REBUILD
Lean tissue does not leave slowly. Under the conditions created by rapid weight loss, the body sacrifices muscle with the same efficiency it loses fat. The difference is that fat loss is the goal. Muscle loss is the cost.
What changes
Muscle is metabolically expensive tissue. The body maintains it willingly when the anabolic signals are present — sufficient protein, adequate hormonal environment, mechanical demand, and the nutritional substrates required for protein synthesis. Rapid, pharmaceutical-assisted weight loss disrupts all four simultaneously.
Caloric restriction reduces protein synthesis rates. Reduced food volume and GLP-1's suppression of appetite lower dietary protein intake. The resulting catabolic state — where the body draws energy from lean tissue rather than fat stores alone — is not a malfunction. It is the body operating exactly as designed under energy deficit conditions.
The STEP-1 trial, published in the New England Journal of Medicine, documented that between 39% and 45% of total weight lost during semaglutide treatment came from lean tissue. That finding has been replicated across multiple subsequent trials. It is not a side effect of poor protocol execution. It is a documented biological consequence of the mechanism that makes GLP-1 therapy effective.
What the research has not yet sufficiently addressed is the hormonal environment underlying that lean tissue loss — and what can be done to support it.
During significant caloric restriction, cortisol — the body's primary stress and catabolic hormone — rises. Testosterone — the primary anabolic hormone governing lean tissue synthesis and preservation — falls. The resulting shift in the cortisol-to-testosterone ratio is one of the most powerful determinants of whether lean tissue is preserved or sacrificed during weight loss. Without targeted intervention to support that hormonal environment, the catabolic state persists well beyond the period of active weight loss.
REBUILD — KSM-66® ASHWAGANDHA (WITHANIA SOMNIFERA) — CORTISOL MODULATION AND ANABOLIC SUPPORT
The relationship between cortisol and lean tissue loss is direct and well-established. Chronically elevated cortisol — the predictable result of sustained caloric restriction and metabolic stress — suppresses testosterone production, accelerates protein catabolism, and inhibits the signalling pathways required for muscle protein synthesis.
KSM-66® is the world's most clinically studied Ashwagandha extract — a full-spectrum root extract standardised to preserve the complete profile of active withanolides. Its clinical evidence base is among the most robust of any adaptogenic compound available.
A 2022 systematic review published in Medicina analysed randomised placebo-controlled trials and found that Ashwagandha supplementation was associated with significant improvements in testosterone levels, muscle strength, and cortisol reduction compared to placebo. A 12-month prospective safety study published in 2025 confirmed that serum cortisol declined and testosterone increased significantly across the treatment period — with no adverse effects on hepatic, renal, or thyroid function.
REBUILD — TONGKAT ALI ROOT EXTRACT 100:1 (EURYCOMA LONGIFOLIA) — TESTOSTERONE SUPPORT
Tongkat Ali has one of the most thoroughly documented testosterone-supporting profiles in herbal medicine. A 2022 systematic review and meta-analysis published in Medicina, analysing randomised clinical trials according to PRISMA guidelines, found significant improvements in total testosterone levels following Eurycoma longifolia supplementation in both healthy volunteers and men with low testosterone.
A randomised, double-blind, placebo-controlled multicentre trial published in Food and Nutrition Research (2021) — enrolling 105 male subjects over 12 weeks — found that Eurycoma longifolia supplementation produced significant increases in both total and free testosterone levels. A 6-month randomised, double-blind, placebo-controlled trial published in Maturitas further confirmed that Eurycoma longifolia combined with physical activity significantly increased total testosterone levels in men with androgen deficiency.
The mechanism is distinct from direct hormone replacement. Eurycoma longifolia works by reducing the binding of testosterone to sex hormone-binding globulin — freeing existing testosterone for biological use. This makes it particularly relevant in the context of caloric restriction, where SHBG levels typically rise and biologically available testosterone falls even when total testosterone appears stable.
REBUILD — ZINC BISGLYCINATE CHELATE — FOUNDATIONAL HORMONAL MINERAL
Zinc is the mineral most directly involved in testosterone synthesis, protein metabolism, and immune function — three systems under simultaneous pressure during rapid weight loss. Zinc deficiency — which develops rapidly under conditions of reduced dietary intake — is documented to suppress testosterone production and impair protein synthesis independently of caloric status.
Zinc Bisglycinate Chelate is the most bioavailable form of supplemental zinc available. Unlike zinc oxide or zinc sulphate — the cheaper forms found in most supplements — the bisglycinate chelate form binds zinc to glycine molecules, dramatically improving absorption and tissue delivery. This is precisely the formulation distinction that matters when the gut environment is compromised and absorption efficiency is reduced.
REBUILD — BEET ROOT EXTRACT AND POMEGRANATE EXTRACT (STD. 40% ELLAGIC ACID) — CIRCULATION AND VASCULAR SUPPORT
Nutrient delivery to muscle tissue is dependent on blood flow. Both Beet Root Extract — a clinically studied source of dietary nitrates that support nitric oxide production and vascular function — and Pomegranate Extract standardised to 40% Ellagic Acid — a potent polyphenol with documented antioxidant and circulatory support properties — address the vascular environment required for efficient nutrient and oxygen delivery to skeletal muscle.
The outcome
Lean tissue preservation is not achieved by supplementation alone. It requires resistance training, adequate protein intake, and the right hormonal and nutritional environment to signal that existing muscle is worth protecting. REBUILD addresses the hormonal and nutritional side of that equation — specifically targeting the cortisol-to-testosterone ratio, the mineral deficiencies that develop under caloric restriction, and the vascular conditions that determine whether nutrients reach the muscle tissue that needs them.
The muscle that is preserved during the GLP-1 lifecycle is the muscle that sustains metabolism, maintains strength, and determines whether the results of successful weight loss compound or erode over time.