Andarine (S4) – The Ultimate Guide to Fat Loss, Muscle Retention & Shredded Gains

Andarine (S4) – The Ultimate Guide to Fat Loss, Muscle Retention & Shredded Gains

Introduction

When it comes to SARMs that actually deliver clean, dry muscle and serious fat loss, Andarine (S4) stands out as a favorite among performance enthusiasts. Often referred to as “the cutting SARM,” S4 offers a powerful balance of strength gains, body recomposition, and lean muscle preservation — all without the bloating or estrogenic side effects of anabolic steroids.

But it’s not all sunshine and shredded six-packs — S4 also has a controversial reputation due to a very specific side effect: changes in night vision.

In this deep-dive article, we’ll break down everything you need to know about Andarine — from how it works, what the science says, dosing protocols, stacking advice, side effects, and how to use it safely.

What is Andarine (S4)?

Andarine, also known as S4 or GTX-007, is a Selective Androgen Receptor Modulator (SARM) originally developed by GTx Inc. for clinical use in treating muscle wasting, osteoporosis, and benign prostatic hypertrophy.

It was designed to mimic the muscle-building effects of anabolic steroids — without the harsh androgenic impact on the prostate, hairline, or internal organs.

While it was never approved for pharmaceutical use, it quickly gained popularity as a research chemical among athletes, bodybuilders, and physique competitors.

How Does S4 Work? (Mechanism of Action)

Andarine binds selectively to androgen receptors in muscle and bone tissue, stimulating anabolic activity similar to testosterone — but without converting to estrogen or DHT.

Here’s what that means in practice:

• Increased lean muscle retention (especially in a caloric deficit)

• Enhanced fat oxidation

• Improved strength and endurance

• Bone support and density improvement

However, S4 also binds weakly to receptors in the eyes, leading to temporary visual side effects in some users — such as yellow tint or difficulty adjusting to darkness.

Clinical Research & Scientific Evidence

While no large-scale human clinical trials were completed, S4 was studied extensively in preclinical and animal models:

🧪 GTx Inc. Studies

• Animal trials showed significant improvements in lean muscle mass, bone mineral density, and muscle function in models of muscle-wasting disease.

🧪 Gao et al. (2005)

• Published in Current Opinion in Clinical Nutrition & Metabolic Care, the paper discussed S4’s potential to provide anabolic support without androgenic side effects, especially in the prostate.

📚 Reference: Gao W, Dalton JT. “Selective Androgen Receptor Modulators (SARMs) as Function Promoting Therapies.” Curr Opin Clin Nutr Metab Care. 2005;8(6):659-64.

Real-World Experiences & Anecdotal Reports

On platforms like Reddit, Bodybuilding.com, and SARMs-focused Facebook groups, S4 is praised for:

✅ Pros:

• Noticeable strength and muscle gains in 2–3 weeks

• Dry, vascular, defined look with little to no water retention

• Works well in cutting or recomposition stacks

• Minimal to no aromatization

❌ Cons:

• Vision side effects in up to 50% of users

• Testosterone suppression at higher doses or longer cycles

• Mild lethargy if diet or recovery is lacking

Ideal Uses: Cutting, Recomp & Fat Loss

If you're trying to:

• Drop body fat while holding onto lean muscle

• Recomp your physique (lose fat, gain muscle at the same time)

• Get "photo-ready" for a shoot or summer

S4 is ideal for:

• Cutting cycles

• Stacking with Cardarine or Ostarine

• Mid-to-advanced users who understand PCT and side effect management

Recommended Dosing Protocols

🕒 Cycle Duration: 6–8 weeks
🧪 Half-Life: ~4 hours — best taken in split doses (AM + PM)

Stacking Recommendations

🔥 Cutting Stack

• S4 + Cardarine (GW-501516)

  • Boosts fat oxidation, preserves muscle

💪 Recomp Stack

• S4 + Ostarine (MK-2866) + MK-677

  • Build lean muscle while burning fat

⚠️ Support Supplements

• Lutein + Zeaxanthin – for eye support

• NAC or TUDCA – for liver support

• Natural test boosters – during PCT phase

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Benefits You Can Expect

Side Effects & How to Manage Them

⚠️ Common Side Effects:

• Vision changes (yellow tint, night blindness)

• Testosterone suppression

• Insomnia, mood changes

✅ Solutions:

• Lower dose (25 mg/day)

• Shorter cycle (4–6 weeks)

• Take eye support (Lutein)

• Always follow with PCT

Post-Cycle Therapy (PCT)

Andarine does cause suppression, so PCT is highly recommended, especially at higher doses.

🧬 Standard PCT Protocol:

• Clomid: 50/25/25/25 mg (4 weeks)

• OR

• Nolvadex: 20/20/10/10 mg (4 weeks)

Support with:

• Zinc, Vitamin D, Ashwagandha, Tongkat Ali

• Proper sleep, whole food diet, and deload training week

Legality and Where to Buy

• U.S.: Legal to purchase as a research chemical only

• Europe: Banned for human consumption in most countries

• Athletics: Banned by WADA and most competitive organizations

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Final Thoughts: Is S4 Worth It?

Andarine is one of the most effective SARMs for cutting, shredding fat, and maintaining muscle mass — but it’s not without its risks.

Pros:

• Fast fat loss

• Strength gains

• No bloat or estrogen conversion

Cons:

• Vision-related sides

• Suppression of natural testosterone

• Requires proper cycle planning and PCT

If you’re an intermediate to advanced lifter, familiar with SARMs and committed to doing it safely — S4 might be the edge you’ve been looking for.

Ready to Run Your First S4 Cycle?

🧪 Get your research-grade Andarine (S4), stacks, and cycle support here:
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