I agree that the 'right' number of calories for any given individual is the number of calories they need to maintain a healthful weight and energy level; the answer won't be exactly the same for any two people, given the variation in genes regulating basal metabolism. You may be interested to know we burn calories in three ways: physical activity, heat generation, and basal metabolism, also known as resting energy expenditure. That last one is by far the largest contributor, accounting for as much as 70% of the total, and varies with our genetic endowment. We can change it by building or losing muscle, but it is substantially beyond our control.

That said, there are formulas for calculating the 'average' energy requirement for an individual based on sex, size, and activity level. The simplest of these in your case is 30kcal/kg per day to maintain a weight that is already in the normal range. More elaborate formulas are generally based on something called the Harris-Benedict equation, and updates to it. Rather than torment you with the details, here is a shortcut: you can enter some information on-line, and let a freely available calculator do the work for you. This is available at various places in cyberspace, but here's a good one: http://www.freedieting.com/tools/calorie_calculator.htm.

I made up an entry for you, assuming you were 5'4", weighed 145lbs, and were 42 years old and were, as you stated, sedentary. The result for weight maintenance was 1565 calories per day.

Best,
David L. Katz, MD, MPH, FACPM, FACP
Yale Prevention Research Center