Calorie Deficit Calculator

A calorie deficit occurs when you consume fewer calories than your body burns over a given period. Your body then turns to stored energy · primarily body fat · to make up the shortfall. A deficit of approximately 7,700 kcal is commonly cited as the energy equivalent of 1 kg of body fat, though actual weight loss varies based on water retention, muscle changes, and metabolic adaptation.

A moderate deficit of 500-750 kcal/day is generally recommended for sustainable fat loss, targeting roughly 0.5-0.75 kg (1-1.5 lbs) per week. Very aggressive deficits above 1,000 kcal/day increase the risk of muscle loss, nutrient deficiencies, fatigue, hormonal disruption, and rebound weight gain. For very overweight individuals, larger initial deficits may be appropriate under medical supervision.

Some muscle loss can occur during caloric restriction, but it can be substantially minimized by: maintaining adequate protein intake (1.6-2.2 g per kg of body weight), continuing resistance training during the deficit, and keeping the deficit moderate rather than extreme. Very-low-calorie diets without adequate protein and exercise cause the most muscle loss.

Weight loss plateaus are common and have several causes: metabolic adaptation (the body reduces BMR in response to caloric restriction), water retention masking fat loss, underestimating calorie intake (a common issue with food tracking), or an overestimation of calories burned through exercise. Strategies to overcome a plateau include recalculating your TDEE based on your new lower weight, introducing diet breaks, and varying exercise intensity.