Daily Calorie Calculator

Formulas Used

This calorie calculator is based on several equations, and the results are based on estimated averages. The Harris-Benedict Equation was one of the earliest equations used to calculate basal metabolic rate (BMR), which is the amount of energy expended per day at rest. It was revised in 1984 to be more accurate and was used until 1990, when the Mifflin-St Jeor Equation was introduced.

The Mifflin-St Jeor Equation also calculates BMR and has been shown to be more accurate than the revised Harris-Benedict Equation. The Katch-McArdle Formula is slightly different as it calculates resting daily energy expenditure (RDEE), which takes lean body mass into account, something neither the Mifflin-St Jeor nor the Harris-Benedict Equation do.

Of these equations, the Mifflin-St Jeor Equation is considered the most accurate for calculating BMR, with the exception that the Katch-McArdle Formula can be more accurate for people who are leaner and know their body fat percentage.

The value obtained from these equations is the estimated number of calories a person can consume in a day to maintain their body weight, assuming they remain at rest. This value is multiplied by an activity factor (generally 1.2-1.95) dependent on a person's typical levels of exercise.

1 pound, or approximately 0.45 kg, equates to about 3,500 calories. As such, to lose 1 pound per week, it's recommended to reduce 500 calories from the estimated maintenance calories per day. For example, if a person has an estimated allotment of 2,500 calories per day to maintain body weight, consuming 2,000 calories per day for one week would theoretically result in 3,500 calories (or 1 pound) lost during that period.

It's important to remember that proper diet and exercise are widely accepted as the best approach to weight management. It's not advisable to lower calorie intake by more than 1,000 calories per day, as losing more than 2 pounds per week can be unhealthy and may have the opposite effect in the near future by reducing metabolism.

Losing more than 2 pounds a week will likely involve muscle loss, which in turn lowers BMR, since more muscle mass results in higher BMR. Excessive weight loss can also be due to dehydration, which is unhealthy. Furthermore, particularly when exercising in conjunction with dieting, maintaining a good diet is important, as the body needs to support its metabolic processes and replenish itself.

Depriving the body of the nutrients it requires through unhealthy diets can have serious detrimental effects, and weight lost in this manner has been shown in some studies to be unsustainable, as the weight is often regained in the form of fat (putting the person in a worse state than when beginning the diet). As such, in addition to monitoring calorie intake, it's important to maintain adequate fiber intake and other nutritional necessities to balance the needs of the body.