Weight Loss Calculator

Max Wishnofsky published the rule in the 1958 Postgraduate Medical Journal article 'Caloric equivalents of gained or lost weight'. He estimated that a pound of human adipose tissue stores about 3,500 kcal, based on adipose tissue being roughly 87 percent fat at 9 kcal per gram plus connective tissue and water. The rule is fine for short-term planning, but Kevin Hall and colleagues (Lancet 2011) showed it systematically overestimates long-term loss because Total Daily Energy Expenditure (TDEE) drops as you lose weight (adaptive thermogenesis). Treat the deficit this calculator returns as a starting estimate, then re-weigh every 2 to 4 weeks. If the trend stalls for 2 to 3 weeks, recompute with your new weight or cut another 100 to 150 kcal rather than slashing intake harder.

A gradual target such as 0.5 to 2 lb per week is common, but a slower rate can still be meaningful and may be more appropriate for a smaller person or someone near a goal weight. Faster loss can include more water and lean tissue and may require clinical supervision. The calculator's band is a planning convention, not a diagnosis that progress below 0.5 lb per week is too small.

The calculator applies fixed planning floors of 1,200 kcal for women and 1,500 kcal for men because lower generic targets are harder to make nutritionally adequate. Those values are not individualized safety guarantees. A very-low-calorie diet is generally defined as less than 800 kcal per day, not any intake below these calculator floors, and it requires medical supervision. Ask a clinician or registered dietitian for a target if the clamp activates or if you have a medical condition, are pregnant, are under 18, or have an eating-disorder history.

The 1,000 kcal warning marks a large generic deficit that may be difficult to sustain and can increase the risk of inadequate nutrition and lean-mass loss. It is not a biological threshold at which metabolism or hormones change abruptly. The appropriate deficit depends on starting weight, health, activity, and clinical supervision.

Scale weight can stall because of water changes, measurement noise, changing adherence, or lower energy needs after weight loss. A two-week flat trend does not prove a specific hormonal cause. Recheck portions and activity, compare weekly average weights, and update the estimate with your current weight. Diet breaks may help some people adhere, but they do not reliably reset metabolism or guarantee further loss. Seek individualized help before making a large additional cut.