diet with essential micronutrients (omega-3, omega-6, vitamins, fiber, etc.).
| Macronutrient | Recommended range | Practical notes |
|---|---|---|
| Protein | 1.6–2.0 g/kg body weight | Foundation for muscle preservation in a deficit; repair and satiety |
| Fat | 0.4–0.8 g/kg | Hormonal support, fat-soluble vitamins; prioritize EVOO, nuts, oily fish |
| Carbohydrates | Calories left | Training fuel; adjust to volume/sets in zones Z4–Z5 |
Example at a 2200 kcal target
- Protein: 2.0 g/kg × 80 kg = 160 g → 640 kcal
- Fat: 0.6 g/kg × 80 kg = 48 g → 432 kcal
- Kcal left for CHO: 2200 − (640 + 432) = 1128 kcal → ≈ 282 g CHO
Step 4 — Train to lose fat, not muscle
It’s common to start a diet and drop weight quickly. Be careful: without adequate protein (+ resistance training), you’ll lose both fat and muscle. Muscle mass protects your hormonal and cardiovascular health. Here are some tips to keep it:
Strength (2–4 days/week)
- Prioritize compounds: squat, deadlift, bench/overhead press, rows, pull-ups.
- Moderate volume (8–12 sets/muscle/week), RIR 1–3.
- Minimum viable progressive overload: +1–2 reps or +2.5 kg when due.
Cardio that helps
- Z2: 2–4 sessions of 30–45′ (recovery and energy expenditure).
- Strategic HIIT: 1 session/week if you recover well.
- NEAT: 8–12k steps/day (or +20% vs. baseline).
Recovery
- Sleep 7–9 h; keep a consistent routine.
- Distribute protein (3–5 meals/day; 25–45 g/meal).
- Hydration and sodium on point, especially if you reduce carbs.
Avoid common traps
- Rapid “loss” from water: very low-carb diets drastically reduce glycogen and body water. You can “lose” ≈1–3 kg in 7–10 days. That’s not fat — it’s water.
- Over-aggressive hypocaloric plans: big cuts → hunger, fatigue, worse performance, and higher risk of muscle loss. Also, no one sustains them for long. The key is to learn to eat well for life, not crash-diet and then revert to old habits.
- “Eating clean” without counting: if you want precision, use ranges for macros and measurable portions.
- Tons of cardio without strength: favors lean mass loss if protein/stimulus are insufficient.
- No plan for social events: 80/20 strategy; compensate with NEAT and prioritize protein/veg.
Step 5 — Measure what matters
Weekly routine
- Weight: daily → use the weekly average.
- Tape measures: waist (umbilicus), hips, thigh, arm.
- BIA scale: same time, fasted, after bathroom, no prior training.
- Photos: even lighting, 3 angles, same distance.
Reading the data
- If weight stable but waist down → body recomposition, keep going.
- If plateau 14–30 days → −100/−150 kcal or +NEAT.
- If performance drops and hunger rises → add 100–150 kcal and prioritize sleep.
- Watch for physical/mental changes: fatigue, low mood, libido loss, amenorrhea, etc. These often arise with very restrictive deficits, especially at very low fat intakes. Consult a healthcare professional if any warning signs appear.
30-day checklist
| Day | Task | Done |
|---|---|---|
| 1 | Calculate BMR (Mifflin) and TDEE; set a −200/−300 kcal deficit | □ |
| 2 | Set macros (protein first, then minimum fat, rest CHO) | □ |
| 3 | Plan strength 3 days + Z2 2–3 days + 10k steps | □ |
| 7 | Review weekly average weight and tape measures | □ |
| 14 | If plateau, adjust −100/−150 kcal or +NEAT | □ |
| 21 | Assess performance and energy; fix sleep/stress | □ |
| 30 | Global review + photos; decide next microcycle | □ |
Six-line summary
- The goal is body composition, not an isolated weight number.
- Calculate BMR with Mifflin–St Jeor and apply a moderate deficit.
- Set high protein, minimum healthy fat, and CHO in service of training.
- Train strength + Z2 + NEAT; sleep 7–9 h.
- Monitor with weekly average weight, tape measures, and BIA.
- If you plateau ≥14–30 days, tweak lightly and stay consistent.
