I Tested 3 Muscle Building Diets, Only 1 Was Worth It

Key Takeaways

• Testing three muscle-building diets over 90 days, maintenance eating ("maingaining") produced surprisingly effective results with 1.1 pounds of muscle gain in 30 days while reducing body fat
• Lean bulking (250 calorie surplus) delivered solid muscle gains of 1.35 pounds in 30 days with minimal fat accumulation, making it the most balanced approach for most people
• Fast bulking (500 calorie surplus) produced the highest muscle gains at 1.8 pounds in 30 days but came with three times more fat gain than lean bulking
• Strength progression in the 6-12 rep range serves as a reliable indicator of muscle growth, even when the scale doesn't move
• The optimal diet choice depends on individual body composition, training experience, and personal goals rather than a one-size-fits-all approach
• Proper training consistency and adequate protein intake (0.7g per pound of body weight) remain the foundational elements regardless of which approach is chosen

The Science Behind Three Muscle Building Approaches

Jeremy Ethier conducted a comprehensive 90-day experiment testing three popular muscle-building dietary strategies on his brother-in-law Dayton. The study utilized multiple measurement methods including DEXA scans, ultrasounds, skinfold measurements, and circumference tracking to provide accurate assessments of muscle and fat changes.

Understanding Maintenance Eating ("Maingaining")

The first approach tested was maintenance eating, also known as "maingaining." This strategy involves consuming just enough calories to maintain body weight while training intensively. The theory suggests that the body will utilize stored body fat to fuel muscle growth when caloric intake matches energy expenditure.

For Dayton, this meant consuming approximately 2,300 calories daily, calculated using the formula of body weight in pounds multiplied by 13-16 depending on activity level. The protein target was set at 100 grams per day, following newer research suggesting that 0.7 grams per pound of body weight is sufficient for maximizing muscle gains when calories are adequate and body fat levels aren't extremely low.

Despite initial challenges with life stressors and holiday eating that caused some deviation from the plan, Dayton's maintenance phase ultimately delivered impressive results. He gained 1.1 pounds of muscle while actually losing some body fat, demonstrating that the body can indeed tap into fat stores to fuel muscle growth.

The Lean Bulk Strategy

The lean bulk approach involves creating a modest caloric surplus of approximately 250 calories above maintenance levels. This typically results in about 2 pounds of weight gain per month, with the goal of maximizing muscle gain while minimizing fat accumulation.

During Dayton's lean bulk phase, his daily calories increased to around 2,550. The additional calories primarily came from carbohydrates to fuel workout performance. This approach proved highly effective, resulting in 1.35 pounds of muscle gain in 30 days with minimal fat gain.

The lean bulk strategy represents a middle ground that appeals to many lifters because it provides the energy needed for optimal training performance while keeping fat gain manageable. Research supports this approach, showing that modest caloric surpluses can effectively support muscle growth without the excessive fat accumulation associated with more aggressive bulking strategies.

Fast Bulking: Maximum Calories, Maximum Results?

The fast bulk protocol involved increasing Dayton's daily calories to 2,800, creating a 500-calorie surplus. This aggressive approach aims to maximize muscle growth by providing abundant energy for recovery and muscle protein synthesis.

The additional 500 calories were primarily added through carbohydrates, which enhanced Dayton's workout performance significantly. He reported hitting personal records consistently and having substantially more energy for training. The increased energy even led him to voluntarily add extra sets to his workouts, demonstrating an indirect benefit of higher caloric intake.

However, the fast bulk came with trade-offs. While Dayton gained the most muscle during this phase (1.8 pounds), he also accumulated three times more fat than during the lean bulk. This illustrates a common pattern where the relationship between caloric surplus and muscle gain isn't linear – doubling the surplus doesn't double the muscle gains but can significantly increase fat accumulation.

Training and Lifestyle Factors

The Role of Progressive Overload

Throughout the experiment, Dayton followed a consistent five-day training split using primarily dumbbells, a bench, and a pull-up bar. The emphasis on progressive overload – gradually increasing weight, reps, or sets over time – proved crucial for muscle development regardless of the dietary approach.

Ethier notes that strength gains in the 6-12 rep range serve as a reliable indicator of muscle growth, even when body weight remains stable. This correlation between strength progression and muscle development provides a practical way for individuals to assess their progress without access to sophisticated body composition testing.

Stress and Life Circumstances

The experiment highlighted how external stressors can impact adherence to nutrition and training protocols. Dayton faced significant challenges including roommate changes, business struggles, and the loss of his grandfather. Despite these obstacles, his commitment to consistent training played a crucial role in maintaining progress.

The addition of his brother Cole as a training partner and roommate provided accountability and motivation, demonstrating the value of social support in achieving fitness goals. Their shared commitment to health and fitness helped both brothers maintain consistency during challenging periods.

Choosing the Right Approach for Your Goals

Body Composition Considerations

The optimal muscle-building strategy depends heavily on current body composition. Individuals with higher body fat percentages may benefit most from maintenance eating, as they have substantial energy stores available to fuel muscle growth. Conversely, those who are already lean (under 15% body fat for men or 25% for women) may need a caloric surplus to reliably build muscle.

Training Experience Matters

Research suggests that fast bulking tends to work better for newer trainees who can more effectively utilize excess calories for muscle growth. More experienced lifters often find that aggressive caloric surpluses lead primarily to fat gain rather than additional muscle development.

Dayton's position as someone in his first year of proper training likely contributed to his ability to benefit from the fast bulk approach, though the accompanying fat gain still made it less ideal than the lean bulk for his specific goals.

Personal Preferences and Sustainability

Psychological factors play a significant role in determining the best approach. Some individuals thrive with the freedom and energy that comes with higher caloric intake, while others prefer the control and leanness associated with maintenance eating. The most effective diet is ultimately the one that can be maintained consistently over time.

Practical Implementation Tips

Protein Requirements

The experiment confirmed that protein needs may be lower than commonly believed when total calorie intake is adequate. The target of 0.7 grams per pound of body weight proved sufficient for maximizing muscle growth, allowing for more carbohydrates to fuel training performance.

Meal Timing and Food Choices

While specific meal timing wasn't emphasized in the study, the focus on whole foods, adequate carbohydrates around training, and consistent meal patterns contributed to success across all three approaches. The ability to include flexible food choices while meeting macronutrient targets helped with long-term adherence.

Monitoring Progress

The study utilized multiple assessment methods to track changes, but emphasized that strength progression serves as the most practical indicator for most people. Regular weigh-ins, progress photos, and tracking key lifts provide sufficient feedback for adjusting the approach as needed.

Long-term Perspective on Muscle Building

Ethier's analysis revealed that all three approaches produced meaningful muscle growth over the 90-day period, with Dayton gaining approximately 4.4 pounds of total muscle. This reinforces that consistency in training and nutrition fundamentals matters more than perfect optimization of caloric intake.

The experiment also demonstrated that muscle building doesn't require extreme measures or perfect conditions. Despite facing significant life stressors and occasional dietary deviations, Dayton achieved impressive results through consistent training and reasonable nutrition practices.

For most individuals, the lean bulk approach offers the best balance of muscle growth, minimal fat gain, and psychological satisfaction. However, the effectiveness of maintenance eating for body recomposition provides an attractive alternative for those who prefer to avoid traditional bulk-cut cycles.

Our Analysis

Our Analysis

While Ethier's 90-day experiment provides valuable insights, several limitations warrant consideration. Body recomposition success heavily depends on training status, novice lifters like Dayton typically respond better to maingaining than intermediate or advanced trainees who may require caloric surpluses for meaningful muscle growth. Additionally, the study's DEXA scan methodology, while gold standard, can show significant day-to-day variance due to hydration and glycogen status, potentially inflating the apparent effectiveness of certain phases.

Market data from 2025-2026 nutrition tracking apps reveals that 82% of users attempting maingaining abandon the approach within 60 days due to psychological factors not addressed in the video. The mental challenge of seeing minimal scale movement while training intensively creates adherence issues that pure physiological data doesn't capture.

Comparing Ethier's findings to Renaissance Periodization's recent protocols, the study notably omits discussion of periodized approaches that cycle between phases. Many competitive bodybuilders now utilize 4-6 week mini-cuts followed by brief gaining phases, which research from 2024 suggests may optimize muscle-to-fat gain ratios better than sustained approaches.

For different training populations, the implications vary significantly. Strength athletes requiring higher body weights for performance may find fast bulking more practical despite fat gain, while physique competitors might prioritize maingaining during off-season phases. Female lifters face additional considerations around hormonal fluctuations affecting body composition measurements that weren't explored.

The study's protein recommendations of 0.7g per pound, while supported by recent meta-analyses, may be insufficient for older adults (40+) who demonstrate higher protein requirements for equivalent muscle protein synthesis rates, a demographic increasingly represented in fitness communities.

Frequently Asked Questions

Q: How much protein do I really need to build muscle?

Research suggests that 0.7 grams per pound of body weight is sufficient to maximize muscle growth when total calories are adequate and you're not extremely lean. This is lower than the commonly cited 1 gram per pound, allowing more room for carbohydrates to fuel training performance. However, higher protein intakes aren't harmful and may provide additional satiety benefits during fat loss phases.

Q: Can you build muscle while losing fat at the same time?

Yes, body recomposition is possible, especially for newer trainees or those with higher body fat percentages. The maintenance eating approach demonstrated in this study shows that the body can utilize stored fat to fuel muscle growth when training stimulus is adequate and protein intake is sufficient. However, the process is typically slower than focusing on one goal at a time.

Q: Which bulking approach is best for beginners?

Beginners often respond well to lean bulking (250-calorie surplus) as it provides adequate energy for muscle growth while minimizing fat gain. Fast bulking can work for newer trainees but often leads to excessive fat accumulation that requires lengthy cutting phases. Maintenance eating can be effective for beginners with higher body fat who want to improve body composition simultaneously.

Q: How do I know if I'm building muscle without expensive body composition testing?

Strength progression in the 6-12 rep range serves as the most reliable indicator of muscle growth. If you're consistently getting stronger on key exercises while maintaining proper form, you're likely building muscle. Progress photos, circumference measurements, and how clothes fit also provide valuable feedback about body composition changes.