Peptides Explained: The Science Behind Fat Loss, Muscle Growth, and Total Body Optimization

Let me start by saying, if you do not have diet dialed in, sleep dialed in, stress dialed in; do not waste your money on these peptides. These protocols cannot and will never cover up a bad diet; or even an 80/20 diet. What I am trying to say is, focus on your hormones (consider HRT which will help you way more than peptides), sleep, diet and exercise before investing your hard earned money on peptides.

Peptides are one of the most misunderstood categories in health right now. Some are legitimate, well-studied medicines. Some are still investigational. Others are sold in “optimization” circles long before good human evidence exists. And one item on my list—NAD+—is not actually a peptide at all; it is a coenzyme involved in cellular energy metabolism.

First, what peptides actually are

Peptides are short chains of amino acids that act like biological messengers. Some stimulate receptors that control appetite and blood sugar. Others influence growth-hormone signaling, wound-healing pathways, or immune regulation. But peptide is a structural category, not a promise of effectiveness. The fact that two compounds are both peptides does not mean they have similar evidence, benefits, or risks.

GHK-Cu: probably more interesting for skin than for body optimization

This peptide is my favorite. I have gotten so many compliments on my skin and I know it is because of GHK-cu. I not only use the injection form of GHK-cu, I also use topical forms (found HERE) as well as a topical hair product after I microneedle my scalp.

GHK-Cu (glycyl-L-histidyl-L-lysine-copper) is a naturally occurring copper peptide known for potent anti-aging, skin regeneration, and anti-inflammatory properties. It enhances skin firmness, boosts collagen and elastin production, accelerates wound healing, reduces wrinkles, and improves hair growth.

Key Benefits of GHK-Cu:

Skin Rejuvenation and Anti-Aging:
- Boosts Collagen/Elastin: Stimulates collagen and elastin production, increasing skin firmness and elasticity while reducing fine lines and wrinkles.
- Improves Texture: Smooths rough skin and reduces photodamage, hyperpigmentation, and skin spots.
- Tightens Skin: Reverses age-related skin thinning by promoting structural protein repair.
Wound Healing and Tissue Repair:
- Speeds Repair: Promotes faster wound healing and tissue regeneration.
- Reduces Inflammation: Acts as a potent anti-inflammatory, lowering oxidative stress and reducing damage from free radicals.
- Skin Barrier Repair: Repairs the skin’s protective barrier and acts as an antioxidant.
Hair Health:
- Increases Growth: Encourages hair growth and increases hair follicle size, resulting in thicker, fuller hair.
- Reduces Shedding: Strengthens hair follicles and reduces hair shedding.
Other Potential Benefits:
- Brain Health: Preliminary evidence suggests potential cognitive protection by reducing inflammation in the brain.
- Supports Longevity: Helps restore “replicative vitality” to cells, particularly beneficial for fibroblasts.

GHK-Cu is often applied topically in skincare or used in restorative therapies to improve skin quality and combat visible signs of aging. Results are typically seen over several weeks to months, with reported improvements in skin density and elasticity.

Click HERE to find injectable GHK-cu

As you can see in the photo below, I LOVE GHK-cu! I love it topically on my skin as well as for my hair growth.

Click HERE to find topical hair growth GHK-cu as well as skincare and oral capsules.

MOTS-c: fascinating biology, thin human evidence

This peptide is also very fascinating and has been a favorite amongst myself and other peptide lovers. MOTS-c is one of the most interesting compounds on my list scientifically.

MOTS-c is a mitochondrial-derived peptide that acts as a potent metabolic regulator, offering benefits such as improved insulin sensitivity, enhanced fat metabolism, increased cellular energy (ATP) production, and improved physical endurance. It helps combat age-related metabolic decline by promoting AMPK activation, reducing inflammation, and supporting cardiovascular health.

Key Benefits of MOTS-c

Improved Metabolic Function: MOTS-c acts on the mitochondrial “control center” to optimize fuel usage, increase glucose uptake in skeletal muscle, and improve insulin sensitivity. It is particularly noted for reducing obesity and insulin resistance caused by high-fat diets.
Enhanced Energy and Endurance: By increasing ATP production and regulating cellular energy, MOTS-c can lead to higher physical energy levels, improved exercise capacity, and faster recovery times.
Weight Loss and Fat Loss: It helps promote weight management by reducing body weight, increasing fatty acid metabolism, and supporting the breakdown of fat tissue while protecting lean muscle mass.
Anti-Aging and Longevity: MOTS-c acts as a cellular communicator that preserves mitochondrial function, reduces oxidative damage, and helps maintain metabolic homeostasis during aging.
Reduced Inflammation and Improved Flexibility: It modulates inflammation and helps the body adapt to metabolic stress, enhancing overall metabolic flexibility.
Bone Health: Research suggests MOTS-c plays a role in bone remodeling, promoting the formation of osteoblasts.

Key Physiological Mechanisms

AMPK Activation: Known as the “metabolic master switch,” activating AMPK helps increase glucose uptake, increase fat oxidation, and promote mitochondrial biogenesis.
Folate-Purine Pathway: It acts within this pathway to improve metabolic flexibility.

BIGGEST MOTs-c Mistake

MOTS-c is typically administered as a subcutaneous injection, often used to improve metabolic health, support weight loss, and boost athletic performance but the biggest mistake I see people do when using this powerful peptide, is that they use smaller doses. Most vials of MOTs-c will be 5 or 10mg. Once you reconstitute this vial, it degrades fast. To get the benefits from the vial, you need to inject the entire contents soon after reconstituting. Doing a cycle of 10 to 20 days once or twice a year has profound benefits for the mitochondria as well as insulin resistance.

SS-31: Mitochondria Repair

Another favorite peptide of mine due to the mitochondria enhancements!

SS-31 (Elamipretide) is a mitochondria-targeted peptide that repairs damaged mitochondria, reduces oxidative stress, and boosts ATP production. Key benefits include enhanced physical endurance, improved cognitive function, reduced inflammation, and potential reversal of age-related tissue decline in the heart, kidneys, and muscles.

Key Health Benefits of SS-31

Mitochondrial Repair & Energy: SS-31 restores mitochondrial structure and function, leading to increased ATP production and cellular energy.
Anti-Aging and Muscle Function: It reverses age-related mitochondrial damage, increasing fatigue resistance and muscle mass in older models.
Cardiovascular Protection: Studies show SS-31 reduces ischemia-reperfusion injury, reduces cardiac hypertrophy, and improves heart function (LVEF).
Neuroprotection: It improves cognitive function by reducing oxidative damage and promoting synaptic health in the brain.
Kidney and Metabolic Health: SS-31 has shown potential to reduce glomerulosclerosis in kidneys and improve metabolic markers in diabetes.
Improved Recovery: It can improve exercise tolerance and reduce fatigue

EPITALON: Longevity Peptide

This has been another favorite peptide of mine and I personally have done 5 rounds of this in past years.

Epitalon (or Epithalon) is a synthetic tetrapeptide designed to mimic the natural hormone epithalamin, produced by the pineal gland. It is primarily known for its potent anti-aging effects, including lengthening telomeres, increasing melatonin synthesis by up to 160%, stimulating cellular regeneration, and acting as a strong antioxidant, which can improve sleep, boost immunity, and increase lifespan.

Key researched benefits of Epitalon include:

Telomere Extension: Epitalon activates the enzyme telomerase, which lengthens telomeres (the protective caps on chromosomes), thus slowing cellular aging and increasing cell lifespan.
Improved Sleep and Circadian Regulation: It regulates the pineal gland to increase natural melatonin production, significantly improving sleep quality, particularly in older adults.
Anti-Aging and Longevity: Animal studies have shown that Epitalon can increase lifespans by 10% to 25% by reducing age-related chromosomal damage and supporting overall vitality.
Immune System Support: It increases the production of interferon and interleukins, improving immune function and helping the body fight off diseases.
Antioxidant Function: Epitalon acts as a potent antioxidant, neutralizing free radicals and reducing lipid oxidation, which protects cells from damage.
Cancer Prevention and Tumor Inhibition: Research suggests it can reduce tumor development risk and inhibit the growth of certain cancers (e.g., breast, colorectal) by normalizing gene expression.
Retinoprotection: Studies indicate it helps restore retinal integrity, potentially protecting against age-related macular degeneration (AMD).
Skin Health: It promotes increased skin elasticity and hydration, contributing to improved skin tone and texture.

As far as dosing, this one needs a professional to help you and I would be honored to help!

GLPs for Fat Loss: semaglutide, tirzepatide, and retatrutide

Semaglutide = GLP-1
Tirzepatide = GIP + GLP-1
Retatrutide = GIP + GLP-1 + glucagon

Fat loss

Semaglutide has the strongest long-term real-world footing among the three because it is established and approved. In STEP 1, semaglutide 2.4 mg produced 14.9% mean weight loss at 68 weeks versus 2.4% with placebo.

Tirzepatide is stronger for weight loss. In SURMOUNT-1, mean weight loss at 72 weeks was 15.0% with 5 mg, 19.5% with 10 mg, and 20.9% with 15 mg, versus 3.1% with placebo.

Retatrutide looks strongest so far, but it is still investigational. In the phase 2 obesity trial, retatrutide produced substantial weight loss, with Lilly reporting up to 24.2% mean weight reduction at 48 weeks.

Muscle loss / lean-mass loss

MUSCLE AND STRENGTH ARE THE KEY TO LONGEVITY! So be careful if you venture into this space without a qualified nutritionist like myself to guide you.

This is where the conversation gets more nuanced.

With semaglutide, body-composition analyses show that absolute lean mass does go down. A 2024 systematic review concluded semaglutide appears to drive weight loss though notable reductions in lean mass do occur.

With tirzepatide, the 2025 SURMOUNT-1 DXA substudy found that tirzepatide significantly reduced body weight, fat mass, and lean mass. Recent reviews describe the lean-mass share of weight lost with tirzepatide as roughly in the same general range seen with other major obesity treatments, not uniquely catastrophic, but still clinically relevant.

With retatrutide, the 2025 body-composition substudy found that it improved body composition through greater fat-mass reduction versus lean-mass loss, and the authors specifically stated that the proportion of lean-mass loss to total weight loss was similar to other obesity treatments, despite the greater overall weight loss. In that substudy, the highest-dose group showed up to 26.1% reduction in total fat mass and up to 6.5 kg loss in lean mass over 36 weeks in adults with type 2 diabetes.

Losing lean mass should never be the goal. This is detrimental when it comes to blood sugar management and overall health.

Best practical summary

Drug	Mechanism	Average fat-loss strength	Lean-mass loss concern	Main benefit	Main downside
Semaglutide	GLP-1	Strong	Moderate	Best-established option	Less weight loss than tirzepatide/retatrutide
Tirzepatide	GIP + GLP-1	Very strong	Moderate	More weight loss than semaglutide	GI side effects, lean mass loss
Retatrutide	GIP + GLP-1 + glucagon	Strongest so far	Moderate	Biggest fat-loss signal	Still investigational

My practical read on GLP-1

If the goal is maximum fat-loss potential, retatrutide looks most promising, but YOU STILL MUST DO THE WORK AND CHANGE YOUR HABITS!

For muscle preservation, none of these drugs do the work for you. The bigger the weight loss, the more important it is to pair the medication with adequate protein, resistance training, and not letting appetite suppression drive chronically low protein intake. The evidence so far suggests they preferentially reduce fat, but not fat alone.

Working with a nutritionist such as myself to design a specific diet program and strength training regime is going to help you maintain your muscle as you burn fat, but remember, if you take these drugs without changing your diet, you can lose up to 50% muscle as you lose fat which means you have a higher risk of type 2 diabetes and insulin resistance. You do not want to reduce your muscle mass!

Tesamorelin: reduce viseral fat

Tesamorelin is a synthetic growth hormone-releasing hormone (GHRH) analogue primarily used to reduce visceral (abdominal) fat in HIV-infected patients with lipodystrophy. It works by increasing IGF-1 levels, offering benefits such as reduced belly fat, improved lipid profiles, increased lean muscle mass, improved cognitive function, and enhanced energy levels.

Key Benefits of Tesamorelin:

Reduced Visceral Fat: It is highly effective at targeting and reducing visceral adipose tissue (deep belly fat surrounding internal organs), with clinical trials showing approximately 15% reduction over 6 months.
Improved Metabolic Markers: It reduces triglycerides and improves overall cholesterol profiles, supporting cardiovascular health.
Increased Lean Muscle Mass: It helps preserve or increase lean muscle mass and strength while reducing fat.
Enhanced Body Composition: By lowering fat and supporting muscle, it improves overall body contouring and reduces lipohypertrophy (fat accumulation).
Improved Cognitive Function: Studies suggest it may enhance cognitive function and improve memory in adults with early signs of dementia.
Increased Energy and Recovery: Users often report higher energy levels, better sleep quality, and improved recovery after workouts

Published studies report that tesamorelin reduces visceral adipose tissue by roughly 15% to 20% over 6 to 12 months in HIV-associated lipodystrophy, including one trial showing a 15.2% decrease in visceral adipose tissue versus a 5.0% increase with placebo.

That makes tesamorelin useful to understand as a precision tool, not a general “fat-loss peptide.” It can change where fat is stored in a specific disease setting without being a broad anti-obesity medication.

CJC-1295 and ipamorelin: the “GH secretagogue”

CJC-1295 and Ipamorelin, often combined in peptide therapy, boost natural growth hormone (GH) levels, offering benefits like increased lean muscle mass, enhanced fat loss, improved sleep quality, faster recovery, and anti-aging effects such as better skin tone. This combination is popular for body recomposition and increasing energy levels.

First off if you are having low human growth hormone signs, there are many free ways to increase human growth hormone such as prioritizing sleep, not eating 3 hours before bedtime, strength training, sauna (or hot baths). As well as natural supplements such as GABA and Alpha GPC before strength training also increase HGH.

Key Benefits of CJC-1295/Ipamorelin Therapy:

Enhanced Body Composition: Promotes the growth of lean muscle tissue and helps burn stubborn fat by increasing metabolic rate.
Accelerated Recovery: Improves recovery times from workouts and injuries by supporting collagen production and reducing inflammation in muscles and joints.
Improved Sleep: By optimizing growth hormone release, users often experience deeper, more restorative REM sleep.
Anti-Aging and Skin Health: Boosts collagen production, improving skin elasticity, hair strength, and overall skin tone.
Increased Energy and Focus: Users commonly report higher energy levels, improved mental clarity, and better mood.
Increased Libido: The increased hormone levels may lead to an improved sex drive.

Key Differences and Administration:

Mechanism: CJC-1295 works as a Growth Hormone Releasing Hormone (GHRH) analog, while Ipamorelin is a GH secretagogue that mimics ghrelin, together providing a synergistic, stronger release of growth hormone.
Administration: Typically administered via subcutaneous injection, usually at night on an empty stomach to maximize natural, deep-sleep GH peaks. Consuming any food around the injection will interfere with aborption due to insulin.
Timeline: While sleep improvements may appear in 1–2 weeks, noticeable changes in muscle mass and fat reduction usually take 6–12 weeks of consistent use

Thymosin alpha 1: more of an immune peptide than an optimization peptide

This is a peptide I love to use before traveling to help my immune system stay strong.

Thymosin alpha-1 is a synthetic peptide that restores and enhances immune function, primarily used to treat chronic viral infections, improve vaccine response, and modulate autoimmune conditions. It supports T-cell production, acts as an adjuvant in cancer therapy, reduces inflammation, and aids in repairing tissue damage from severe infections.

Key benefits of Thymosin Alpha-1 include:

Immune System Modulation: Talpha1 acts as an immune “master controller,” bringing the immune system into balance by enhancing T-cell activity while curbing excessive inflammatory responses.
Chronic & Acute Infection Support: It is used to manage chronic infections like hepatitis B/C, Lyme disease, Epstein-Barr virus (EBV), and HIV, as well as acute infections like influenza and COVID-19.
Cancer Therapy Adjunct: Studies suggest it can enhance the efficacy of chemotherapy and radiation while reducing immune suppression caused by these treatments.
Anti-Aging (Immunosenescence): It helps counteract the decline of immune function that occurs with age by stimulating thymus activity.
Autoimmune Regulation: It helps balance the immune system, potentially supporting individuals with autoimmune conditions like Hashimoto’s thyroiditis, psoriasis, or multiple sclerosis.
Reduced Mortality in Sepsis: Research indicates it can lower mortality rates in severe sepsis patients.

Administration and Common Uses
Thymosin alpha-1 is typically administered via subcutaneous injection, often 2-3 times weekly. It is often sought for improved energy, faster recovery from sickness, and enhanced immune resilience. It is generally considered to have a low risk of side effects.

BPC-157: Body Protective Compound

BPC-157 (Body Protection Compound-157) is a synthetic peptide known for accelerating the healing of muscles, tendons, ligaments, and nerves while reducing inflammation. It shows strong potential for improving gut health (including ulcers and inflammatory bowel disease), promoting angiogenesis (new blood vessel formation), and offering neuroprotective benefits.

Key Benefits of BPC-157

Accelerated Musculoskeletal Healing: BPC-157 is widely used for repairing tendon-to-bone injuries, ligament tears, muscle strains, and fractures.
Gastrointestinal Health: Often termed an “anti-ulcer” agent, it helps protect the gut lining, assists with leaky gut, and reduces inflammatory bowel disease symptoms.
Systemic Anti-inflammatory & Pain Reduction: It acts as a potent anti-inflammatory agent, decreasing swelling and improving mobility.
Angiogenesis (Blood Vessel Growth): The peptide enhances the formation of new blood vessels, which facilitates faster tissue regeneration.
Organ Protection & Repair: Research indicates protective effects on the liver, kidneys, and lungs against damage from stress or toxins.
Neuroprotective Capabilities: Some studies suggest it may help with nerve damage and traumatic brain injuries.

CLICK HERE TO FIND INJECTABLE AND ORAL BPC-157

NAD+: important molecule, but not a peptide

This is my second favorite injection and has transformed my health as well as my skin.

NAD+ should really be discussed separately because it is not a peptide. It is a coenzyme central to redox balance, mitochondrial function, and cellular energy metabolism. That is why it gets bundled into longevity and “cellular optimization” conversations.

NAD+ injections (nicotinamide adenine dinucleotide) offer rapid, direct-to-cell replenishment of a coenzyme that declines with age, boosting cellular energy (ATP), DNA repair, and mitochondrial function. Key benefits include improved cognitive clarity, increased metabolism, accelerated muscle recovery, reduced chronic pain/inflammation, and support for addiction recovery.

Key Benefits of NAD+ Injections:

Anti-Aging and Cellular Repair: NAD+ is critical for activating sirtuins, which repair DNA and regulate aging. It supports cellular regeneration, which can improve skin appearance and increase overall longevity.
Increased Energy and Metabolism: NAD+ helps convert nutrients into fuel (ATP), reducing chronic fatigue and supporting weight loss and healthier metabolism.
Cognitive Function (“Brain Fog”): Enhanced NAD+ levels can improve mental clarity, focus, memory, and concentration. It can aid in neuroprotection by reducing brain inflammation and oxidative stress.
Addiction Recovery and Mental Health: Often used in detox programs, NAD+ injections may help minimize withdrawal symptoms, reduce cravings for substances (alcohol, opioids), and improve mood by supporting neurotransmitter production.
Athletic Performance and Recovery: The injections can improve muscle development and accelerate recovery after intense physical exertion.
Reduced Inflammation and Pain: By supporting cellular health, NAD+ therapy can reduce inflammation throughout the body, helping with chronic pain conditions.

Why Choose Injections over IV?
NAD+ intramuscular injections are a faster, often more affordable alternative to IV therapy, typically taking less than 15 minutes while still bypassing the digestive system for maximum absorption. I have done 7 sessions of NAD IV sessions and they take 8 hours and are extremely uncomfortable. On the other hand, NAD injections are ideal for maintaining consistent, optimal levels of the coenzyme to combat the decline associated with aging.

Click HERE to find injectable NAD

Click HERE to find oral NAD precursors

What peptides can actually do for fat loss, muscle, and optimization

Peptides are not a replacement for training or diet but act as tools that maximize the body’s natural signaling mechanisms. They are most effective when paired with structured exercise and nutrition.

Peptides are not fake. But the peptide world is full of category confusion. These compounds are not cheap, so if you are going to invest in peptides, I would make sure you are optimized in everything else: your hormones are optimized (consider HRT), you prioritize sleep, your diet is on point and you prioritize daily movement. You can use all the peptides in the world, but if you do not have the proper base, you will most likely not notice any benefit.

IMPORTANT TIP ON USING PEPTIDES

All peptides have different protocols on how much to take, when to take, when to take breaks so the body doesn’t get acclimated to the stimulus which can be very confusing. This is an area of expertise that I have been educated in the past 3 years. If you need guidance on what to take when and how much is safe, I would be honored to help you!

CLICK HERE TO FIND THE PEPTIDES THAT I LOVE!

TESTIMONY OF THE DAY

“Prioritizing Protein is the way to go! The before pic was taken 12months ago when I was 20kg heavier & stuck in a stall.

Before discovering Maria I had not only put on weight but had stalled for 12months after following the wrong advice of eating high fat. Changing my macros & adding 2 x PSMF days enabled me to break the stall & lose the last 20kg within 6 months.

However, reaching maintenance is just one amazing benefit of how powerful prioritising protein is. 2yrs ago I started running 5k at a local weekly Parkrun. During my stall I had no energy & was going backward in my running times. Prioritising Protein has increased my energy levels exponentially & I’ve hit a new PB 3 times in 3 weeks! I’m now 102 seconds faster & this morning I reached my running goal of sub 26mins. My recovery after my runs has also been amazing and I can now run another 2k afterwards to catch up to my 92yr old mother who walks the 5k.

I’m now also 3 months post menopausal & can’t believe that I was not only able to lose the excess weight but also all my belly fat, and reach new running goals just by changing my macros to prioritize protein.

If you haven’t discovered Maria’s free Macro calculator or information on PSMF (protein sparing modified fast) then I encourage you to give it a go because it can change different areas of life!” – Nerida