Quick Answer: The thrilling 2-4kg drop in weeks 1-2 is mostly water: cutting calories (especially carbs) depletes glycogen, which releases the ~3g of water stored with every gram of it. Week 3’s ‘crash’ to 0.25-0.75kg per week isn’t your diet failing — it’s water noise ending and actual fat-loss speed becoming visible. The people who quit at week 3 quit at the exact moment real progress became measurable.

Every diet has the same emotional arc: euphoria at the week-one whoosh, quiet pride at week two, and existential doubt at week three when the scale slows to a crawl on the identical routine. The routine didn’t change — the physics just finished its opening act.

Where does the early whoosh actually come from?

Three water reservoirs drain in weeks 1-2:

• Glycogen water (the big one): your muscles and liver store carbohydrate as glycogen — several hundred grams of it — and each gram holds roughly 3 grams of water. A calorie deficit (especially with fewer carbs) taps those stores, and the water ships out with them: 1.5-3kg of scale weight that was never fat.
• Sodium-shift water: diets that swap processed food for home cooking slash sodium — and lower sodium means less retained fluid, another quick kilogram for many.
• Gut contents: eating less volume simply means less in-transit mass at any weigh-in moment. Unglamorous, real, and also not fat.

Actual fat loss in those same weeks? Present and normal — at roughly the rate a sensible deficit produces: ~0.25-0.75kg weekly. It was just hiding inside a much larger water story, like a steady drumbeat under a fireworks show.

Why is understanding this diet-saving?

Because the misread at week 3 is the classic quit trigger:

The wrong story: ‘I lost 2kg a week at first, now 0.4kg — my metabolism crashed / the diet stopped working / I need something stricter.’ This story leads to slashing calories harder (unsustainable), program-hopping (resetting the water cycle each time — which is exactly why serial diet-switchers keep experiencing thrilling first weeks), or quitting.

The right story: ‘The water chapter ended; 0.4kg weekly IS the fat-loss speed, was all along, and it’s exactly on target.’ This story leads to… continuing. Which is the entire game.

The expectation calibration to install on day one: weeks 1-2 are a physics prologue — the diet’s true pace appears at week 3, and that pace is the one to judge. Bonus insurance: measure waist and take photos at day zero, because when the scale enters its boring era, the tape keeps reporting fat-specific progress the water noise can’t touch.

Myth vs Fact: Early Weight Loss Edition

Myth: The week-3 slowdown means your metabolism ‘adapted’ and stalled. Fact: Metabolic adaptation is real but modest and gradual — the week-3 cliff is water accounting ending, not your metabolism collapsing on schedule. (True plateaus — 3-4+ weeks of nothing on honest adherence — have their own checklist, later in the journey.)

Myth: Regaining 1-2kg after one indulgent weekend means the fat came back. Fact: Same physics in reverse — refilled glycogen and sodium bring their water home. Fat regain requires a sustained surplus of thousands of calories; a salty carby weekend restores water weight that will leave again within days of resuming. The Monday scale after a wedding is reporting hydration, not failure.

Myth: A faster whoosh means a better diet. Fact: Aggressive low-carb openings produce the biggest water drops — impressive, and largely refundable on the first normal-eating week. Comparing diets by week-one numbers is comparing them by their water chemistry, not their sustainability or fat-loss math.

The pattern: nearly every early-diet emotional whiplash — the euphoria, the crash, the weekend panic — is water physics being mistaken for verdicts. This is general information, not medical advice.

FAQ: Early Weight Loss Questions, Answered

What’s a realistic ongoing rate after the water chapter?

Common sustainable territory: 0.25-0.75kg (0.5-1% of bodyweight) weekly, slower for lighter people and gentler deficits. Judged as a 3-4 week trend of weekly averages — single weigh-ins stay noisy forever.

Should I weigh daily or weekly?

Either works with the right processing: daily-weights-weekly-average smooths the noise best (and desensitizes the daily number’s drama); a single weekly weigh-in (same morning, same conditions) suits people the daily number stresses. The veto rule from recomp applies here too: the scale gets a vote, not the verdict.

Does the water weight ever ‘come back’ while dieting?

Fluctuations visit constantly — salty meals, cycle phases, hard workouts (muscle repair holds water), travel. Expect 1-2kg oscillations around a declining trend line, and read the line, not the oscillations. A flat month on honest adherence is a real checkpoint worth troubleshooting; a flat Tuesday is Tuesday. This is general information, not medical advice.

TL;DR:

• Weeks 1-2 = glycogen water (~3g water per gram), sodium shifts, and gut contents — the fat-loss drumbeat (0.25-0.75kg/wk) was underneath all along
• Week 3’s ‘crash’ is water noise ending — the moment real progress becomes measurable is the moment most people quit
• Post-weekend jumps are water refilling, refundable within days; fat regain needs sustained surplus
• Install day-zero tape measurements and photos as scale-noise insurance; judge 3-4 week trends only

The fireworks were never the show — the drumbeat was, and it never stopped playing. This is general information, not medical advice.