Calorie Deficit Calculator
A calorie deficit occurs when you consume fewer calories than your body burns. This calculator determines your daily calorie target based on your current weight, goal weight, and preferred rate of weight loss. Sustainable weight loss typically ranges from 0.25 to 1 kg (0.5 to 2 lbs) per week.
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Target daily calories
Key Terms
BMR — Basal Metabolic Rate
The number of calories your body needs to maintain basic functions at rest, such as breathing, circulation, and cell production. This is the minimum energy your body requires to stay alive.
TDEE — Total Daily Energy Expenditure
The total number of calories you burn in a day, including BMR plus all physical activities. Eating below your TDEE creates a calorie deficit for weight loss.
References
- Mifflin, M. D., et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241-247. PubMed
- Frankenfield, D., et al. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. Journal of the American Dietetic Association, 105(5), 775-789. PubMed
- Hall, K. D., et al. (2013). Quantification of the effect of energy imbalance on bodyweight. The Lancet, 378(9793), 826-837. PubMed
- Thomas, D. M., et al. (2010). A computational model to determine energy intake during weight loss. The American Journal of Clinical Nutrition, 92(6), 1326-1331. PubMed
Frequently Asked Questions
A deficit of 500-750 calories daily (producing 0.5-0.75kg weekly loss) is generally safe and sustainable. The American College of Sports Medicine recommends not exceeding 1% of bodyweight loss per week to minimize muscle loss and metabolic adaptation. Deficits below 1200 kcal for women or 1500 kcal for men increase risk of nutrient deficiencies and should only occur under medical supervision.
Metabolic adaptation is the body's reduction in energy expenditure during prolonged dieting, typically 5-15% beyond what weight loss alone would predict (Rosenbaum et al., 2010). Minimize it by: maintaining resistance training to preserve muscle mass, using moderate deficits (15-25% below TDEE), including periodic diet breaks or refeeds, and ensuring adequate protein intake (1.6-2.2g/kg).
Research suggests continuous deficits of 12-16 weeks are generally safe before implementing a diet break. Trexler et al. (2014) found extended dieting beyond 20 weeks significantly increases metabolic adaptation and psychological fatigue. After 12-16 weeks, a 1-2 week period at maintenance calories helps restore leptin levels, reduce cortisol, and improve diet adherence.
Refeed days are planned increases in calories, primarily from carbohydrates, during a fat loss phase. The MATADOR study (Byrne et al., 2018) found intermittent dieting with 2-week maintenance breaks produced 50% greater fat loss than continuous dieting over the same total deficit duration. Single-day refeeds have less metabolic impact but may improve training performance and psychological adherence.
The ISSN and a meta-analysis by Murphy et al. (2021) recommend: protein intake of 1.8-2.2g/kg bodyweight, resistance training 2-4 times weekly with progressive overload, moderate deficits of 500-750 kcal maximum, adequate sleep of 7-9 hours nightly, and limiting cardio to avoid excessive energy expenditure. Rapid weight loss (more than 1% bodyweight weekly) significantly increases muscle loss.
Weight loss deceleration is normal. As you lose weight, your smaller body requires fewer calories (lower TDEE), making your original deficit smaller. Additionally, metabolic adaptation reduces energy expenditure by 5-15% beyond predictions. The NIH Body Weight Planner models show half of expected weight loss occurs in the first year of a diet. Recalculate your TDEE every 5-10kg lost and adjust intake accordingly.