Calorie Deficit Calculator

How It Works

One kilogram of body fat contains approximately 7,700 calories of stored energy. To lose one kilogram per week, you need a daily deficit of about 1,100 calories — which is aggressive for most people. A more sustainable rate is 0.5 to 1% of body weight per week. This means a 500-750 calorie daily deficit for most adults. Going too fast leads to muscle loss, metabolic adaptation, nutrient deficiencies, and burnout. The calculator flags when your target intake drops below safe minimums (1,500 cal for men, 1,200 cal for women). If your timeline produces an unsafe deficit, the solution is to either extend the timeline or set a less aggressive target. Remember that weight loss is not linear — water retention, hormonal fluctuations, and digestive contents cause day-to-day weight swings of 1-2 kg.