Energy balance determines weight loss and gain, but it's far more complex than simple calorie counting—food label errors reach 20%, metabolizable energy varies by gut microbiome, and non-exercise activity thermogenesis (NEAT) can burn 500–1,000 calories daily. Dr. Layne Norton explains how protein intake, meal timing, artificial sweeteners, seed oils, and creatine actually affect body composition based on human randomized controlled trials rather than hype. Protein intake of 1.6–2 grams per kilogram body weight maximizes muscle retention during fat loss and increases satiety more than carbohydrate or fat, with minimal downsides even at 4 grams per kilogram.