Research vs Bro-science

Is Eating as Much as Possible Really the Best Way to Bulk?

Published: 2026-06-25

Written by: Shingo YoshizakiReviewed by: Tomonobu Someda

The idea that eating as much as possible during a bulk leads to maximum muscle growth is a long-standing gym belief. Yet research suggests that excessive calorie surpluses tend to add fat more than muscle. This article examines three key claims behind dirty bulking through the lens of current evidence.

Let the data settle it.

Round1

Does a massive calorie surplus (dirty bulk) maximize muscle growth?

What's said

ジム・フィットネス系YouTube、ボディビルディングフォーラム

During a bulk, the more you eat the more muscle you gain. Leaving calories on the table means leaving gains behind, so you should eat 3,000–5,000 kcal or more every day.

What research says

Muscle protein synthesis has a biological ceiling; once calorie surplus exceeds a certain threshold, additional muscle growth plateaus while excess energy is stored as fat.
A review by Phillips & Van Loon (2011) confirmed a similar plateau for protein intake and muscle synthesis.
Back-calculating from realistic muscle gain rates (roughly 0.5–1 kg/month for intermediate trainees), a daily surplus of around 200–500 kcal is generally considered sufficient.

Verdict

For healthy intermediate trainees, a surplus of roughly 200–500 kcal/day appears sufficient to capture most muscle growth benefits. Calories well beyond that tend to accumulate as fat rather than muscle. The claim that 'more eating equals more muscle' is not well supported.

Confidence:Mixed evidence

Protein supplementation augments resistance-training-induced gains in muscle mass and strength (meta-analysis)Dose-response relationship between weekly sets (training volume) and hypertrophy (systematic review)

Round2

Does carrying more body fat improve muscle-building efficiency?

What's said

旧来のオフシーズン理論、ボディビル文化

A bigger body produces more anabolic hormones, so carrying extra fat helps you build muscle faster. Just get big first, then cut later.

What research says

Higher body fat is associated with reduced insulin sensitivity and impaired anabolic signaling.
Accumulation of adipose tissue can increase inflammatory cytokines that may suppress muscle protein synthesis.
A review by Barakat et al.
(2020) on body recomposition notes a deterioration of the anabolic hormonal environment at higher body fat levels.
High-quality evidence supporting the idea that 'more fat means better muscle gains' is currently lacking.

Verdict

A high body fat percentage does not appear favorable for the anabolic hormonal environment. Beginners can build muscle regardless of fat levels, but intermediate-to-advanced trainees are likely better served by staying within a reasonable body fat range (roughly 15–20% for men).

Confidence:Weak evidence

Protein supplementation augments resistance-training-induced gains in muscle mass and strength (meta-analysis)

Round3

Lean bulk vs. dirty bulk: which approach yields more lean mass in the long run?

What's said

伝統的なオフ・オンシーズンサイクル論

A dirty bulk adds more total calories, so it must build more absolute muscle mass. After cutting, the same amount of muscle should remain either way.

What research says

Garthe et al.
(2013) found in elite athletes that rapid weight loss led to greater lean mass losses compared to slower weight loss.
Applying this to bulking: a prolonged cut following a dirty bulk risks losing muscle accumulated during the surplus phase.
Among researchers, the prevailing view is that cycling lean bulks (small-to-moderate surpluses) with moderate cuts yields comparable or superior net lean mass gains compared to dirty bulk plus extended cut cycles.

Verdict

In the long run, net lean mass gains are not significantly different between lean and dirty bulking. However, dirty bulking requires a longer subsequent cut, which increases the risk of muscle loss—making lean bulking the more efficient strategy overall for most trainees.

Confidence:Mixed evidence