I would be suspicious of any such simplistic formula. For one thing, people's bodily make-up varies according to the proportions of different kinds of tissue. For example, though the energy consumption of fat tissue does contribute significantly to one's basal metabolism, it contributes far less than muscle or brain tissue, so a fatty in bed is likely to waste less of his precious resources on heating the room than an athlete of the same weight. Also, people differ in their genetically determined biochemistry in ways that can drastically affect their energy consumption, whether resting or active. Then again, even the same person's resting energy consumption can change drastically depending on ambient temperature, and his history of fasting, working, stress, fever, the constitution of his food, and the like.

Sorry, got to roll over for gavage now.

Go well,

Jon

You are looking for Basal Metabolic Rate (and possibly Rest Metabolic Rate).

There is much to be said but there's even a strict formula - go on wikipedia and you'll find all the information you need.

http://en.wikipedia.org/wiki/Basal_metabolic_rate

I paste below an excerpt from Wikipedia:

Physiology

Both basal metabolic rate and resting metabolic rate are usually expressed in terms of daily rates of energy expenditure. The early work of the scientists J. Arthur Harris and Francis G. Benedict showed that approximate values could be derived using body surface area (computed from height and weight), age, and sex, along with the oxygen and carbon dioxide measures taken from calorimetry. Studies also showed that by eliminating the sex differences that occur with the accumulation of adipose tissue by expressing metabolic rate per unit of "fat-free" or lean body weight, the values between sexes for basal metabolism are essentially the same[citation needed]. Exercise physiology textbooks have tables to show the conversion of height and body surface area as they relate to weight and basal metabolic values.

The primary organ responsible for regulating metabolism is the hypothalamus. The hypothalamus is located on the brain stem and forms the floor and part of the lateral walls of the third ventricle of the cerebrum. The chief functions of the hypothalamus are:

1. control and integration of activities of the autonomic nervous system (ANS)
   • The ANS regulates contraction of smooth muscle and cardiac muscle, along with secretions of many endocrine organs such as the thyroid gland (associated with many metabolic disorders).
   • Through the ANS, the hypothalamus is the main regulator of visceral activities, such as heart rate, movement of food through the gastrointestinal tract, and contraction of the urinary bladder.
2. production and regulation of feelings of rage and aggression
3. regulation of body temperature
4. regulation of food intake, through two centers:
   • The feeding center or hunger center is responsible for the sensations that cause us to seek food. When sufficient food or substrates have been received and leptin is high, then the satiety center is stimulated and sends impulses that inhibit the feeding center. When insufficient food is present in the stomach and ghrelin levels are high, receptors in the hypothalamus initiate the sense of hunger.
   • The thirst center operates similarly when certain cells in the hypothalamus are stimulated by the rising osmotic pressure of the extracellular fluid. If thirst is satisfied, osmotic pressure decreases.

All of these functions taken together form a survival mechanism that causes us to sustain the body processes that BMR and RMR measure.

Several prediction equations exist. Historically most notable was Harris-Benedict equation, which was created in 1919.

The original equations from Harris and Benedict are:

• for men, 
• for women, 

where P is total heat production at complete rest, m is the weight, h is the stature (height), and a is the age, and with the difference in BMR for men and women being mainly due to differences in body weight.[2] For example, a 55 year old woman weighing 130 lb (59 kg) and 5 feet 6 inches (168 cm) tall would have a BMR of 1272 kcal per day or 53 kcal/h (61.3 watts).

It was the best prediction equation until recently, when MD Mifflin and ST St Jeor in 1990 created new equation:

•  where s is +5 for males and −161 for female. According to this formula, the woman in the example above has a BMR of 1208 kcal per day.

During the last 100 years, lifestyles have changed and a survey in 2005 showed it to be about 5% more accurate.

These formulae are based on body weight, which does not take into account the difference in metabolic activity between lean body mass and body fat. A more accurate formula is the Katch-McArdle formula based on lean body mass:

•  where LBM is the lean body mass in kg.[3] According to this formula, if the woman in the example has a body fat percentage of 30%, her BMR would be 1263 kcal per day.

To calculate daily calorie needs, this BMR value is multiplied by a factor with a value between 1.2 and 1.9, depending on the person's activity level.

I've seen some long winded answers in my time, but these take the biscuit, if you go on to the American College of Sorts Medicine (ACSM) website, you will see a formula of about:

24Kcal/Kg/Day or 1Kcal/Kg/Hour

For some one weighing 10 stone, 63 Kg  this means 1575.

This formula is also used by all fitness professionals in the U.K. and recognised by the U.K. government.