Why Do Women Need Fewer Calories? - as part of the expert series by GeoBeats. Women actually do not necessarily need fewer calories than men. What happens is men tend to have more muscle than women, which would equate to a higher calorie need. The amount of calories that you need in order to maintain a healthy body weight is based on three different things. The first thing is your resting metobolic rate, which means how many calories you specifically need at rest, if you were not doing anything at all, not moving and not doing excersize. And this is because your organs still need calories to function, breathing takes calories to function and a large part of this is maintenance of lean body mass which is muscle mass. So the more muscle you have, the more calories you need. The other part of the equation is movement. The more you move the more calories that you need. And of course, last but not least, exercise. So people who exercise are able to maintain a healthier body weight and eat a little bit more than those who do not. So gain, it does not necessarily mean that men need more calories than women, it is just that men tend to have more muscle mass and women tend to have more fat mass. If you take a very active woman who has much less fat mass and much more lean body mass, as opposed to a sedentary man who has much more body fat, she might need more calories than he does. So it really does not matter if you are male or female the amount of calories you need really depends on how much you move, genetics, and again, how much muscle mass you have. Weight and height also play a difference.