Sports Nutrition • 8 Min Read

Macronutrient Ratios for Cutting, Bulking & Maintenance: Protein (g/lb), Fat Floors & Carb Math

Author: Sports Nutrition & Metabolic Science • Published: August 2026 • Reviewed by: Registered Dietitian (RD, CSSD)

Healthy balanced macronutrient meal prep with lean proteins and complex carbohydrates

restaurant Calculating individual macronutrient targets: 4 kcal/g protein, 4 kcal/g carbs, and 9 kcal/g dietary fat Photo: Royalty-Free Unsplash

While total caloric intake dictates whether you gain or lose weight, your macronutrient distribution (Protein, Carbohydrates, Fats) determines whether that weight change consists of lean muscle tissue or adipose fat. Moving beyond arbitrary percentage splits (like the generic 40/40/20 rule) to gram-per-bodyweight formulas optimizes muscle protein synthesis while safeguarding hormonal health.

format_list_bulleted Table of Contents

1. Recommended Macro Splits (Cutting, Recomp & Bulking)
2. Protein Targets: The 0.8 to 1.2 g/lb Evidence-Based Range
3. The Essential Dietary Fat Floor (0.3 g/lb) for Hormonal Health
4. Allocating Remaining Calories to Carbohydrates & Glycogen
5. Worked Example: 180 lb Lifter on a 500-Calorie Fat Loss Cut

1. Recommended Macro Splits by Fitness Goal

Goal	Caloric Target	Protein Target	Dietary Fat	Carbohydrates
Fat Loss (Cutting)	TDEE − 20%	1.0 – 1.2 g / lb (Muscle sparing)	0.30 – 0.35 g / lb	Remaining calories
Body Recomposition	Exact TDEE (Maintenance)	0.9 – 1.0 g / lb	0.35 – 0.40 g / lb	Remaining calories
Lean Bulking	TDEE + 10%	0.8 – 1.0 g / lb	0.40 – 0.50 g / lb	High (Fuels training volume)

Nutritional calorie and macronutrient calculation spreadsheet — **Figure 1:** Always calculate protein and fats in absolute grams first, then fill remaining calorie budget with performance carbs. Macro Waterfall

2. Protein Targets: The Scientific Evidence

According to meta-analyses in the British Journal of Sports Medicine (Morton et al.), muscle protein synthesis plateaus at 1.6 g/kg (0.73 g/lb) to 2.2 g/kg (1.0 g/lb) of total bodyweight in energy balance. When in a caloric deficit (cutting), increasing protein to 1.0 to 1.2 g/lb prevents muscle catabolism and elevates satiety through the Thermic Effect of Food (TEF), which burns 20-30% of protein calories during digestion.

Athlete lifting weights in gym stimulating muscle protein synthesis — **Figure 2:** Spreading protein across 4 to 5 meals (0.4g/kg per meal) maximizes muscle protein synthesis via regular leucine thresholds. Protein Synthesis

3. The Dietary Fat Floor for Hormonal Health

Dietary fats are critical for testosterone synthesis, vitamin absorption (A, D, E, K), and cell membrane integrity. Never drop dietary fats below 0.3 g per pound of bodyweight (or <20% of total calories) for extended periods, as doing so crashes endocrine function and libido.

Healthy dietary fats extra virgin olive oil nuts and avocados — **Figure 3:** Prioritize monounsaturated and polyunsaturated fats from olive oil, avocados, whole eggs, and fatty fish. Hormone Health

4. Carbohydrates for Performance & Thyroid Function

Carbohydrates restock muscle glycogen and support active conversion of T4 thyroid hormone to active T3. In high-intensity resistance training, low-carb diets often reduce workout volume and lifting performance.

5. Worked Example: 180 lb Lifter (2,200 kcal Cutting Target)

• Protein (1.0 g/lb): 180 g × 4 kcal/g = 720 kcal (33%)
• Dietary Fat (0.35 g/lb): 63 g × 9 kcal/g = 567 kcal (26%)
• Remaining for Carbs: 2,200 − (720 + 567) = 913 kcal ÷ 4 kcal/g = 228 g Carbs (41%)
• Daily Targets: 180g Protein | 228g Carbs | 63g Fat = 2,200 kcal.

Editorial Transparency: WorldCalculator provides free mathematical calculators and objective educational guides. Some fitness apps, protein supplement brands, or meal delivery services may feature affiliate partnerships where we receive referral compensation at zero cost to you. Read our full Disclaimer & Affiliate Policy.

← Previous Guide Navy Body Fat Formula vs DEXA Scans Next Guide → Caloric Deficits & Metabolic Adaptation