Keto, fasting, low-fat, paleo — every diet that has ever worked did so through one mechanism: a calorie deficit, taking in fewer calories than you burn. The diets differ only in how they make that deficit easier to sustain. Understanding this frees you from chasing gimmicks.
How a deficit becomes fat loss
One pound of body fat stores roughly 3,500 calories. A daily deficit of 500 calories therefore predicts about one pound of loss per week. It is not perfectly linear in practice — water weight, muscle, and metabolic adjustments all interfere — but the principle holds over time.
Finding your numbers
Start with your TDEE (total daily energy expenditure), the calories you burn in a day. Eat 15–25% below that for steady loss. For someone burning 2,400 calories, that is roughly 1,800–2,000 per day — a cut you can actually live with.
Why crash diets backfire
Very aggressive deficits cost you muscle, tank your energy, and are almost impossible to maintain, leading to rebound eating. A moderate deficit paired with enough protein and strength training protects muscle and keeps the loss off.
Frequently asked questions
Do calories from different foods count the same?
For weight, largely yes, but food quality affects hunger, energy, and health, which makes the deficit far easier to sustain.
Why did my weight loss stall?
As you lose weight you burn fewer calories, so the old deficit shrinks. Recalculate your TDEE periodically.
Try it yourself
Skip the manual math — use a free tool and get the answer instantly:
Results are general information only and not professional financial, medical, or legal advice.