A good rule of thumb is 13 calories per pound of body weight for a sedentary person of either sex, 16 calories per pound for a moderately active person, and 18 calories per pound for a vigorously active person.
The question that we asked in my lab is, what's the least amount of " movement breaks" that we need in order to offset the harms of being highly sedentary?
But on the subject of obesity, she pointed out that consumers' lifestyles have changed significantly, with many people being more sedentary not least because more time is spent in front of computers.
For example, if you're a woman in your 30s or 40s, and you live a rather sedentary lifestyle—meaning you don't set aside time for any exercise—then probably don't need any more than 1800 calories on average.