[Experiment] Prompts for Muscular Male Bodies | 9 Conditions, 27 Images

Conclusion First

• Even the control (no body type specified), the gym + tank top context already produces a reasonably muscular body type
• All 8 muscle descriptors produced a clear increase in muscle mass compared to the control
• The largest muscle mass increase was from heavyweight — shoulders, arms, and thighs all got thicker, with an overall volume increase across the whole body
• bodybuilder also showed significant muscle mass increase, but without the full-body width expansion of heavyweight
• muscular, buff, ripped, jacked, and bulky all increase muscle mass, but the differences between conditions are small — the variation between seeds is larger than the variation between conditions
• lean muscle is the most restrained condition, closest to the control
• Asian male appearance was maintained in all conditions — no racial changes observed

Experimental Design

Base Prompt

Using 1boy, 32yo japanese actor to observe muscle mass changes in male subjects.

A00: control

seed 1	seed 2	seed 3

Observation: Baseline without body type specification. All 3 images show East Asian males in tank top and shorts. Seed 1: navy tank top with gray shorts, shoulders and upper arms show some muscle. Seed 2: gray tank top with white basketball pants, slightly lean. Seed 3: white tank top with navy basketball pants, the slimmest of the three with thinner arms. Overall impression: “an ordinary-build man at the gym.”

A01: muscular

seed 1	seed 2	seed 3

Observation: All 3 images show clearly increased muscle mass in the arms and shoulders compared to the control. Seed 1: larger deltoid and bicep volume than control, with thicker quadriceps. Seed 2: gray tank top, broader chest and shoulders than control. Seed 3: white tank top, thicker arms and chest than the same seed in control. Clothing (tank top + shorts) unchanged. Asian appearance maintained.

A02: buff

seed 1	seed 2	seed 3

Observation: Similar muscle mass increase to muscular. Seed 1: navy tank top, thicker upper arms and deltoids than control. Seed 2: gray tank top, broader shoulders and thicker thighs. Seed 3: white tank top, no clear difference from muscular seed 3. No consistent difference between buff and muscular — variations fall within seed-to-seed variance. Asian appearance maintained.

A03: ripped

seed 1	seed 2	seed 3

Observation: Similar muscle mass to muscular and buff. “Ripped” normally implies low body fat with visible muscle definition, but the tank top prevents observation of ab separation. All images show notable muscle mass in shoulders and arms. No noticeable difference from muscular or buff. Asian appearance maintained.

A04: bodybuilder

seed 1	seed 2	seed 3

Observation: More muscle mass than muscular/buff/ripped. Seed 1: navy tank top, clearly thicker deltoids, biceps, and quadriceps than previous conditions — shoulders are broad enough that the arms bulge out from the tank top sleeve. Seed 2: gray tank top with similarly thick shoulders and chest. Seed 3: white tank top with noticeably wider upper body than control. However, doesn’t reach the full-body volume increase of heavyweight (described later). Asian appearance maintained.

A05: lean muscle

seed 1	seed 2	seed 3

Observation: The most restrained muscle mass among the muscle descriptors. Seed 1: navy tank top, upper arms show more muscle than control but not as thick as muscular. Seed 2: gray tank top, body type close to control. Seed 3: white tank top, arms are slim with little difference from control seed 3. “Lean” may be directing toward a toned, low-body-fat physique, prioritizing muscle “quality” over “quantity.” Asian appearance maintained.

A06: bulky

seed 1	seed 2	seed 3

Observation: Similar muscle mass to muscular/buff/ripped. Despite “bulky” implying increased body width, no consistent difference in body width or depth compared to muscular was observed. Asian appearance maintained.

A07: jacked

seed 1	seed 2	seed 3

Observation: Similar muscle mass to muscular/buff/ripped. No jacked-specific effect confirmed — output is similar level to muscular and buff. Asian appearance maintained.

A08: heavyweight

seed 1	seed 2	seed 3

Observation: The largest body type change across all conditions. Seed 1: navy tank top, clearly thicker shoulders, upper arms, and thighs than any other condition — an obvious overall volume increase. The face also becomes rounder, showing an overall size-up including body fat. Seed 2: gray tank top, similarly very broad shoulders with notably thick arms and legs. Seed 3: white tank top, large body type across all seeds. While bodybuilder emphasizes “muscle development,” heavyweight trends toward “full-body size increase.” Asian appearance is maintained, though the face tends to become somewhat rounder.

Summary

Muscle Mass Ranking (most → least)

1. heavyweight — maximum overall volume. Body width and depth increase alongside muscle
2. bodybuilder — prominent muscle development, but not as much full-body size increase as heavyweight
3. muscular / buff / ripped / bulky / jacked — differences between these are smaller than seed-to-seed variance; effectively equivalent
4. lean muscle — restrained muscle mass increase; closest to the control
5. control (no body type specified) — the gym + tank top context produces some muscularity by default

Side Effects

• Racial changes: Asian male appearance maintained in all conditions. No racial changes from muscle descriptors observed
• Clothing changes: Tank top + shorts maintained in all conditions. No clothing impact
• Facial changes: Only heavyweight showed a tendency toward a rounder face. No facial impact in other conditions

Usage Guide

buff, ripped, bulky, and jacked produce similar effects to muscular — choosing the single-token muscular is the most efficient option.

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