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Weight Loss Calculator

See exactly when you'll reach your goal weight — based on your metabolism, activity, and calorie intake.

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Your Weight Loss Timeline

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Estimated Time to Goal
Estimated goal date: —
Weekly Loss
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Daily Deficit
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Total to Lose
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Weight Milestone Timeline

These projections assume a constant calorie intake and activity level. In practice, your metabolic rate decreases slightly as you lose weight (adaptive thermogenesis), so actual results may be 10–15% slower than projected. Re-calculate every 4–6 weeks for accuracy.

How Weight Loss Works

Weight loss comes down to one principle: energy balance. When you consume fewer calories than your body burns, it taps into stored energy (primarily body fat) to make up the difference. This is called a calorie deficit.

The math: 1 kg of body fat stores approximately 7,700 kcal of energy. To lose 0.5 kg per week, you need a daily deficit of about 550 kcal — achievable by eating less, moving more, or both.

It takes a deficit of roughly 7,700 kcal to lose 1 kg of body fat (or 3,500 kcal per pound). So a daily deficit of 500 kcal produces about 0.45 kg (1 lb) of fat loss per week — and a 1,000 kcal deficit doubles that to ~0.9 kg (2 lbs) per week.

Your body burns calories through three channels: Basal Metabolic Rate (BMR) — the energy needed to keep organs, brain, and cells running at rest (60–75% of total burn); the Thermic Effect of Food (TEF) — energy used digesting meals (~10%); and Physical Activity — everything from walking to intense exercise (15–30%). Together, these make up your Total Daily Energy Expenditure (TDEE).

Safe Weight Loss Pace

Not all deficit sizes are equally sustainable. A smaller deficit is easier to maintain, preserves more muscle mass, and is less likely to trigger metabolic adaptation. Here's a breakdown of common weight loss paces:

PaceWeekly LossDaily DeficitNotes
Gentle0.25 kg (0.55 lbs)~275 kcalVery sustainable, minimal hunger
Moderate0.5 kg (1.1 lbs)~550 kcalRecommended for most people
Fast0.75 kg (1.65 lbs)~825 kcalRequires discipline, some muscle risk
Aggressive1.0 kg (2.2 lbs)~1,100 kcalHard to sustain, higher muscle loss risk

Medical guidelines generally recommend losing no more than 0.5–1 kg per week. Going faster increases the risk of muscle loss, nutrient deficiencies, gallstones, and metabolic slowdown. Never eat below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.

Why Weight Loss Slows Down

Adaptive thermogenesis is your body's survival mechanism. As you lose weight, your body becomes more efficient — burning fewer calories at rest and during activity. Studies show metabolic rate can drop by 10–15% beyond what weight loss alone would predict. This is why the last few kilograms feel so much harder than the first.

Adaptive thermogenesis: A landmark study by Fothergill et al. (2016) — following Biggest Loser contestants — found that participants' metabolisms slowed by an average of 500 kcal/day more than expected 6 years after the show. Gradual weight loss minimizes this effect.

Water weight fluctuations are the biggest source of day-to-day confusion. Starting a diet often causes a dramatic initial drop (2–3 kg in the first week) as your body depletes glycogen stores, each gram of which holds 3–4 grams of water. Conversely, a high-sodium meal or carb-heavy day can add 1–2 kg overnight — none of which is fat.

The plateau effect: As you get lighter, your TDEE decreases because there's less body mass to fuel. A deficit that worked at 90 kg might be maintenance at 75 kg. This is why recalculating your calorie target every 4–6 weeks is essential for continued progress.

Tips for Sustainable Weight Loss

  • Prioritize protein: Aim for 1.6–2.2 g per kg of bodyweight daily. Protein preserves muscle during a deficit, increases satiety, and has a higher thermic effect than carbs or fat.
  • Track consistently: You don't have to track forever, but logging meals for a few weeks builds awareness of portion sizes and calorie-dense foods that cause overshoot.
  • Weigh yourself daily, judge weekly: Daily weight fluctuates due to water, sodium, and digestion. Use the weekly average to assess real progress.
  • Strength train: Resistance training is the single best tool for preserving muscle mass during weight loss. Even 2–3 sessions per week makes a significant difference.
  • Sleep 7–9 hours: Poor sleep increases ghrelin (hunger hormone) by up to 28% and decreases leptin (satiety hormone), making your deficit feel much harder than it needs to be.
  • Take diet breaks: Eating at maintenance for 1–2 weeks every 8–12 weeks of dieting can restore leptin levels, reduce fatigue, and improve long-term adherence.
  • Don't drink your calories: Liquid calories (juice, soda, alcohol) don't trigger satiety signals the way solid food does. Swapping to water, coffee, or tea can save 200–500 kcal/day effortlessly.
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