Calculate how long it will take to reach your target weight with a safe and sustainable calorie deficit.
Last updated: March 2026
Disclaimer: This calculator uses a simplified model based on a 7700 kcal/kg fat assumption. Real weight loss is rarely linear—you may experience plateaus, water-weight fluctuations, and metabolic adaptation. A 1200 kcal daily minimum is enforced for safety, but should only be used under professional supervision. Timeline predictions assume consistent adherence and no changes in metabolism, activity level, or composition.
Actual results vary ±15-30% based on age, metabolic rate, hormonal factors, sleep quality, stress, and exercise adherence. Sustainable weight loss (<0.5-1 kg per week) is safer than rapid approaches. Consult a healthcare professional or registered dietitian before making significant dietary changes, especially for medical conditions or extreme deficits.
Don't know your TDEE? Use our TDEE Calculator
Sustainable weight loss is achieved through a moderate calorie deficit that preserves muscle mass, maintains energy levels, and can be followed long-term. The key is creating a deficit large enough to lose fat consistently but small enough to avoid metabolic adaptation, excessive hunger, and nutritional deficiencies. Research shows that losing 0.5-1% of body weight per week is optimal for most people.
One kilogram of body fat contains approximately 7,700 calories. To lose weight, you must create a calorie deficit—consuming fewer calories than you burn. A 550-calorie daily deficit creates a 3,850-calorie weekly deficit, resulting in approximately 0.5kg fat loss per week. This calculator uses your Total Daily Energy Expenditure (TDEE) to determine safe calorie targets based on your desired loss rate.
The calculator enforces a minimum of 1,200 calories daily for safety. Very low-calorie diets can slow metabolism, cause muscle loss, trigger nutritional deficiencies, and are difficult to sustain. Gradual weight loss (0.25-0.75 kg/week) is more likely to be maintained long-term compared to rapid crash dieting, which typically results in 80-95% regaining the weight within 1-5 years.
The calculator uses the established calorie-per-kilogram relationship:
The calculator enforces a 1,200 calorie minimum (1,500 for men is often recommended). Going below this threshold increases risk of nutrient deficiencies, muscle loss, metabolic slowdown, and difficulty sustaining the diet. If the calculator suggests 1,200 calories and you want a larger deficit, increase activity instead of decreasing calories further.
Scenario: 90kg person wants to reach 75kg (15kg loss), TDEE = 2,400 kcal/day, moderate rate
Moderate (0.5 kg/week) is recommended for most people. Choose slow if you're already lean (sub-15% body fat for men, sub-25% for women) or have less than 10kg to lose. Choose fast only if you have 20+ kg to lose and are medically supervised. Faster isn't always better—sustainability matters more than speed.
Going below 1,200 calories daily (1,500 for men) makes it nearly impossible to get adequate protein, vitamins, and minerals. It also slows metabolism, causes muscle loss, triggers intense hunger, and is unsustainable. If you need a larger deficit, increase activity rather than decreasing calories below this threshold.
Use our TDEE Calculator, which estimates calories burned daily based on age, weight, height, gender, and activity level. Alternatively, track your current calorie intake and weight for 2 weeks—if weight is stable, your intake equals your TDEE. TDEE decreases as you lose weight, so recalculate every 5-10kg.
You can create a larger deficit, but it comes with risks: increased muscle loss, metabolic adaptation (slower metabolism), nutrient deficiencies, fatigue, hormonal disruption, and higher likelihood of regaining weight. Research shows aggressive diets have 90%+ failure rates long-term. Slow and steady wins.
Weight loss plateaus are normal. As you lose weight, your TDEE decreases, so recalculate and adjust your calorie target. Also consider: water retention masks fat loss, muscle gain offsets fat loss on the scale, and metabolic adaptation can slow progress. Take diet breaks every 8-12 weeks to restore metabolism.
If you calculated TDEE including your typical exercise, don't eat back exercise calories—they're already accounted for. If you used sedentary TDEE, you can eat back 50-75% of estimated exercise calories (not 100%, as estimates are often inflated). Consistency in approach matters most.
Aim for 1.6-2.2g protein per kg of body weight (or 0.8-1g per pound). High protein preserves muscle mass during calorie deficits, increases satiety (fullness), and has a higher thermic effect (burns more calories digesting). This becomes critical when calories are restricted.
Recalculate every 5-10kg of weight loss or if you plateau for 2+ weeks despite adherence. As weight decreases, so does TDEE, requiring calorie adjustments. Also recalculate if activity level changes significantly (new job, training program, injury recovery).
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