Calorie Deficit: The Only Weight Loss Rule That Actually Matters
Every diet works through the same mechanism. Here is the science of energy balance explained simply.
Every successful diet — keto, paleo, intermittent fasting, Weight Watchers, vegan — works through one mechanism: a calorie deficit. You eat fewer calories than you burn. The method you use to achieve the deficit is a personal preference; the deficit itself is the universal requirement.
Finding Your Deficit
Step 1: Calculate your TDEE (total daily energy expenditure). Step 2: Subtract 500 calories for 1 pound per week loss, or 1,000 for 2 pounds. Step 3: Do not go below 1,200 (women) or 1,500 (men) without medical supervision. A 500-calorie deficit is sustainable and preserves muscle. A 1,000-calorie deficit is aggressive and risks muscle loss and metabolic adaptation.
Why Diets Fail
The deficit is too large (unsustainable). No tracking (you eat more than you think). Weekend overconsumption (5 days of deficit erased by 2 days of surplus). Liquid calories (smoothies, alcohol, coffee drinks). The most reliable approach: moderate deficit (500 cal), high protein (prevents muscle loss), and strength training (preserves metabolism).