Macro Calculator for Weight Loss
Counting calories gets you in a deficit — but counting macros determines **what you lose**. A weight-loss diet that's too low in protein will cost you muscle, leaving you lighter on the scale but softer in the mirror. Conversely, a well-structured macro split with adequate protein (1.6–2.2 g/kg bodyweight), moderate fat for hormonal health, and appropriately reduced carbohydrates lets you lose almost exclusively fat while maintaining strength and energy. This weight-loss macro calculator starts with your calorie target (ideally set using our TDEE calculator), then distributes it into a research-backed macro split optimised for fat loss. The default is 40% protein / 30% fat / 30% carbs, but you can adjust the sliders to fit your food preferences.
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Example Use Cases
An 80 kg male eating 2,100 kcal for weight loss: 210 g protein, 70 g fat, 158 g carbs at the 40/30/30 default. That's 2.6 g/kg protein — excellent for muscle retention.
A 60 kg female eating 1,500 kcal: 150 g protein, 50 g fat, 113 g carbs. If 150 g protein feels like too much food volume, she can shift to 35/30/35 and still get 131 g protein (2.2 g/kg).
How to Interpret Your Results
During a calorie deficit, protein needs are **higher** than during maintenance — not lower. Research by Helms et al. recommends 2.3–3.1 g/kg of lean body mass for natural athletes in a deficit. For non-athletes, 1.6–2.2 g/kg total bodyweight is a practical guideline.
Frequently Asked Questions
Methodology & Limitations
Formulas Used
Macro grams are derived from total calories: **Protein (g) = (calories × protein%) ÷ 4**, **Carbs (g) = (calories × carb%) ÷ 4**, **Fat (g) = (calories × fat%) ÷ 9**. Preset ratios are based on general sports-nutrition guidelines.
Page-Specific Notes
Default macro split for weight loss is 40P/30F/30C, based on sports nutrition consensus. Protein is set as the priority macro; remaining calories are split between fat and carbs.
Limitations
Optimal macro ratios vary by individual and depend on factors like training volume, body composition, metabolic health, and food preferences. Use presets as starting points and adjust based on your response over 2–4 weeks. Consult a registered dietitian for medical nutrition therapy.
Sources & Citations
- Jäger R, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
- Helms ER, et al. Evidence-based recommendations for natural bodybuilding contest preparation. J Int Soc Sports Nutr. 2014;11:20.
Medical Disclaimer: This calculator provides estimates based on published formulas and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your diet or exercise routine.
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