🔬 Metabolism, explained from first principles

Master your metabolism — from energy balance to fat loss

A seven-part framework — energy balance, BMR & TDEE, macros, fat loss, metabolic adaptation, training, and tracking. Plus free calculators: TDEE, macros, body fat, one-rep max. Learn the why, not just the what.

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The Seven-Part Framework

Follow it in order to build a complete mental model of how your body uses energy.

⚖️ 01

Energy Balance

Calories in vs. calories out — the first law of thermodynamics applied to the body, and why energy balance, not any single food, decides whether you gain or lose.

  • Calories In vs. Out
  • The Energy Balance Equation
  • “A Calorie Is a Calorie”
  • Common Myths
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🔥 02

BMR & TDEE

The four parts of daily burn — BMR, TEF, NEAT, and exercise — how to estimate your TDEE, and why “maintenance calories” are a moving target you confirm with the scale.

  • BMR / RMR
  • TEF · NEAT · EAT
  • Estimating TDEE
  • Finding True Maintenance
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🍳 03

Macronutrients Outline

What each macro does in the body, how much protein actually protects muscle, the truth about carbs and fat, and how to turn a calorie target into a plate.

  • Protein
  • Carbohydrates
  • Dietary Fat
  • Setting Your Macros
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📉 04

Calorie Deficit & Fat Loss Outline

How big a deficit to run, a realistic weekly rate, why the scale lies day to day, and how to hold on to muscle while the fat comes off.

  • Sizing the Deficit
  • Realistic Rate of Loss
  • Scale Weight vs. Fat
  • Keeping Muscle
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🔄 05

Metabolic Adaptation Outline

Adaptive thermogenesis, the “starvation mode” myth versus what really happens, why plateaus appear, and the role of diet breaks, refeeds, and maintenance phases.

  • Adaptive Thermogenesis
  • The “Starvation Mode” Myth
  • Why Plateaus Happen
  • Diet Breaks & Refeeds
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🏋️ 06

Training & Metabolism Outline

Why muscle is metabolically active, resistance training vs. cardio for fat loss, the truth about “afterburn” (EPOC), and how training protects your metabolism in a deficit.

  • Muscle as Metabolic Tissue
  • Resistance vs. Cardio
  • EPOC / “Afterburn”
  • Training in a Deficit
View outline
📐 07

Measuring & Tracking Outline

How to weigh in and read the trend, the limits of BMI and body-fat methods, how to log food without obsessing, and the weekly review that drives every adjustment.

  • Weighing In Right
  • Body-Fat Methods
  • Tracking Food
  • The Weekly Review
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How to use this site

Read in order, run your numbers in the calculators, then apply for 8–12 weeks.

  1. 1

    Energy Balance

    The one rule that governs body weight

  2. 2

    Know Your Numbers

    Calculate your BMR and TDEE

  3. 3

    Build Your Plate

    Set protein, carbs, and fat

  4. 4

    Apply the Deficit

    Lose fat without crashing

  5. 5

    Adapt & Track

    Beat plateaus with data

Free Calculators

Plug in your numbers — everything runs locally in your browser; nothing is uploaded.

The Core Principle

Fat loss comes down to a sustained energy deficit. Macros, training, and meal timing matter only because they help you reach and hold that deficit.

Master the deficit first; optimize the details second.