How does this weight loss calculator work?+
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies by an activity factor to find your Total Daily Energy Expenditure (TDEE). It then subtracts calorie deficits of 250, 500, 750, and 1,000 calories per day to show you how quickly you can reach your goal weight at each rate. One pound of body fat equals roughly 3,500 calories, so a 500-calorie daily deficit leads to about 1 pound lost per week.
What is a safe rate of weight loss?+
Most health professionals recommend losing 1 to 2 pounds per week for sustainable, healthy weight loss. Losing more than 2 pounds per week over a long period can lead to muscle loss, nutritional deficiencies, gallstones, and metabolic slowdown. The calculator warns you if a deficit would put your daily intake below 1,200 calories (women) or 1,500 calories (men), which is generally considered the minimum safe intake without medical supervision.
What is the Mifflin-St Jeor equation?+
The Mifflin-St Jeor equation is the most widely recommended formula for estimating Basal Metabolic Rate (BMR). For men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 5. For women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161. Studies show it predicts actual resting metabolic rate within 10% for most people, making it more accurate than the older Harris-Benedict equation.
Why does my weight loss slow down over time?+
As you lose weight your body requires fewer calories to maintain itself, which means your TDEE decreases. This is called metabolic adaptation. A calorie deficit that initially caused 2 lb/week of loss may only produce 1 lb/week after significant weight loss. To continue losing at the same rate you would need to either reduce calories further or increase physical activity. This calculator uses your current weight for the estimate, so recalculate periodically as you progress.
How should I split my macros for weight loss?+
For weight loss, higher protein intake helps preserve muscle mass and keeps you feeling full. A common recommendation is 30% of calories from protein, 35% from carbohydrates, and 35% from fat. This calculator provides macro targets in grams for each deficit level. Protein and carbs each provide 4 calories per gram, while fat provides 9 calories per gram. Adjust the ratio based on your preferences and how your body responds.
Is it safe to eat below 1,200 or 1,500 calories?+
Going below 1,200 calories per day (women) or 1,500 calories per day (men) for extended periods is generally not recommended without medical supervision. Very low calorie diets can cause nutrient deficiencies, muscle loss, fatigue, hair loss, and metabolic adaptation that makes future weight loss harder. If the calculator shows your target falls below these thresholds, consider a more moderate deficit combined with increased physical activity.