Lean-mass

Rapid weight loss produces specific physiological consequences beyond simple fat reduction: lean mass loss, metabolic rate suppression, gallstone formation, nutrient deficiencies, and psychological rebound. This article reviews the evidence behind each risk and what rate of loss minimises them.

Protein's role in weight loss operates through three mechanisms: thermic effect (~150 kcal/day at 150g protein), satiety (Weigle 2005: −440 kcal/day at 30% protein), and lean mass preservation (Stiegler 2006: reduces lean mass loss from 25% to 8–12% of weight lost). Target is 1.6–2.0g/kg/day. This article covers the evidence and practical food sources.

Dieting creates metabolic challenges: adaptive thermogenesis and lean mass catabolism both reduce resting metabolic rate during caloric restriction. This article covers the physiological mechanisms, how to quantify the risks, and the specific strategies that counteract metabolic adaptation while sustaining fat loss.

NICE recommends 0.5–1 kg/week as the safe rate of weight loss for most adults (500–600 kcal/day deficit). Faster rates increase lean mass loss and gallstone risk. Slower rates are equally valid. This article covers what determines a healthy rate, what happens at different rates, and how to calibrate your approach.

Testosterone enanthate (Test E) is a long-acting testosterone ester used medically for hypogonadism. It improves body composition by increasing lean mass and reducing fat mass — but these effects occur primarily in hypogonadal men. This article reviews the evidence on testosterone and body composition, the medical context, and risks of non-medical use.