Point is, you have to specify a pound of what. Metabolizing is often measured in terms of calories (potential energy based on raising 1 kg of water 1 degree C, as mentioned by Ed). But different foodstuffs metabolize at different rates, and different activities change the rate of metabolism, and as far as body mass and rate of loss, there are a lot of other factors, such as glandular controls and psychosomatic issues that enter into the equation.
That said, the figure for SWAG purposes is 3500 calories per pound of body weight as a rule of thumb. I don't know what the precision of this doctrine is, but it states if you use up 3,500 calories more than you eat, you'll lose ~ 1 pound.
Here's a blurb from some colukmnist in Utica:
Over time, your additional physical activities have created a caloric deficit. Some common daily activities and their calorie cost:
Chopping wood: 2.3 calories per hour, per pound of body weight.
Trimming hedges: 2.1 calories per hour, per pound of body weight.
House cleaning: 1.6 calories per hour, per pound of body weight.
Mowing the lawn: 2.7 calories per hour, per pound of body weight.
Painting: 2.1 calories per hour, per pound of body weight.
Raking: 1.5 calories per hour, per pound of body weight.
Weeding: 2 calories per hour, per pound of body weight.
Snow shoveling: 3.9 calories per hour, per pound of body weight.
A 130-pound woman who performed one or a combination of these activities for an hour a day would create a 195 to 507 daily calorie deficit.
On average, by performing these activities six days a week you would generate a 22-pound weight loss in a year. Although this is a relatively simple method for reaching one's ideal body weight, our society is preoccupied with instant results without exerting a great deal of energy.