Understanding How much fat do you need when bulking?

October 20, 2025 •

3 min read

One gram of fat contains 9 calories, more than double the energy density of protein and carbohydrates, making it a critical, energy-dense nutrient for anyone in a calorie surplus. For this reason, it's essential to understand exactly how much fat do you need when bulking to fuel muscle growth effectively without gaining excessive body fat.

Quick Summary

Fat is crucial for bulking, supporting hormone production and providing energy, with typical recommendations ranging from 20–35% of total calories. The ideal intake depends on your overall caloric goal and individual metabolic needs, and focusing on healthy, unsaturated fats is key to optimizing muscle growth and hormonal health.

Key Points

Target Fat Range: Aim for 20-35% of your total daily calories from fat during your bulk to support energy and hormone function.
Hormonal Support: Adequate fat intake is essential for maintaining optimal testosterone levels, a critical hormone for muscle growth.
Energy Source: Fats provide a calorie-dense and sustained energy source, especially important for longer, high-volume training sessions.
Healthy Choices Matter: Prioritize healthy unsaturated fats from sources like avocados, nuts, and oily fish while limiting trans fats.
Avoid Extremes: Severely restricting fat can lead to hormonal imbalances, nutrient deficiencies, and hinder muscle gains.
Calculation is Key: Determine your fat intake based on your total daily caloric needs and goals, using it to fill the remaining calories after setting protein and carb targets.

The Importance of Dietary Fat for Muscle Growth

Dietary fats are crucial for optimizing muscle development and overall bodily function during a bulk. Adequate intake supports key biological processes impacting muscle growth.

Hormonal Function and Anabolic Drive

Dietary fats are essential for steroid hormone synthesis, including testosterone, which promotes muscle protein synthesis. Low-fat diets can reduce testosterone levels, hindering muscle growth. Sufficient healthy fats help maintain optimal hormonal function.

A Sustained Energy Source

During intense training, fat serves as a concentrated, long-lasting energy source, especially once carbohydrate stores are low. Its calorie density (9 calories per gram) is beneficial for maintaining a caloric surplus. This supports performance and prevents fatigue, particularly in endurance aspects of strength training.

Nutrient Absorption and Cellular Health

Fat is necessary for the absorption of fat-soluble vitamins (A, D, E, K), which are vital for immune health, bone health, and muscle repair. Fatty acids are also key structural components of cell membranes, including muscle cells, supporting optimal function and integrity for growth and recovery.

How to Calculate Your Fat Intake for Bulking

Experts generally recommend that fats constitute 20% to 35% of your total daily calorie intake when bulking. The specific amount can be adjusted based on individual factors.

To calculate your needs:

Calculate your Total Daily Energy Expenditure (TDEE): Use an online calculator to estimate the calories needed to maintain your weight.
Add a caloric surplus: For a lean bulk, add 200–500 calories to your TDEE.
Determine protein and carbohydrate needs: A common approach is to set protein (0.8–1 gram per pound of body weight) and carbohydrate goals (45–60% of total calories) first.
Fill the remaining calories with fat: The remaining calories should come from fat, ideally within the 20–35% range.

For example, on a 3,000-calorie bulking diet, 25% fat equates to 750 calories from fat, or about 83 grams (750 / 9 = 83g).

High-Carb vs. Higher-Fat: A Comparison for Bulking

Both carbohydrates and fats provide essential energy for bulking, but they serve different purposes. The choice of which to prioritize depends on training style, metabolic response, and personal preference. Below is a comparison of key differences:


Feature	High-Carbohydrate Strategy (50-60% carbs, 20-30% fat)	Higher-Fat Strategy (30-35% fat, 40-50% carbs)
Primary Energy Source	Glycogen from carbohydrates, preferred for intense, anaerobic training.	Stores body fat and moderate carbs, used for prolonged, steady-state energy.
Training Performance	Supports high-intensity, high-volume workouts by rapidly replenishing glycogen stores.	Can provide sustained energy for longer sessions, but may hinder explosive movements.
Hormonal Support	Can improve insulin sensitivity and reduce cortisol, aiding recovery.	Directly supports testosterone production, vital for muscle protein synthesis.
Body Composition	Often results in a 'leaner' bulk with less fat accumulation if calories are tightly controlled.	Some individuals may experience more fat gain, though it provides more hormonal benefits.
Feeling of Fullness	Carbs and protein are generally less calorie-dense, which may lead to feeling less full per calorie.	Fat is highly satiating, which can help manage overall hunger and prevent overeating.
Metabolic Response	Optimizes insulin response for nutrient partitioning towards muscle cells.	Dependent on individual metabolic needs, with some showing higher fat storage.

Choosing Your Healthy Fat Sources

For optimal health and muscle growth, focus on unsaturated fats (monounsaturated and polyunsaturated) and moderate saturated fat, while avoiding trans fats.

Monounsaturated Fats: Found in avocados, olive oil, nuts, and seeds. They support testosterone production and heart health.
Polyunsaturated Fats (Omega-3 and Omega-6): Omega-3s from fatty fish, flaxseeds, and walnuts are beneficial for reducing inflammation and enhancing muscle recovery. Omega-6s are in vegetable oils and eggs.
Sources of Saturated Fat: Moderate amounts from whole eggs, red meat, and dairy are necessary for testosterone synthesis.

Conclusion

Fat is a vital macronutrient for muscle building, providing dense energy, supporting hormone production (like testosterone), and aiding in the absorption of essential fat-soluble vitamins. Aiming for 20-35% of total calories from fat is a general guideline, but individual needs vary. Prioritizing healthy unsaturated fats from sources like avocados, nuts, and fatty fish helps optimize muscle growth with minimal unwanted fat gain. A balanced intake of protein, carbohydrates, and fat is key for sustainable, healthy muscle gains. For further guidance, explore resources like the ISSA blog for nutrition coaches.

Frequently Asked Questions

A healthy fat percentage for bulking generally falls within 20% to 35% of your total daily calories. This range provides enough fat to support hormone production and energy needs without being overly excessive.

First, determine your total daily calorie needs for bulking. Then, calculate your protein and carbohydrate requirements. The remaining calories can be allocated to fat. For example, if you need 3,000 calories and dedicate 25% to fat, you would consume 83 grams of fat per day (3,000 * 0.25 = 750 calories; 750 / 9 = 83g).

Focus on healthy, unsaturated fats, such as monounsaturated fats from avocados and olive oil, and polyunsaturated fats (especially omega-3s) from fatty fish, flaxseeds, and walnuts. These are beneficial for hormone health and reducing inflammation.

Yes, a diet that is too low in fat can have negative consequences for muscle growth. It can disrupt hormonal balance, potentially lowering testosterone levels, and may cause deficiencies in fat-soluble vitamins, hampering overall progress.

While it's important to keep saturated fat in moderation, some intake is necessary for optimal testosterone production. Saturated fats are found in animal products like red meat and eggs, but should not be the dominant source of fat in your diet.

Both are crucial energy sources, but serve different functions. Carbohydrates are the body's preferred fuel for high-intensity exercise and rapidly replenish glycogen stores. Fats provide a more sustained, long-term energy supply. For maximizing training performance, carbs are generally prioritized for gym fuel, while fat fills out the remaining calorie needs.

Yes, it is completely normal to gain some body fat during a bulk, as achieving a caloric surplus without gaining any fat is difficult. The goal is a 'lean bulk,' where muscle gain outpaces fat gain. Monitoring your body composition and keeping your surplus moderate can help minimize excessive fat accumulation.

Yes, trans fats should be avoided as much as possible. They are industrially hydrogenated fats that offer no health benefits and are linked to negative health outcomes, including heart disease.