Jeremy Ethier

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

The video documents a 90‑day experiment comparing three popular muscle‑building diets—maintenance, lean bulk and fast bulk—on the creator’s brother‑in‑law Dayton. Using DEXA scans, ultrasounds, skinfolds and circumference measurements, the team tracked changes in lean mass, fat, and strength while keeping workouts constant. During the lean‑bulk phase (maintenance calories + ~250), Dayton added an estimated 1.35 lb of muscle in 30 days, outperforming the 2.4 lb average from short‑term studies. The subsequent fast‑bulk phase (maintenance + 500 cal) produced 1.8 lb of muscle but also three times more fat, confirming that excess calories boost strength and size but risk unwanted adipose tissue, especially in more experienced lifters. Key moments include Dayton’s pull‑up strength doubling, the creator’s observation that “fast bulking works best for untrained lifters,” and personal anecdotes about dirty bulks turning “fluffy.” The experiment also highlighted a protein target of 0.7 g per pound body weight, freeing calories for carbs to fuel workouts, and demonstrated how consistent strength gains can signal muscle growth even when the scale is static. The findings suggest that novice lifters benefit from modest calorie surpluses, while aggressive bulks should be reserved for those with sufficient training experience or body‑fat reserves. For fitness coaches and app developers, the data reinforce the value of personalized, data‑driven nutrition plans and the marketing power of documented, real‑world results.