In Dr. Tristi Muir’s latest Our Bodies, Our Lives column: The average weight gain during midlife is 10 to 15 pounds. Is aging a battle that we must lay down our weapons against and accept as an eventuality? Many women have picked up the sword to fight aging by covering up that gray hair or using skin products or Botox to soften wrinkles. But what about the pounds in the middle? There are many changes in our bodies and activities as we age that can lead to weight gain.