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Weight Loss Macro Calculator
Calculate the optimal macronutrient ratio for healthy, sustainable weight loss.
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Muscle Building
High-protein plan for a moderately active male aiming to gain lean mass
Key values: 30yo male · 80 kg · +15% surplus
Weight Loss
Balanced deficit plan for a lightly active female targeting steady fat loss
Key values: 28yo female · 65 kg · -25% deficit
Keto Diet
Very low carb, high fat plan for metabolic adaptation
Key values: 35yo male · 90 kg · Ketogenic
The Energy Balance Equation
Weight loss requires a caloric deficit — consuming fewer calories than your body expends:
A deficit of approximately 3,500 calories corresponds to about 1 pound (0.45 kg) of fat loss. A sustainable daily deficit of 500 calories produces roughly 1 lb/week of weight loss.
Recommended Macro Ratios for Fat Loss
| Macronutrient | % of calories | Cal per gram | Role in fat loss |
|---|---|---|---|
| Protein | 30–35% | 4 | Preserves muscle, highest satiety |
| Fat | 25–30% | 9 | Hormones, nutrient absorption |
| Carbohydrates | 35–45% | 4 | Energy for exercise, brain function |
Why Protein Matters Most
During a caloric deficit, the body can break down muscle for energy. Higher protein intake ( of body weight) helps preserve lean mass:
Thermic effect: Protein has the highest thermic effect of food (TEF) — your body uses 20–30% of protein calories just to digest it, compared to 5–10% for carbs and 0–3% for fat. This means 100 calories of protein yields only ~75 net calories.
Worked Example
TDEE (maintenance): 2,200 cal. Target deficit: 500 cal. Weight: 80 kg.
| Macro | Target | Grams | Calories |
|---|---|---|---|
| Calories | — | — | 1,700 |
| Protein (30%) | 1.6× body weight | 128 g | 512 |
| Fat (30%) | — | 57 g | 510 |
| Carbs (remainder) | — | 170 g | 678 |
Sustainable Rate of Weight Loss
- 0.5–1 lb/week (0.25–0.5 kg): Sustainable, minimal muscle loss
- 1–2 lb/week: Aggressive but feasible with high protein
- >2 lb/week: Very aggressive — higher muscle loss risk, harder to maintain
The leaner you are, the slower you should lose. A safe guideline:
Frequently Asked Questions
What macro ratio is best for weight loss?
A commonly recommended split for fat loss is 30-35% protein, 25-30% fat, and 35-45% carbohydrates. High protein is prioritized because it preserves muscle mass during a caloric deficit and has the highest satiety effect.
How much protein do I need when losing weight?
Aim for grams of protein per kilogram of body weight to preserve lean muscle mass. The body can break down muscle for energy during a deficit, and higher protein intake counteracts this.
What is the thermic effect of food?
The thermic effect of food (TEF) is the energy your body uses to digest food. Protein has the highest TEF at 20-30%, meaning 100 calories of protein yields only about 75 net calories. Carbs have a TEF of 5-10%, and fat is 0-3%.
How fast should I lose weight?
A safe rate is 0.5 to 1 percent of body weight per week, or roughly 0.5-1 lb (0.25-0.5 kg) per week. The leaner you are, the slower you should lose. Very aggressive deficits above 2 lbs per week increase muscle loss risk.
Do I need to track macros or just calories for weight loss?
Calories determine whether you lose weight, but macros determine what you lose. Without adequate protein, you will lose more muscle along with fat. Tracking macros ensures you preserve muscle, maintain energy, and support hormonal health during a deficit.
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