In 1991, Demi Moore made cultural history and sparked a slew of controversy by appearing very pregnant and very naked on the cover of Vanity Fair. Twenty-one years later, Jessica Simpson emulated the pose on the cover of the April 2012 Elle.Though there seem to be more skeptical views of Jessica’s motives, Demi was widely assumed to be posing in an effort to promote acceptance of pregnant bodies as beautiful bodies. Still, after two decades, women continue to struggle with self-acceptance and body image during pregnancy and afterwards.And pregnancy isn’t the only time when your body changes and may get more of your attention. These are some common times of physical transformations and transitions:MORE: Your Pregnant BodyPubertyBig changes happen here, and lots of new information about your body pops up, too. Going through puberty changes your body dramatically, and may also change your self-concept—you’re evolving from a child, to a teenager, and eventually to an adult.It’s possible that your physical changes and emotional changes may not be entirely synchronized, and you may have some discomfort with your new body. You may also need to deal with different reactions from other people, and the new feelings that these reactions may elicit in you. In any event, you’ll need to adjust to your new outer self, and the changes in your inner sense of self that may result.Unfortunately, you’re also going to need to learn how to make sense of the onslaught of unrealistic and often unhealthy “ideal” images thrown at you by our culture. If you’d like to read a story about a group of teenage girls who are challenging the fashion industry this week to use realistic young models and promote positive body image, click here.MORE: Justin Bieber’s Mom FanbaseCollegeCollege is the setting for the famous “freshman 15”—those legendarily unavoidable 15 pounds that creep up on freshman in the land of abundant unhealthy food choices and partying.So, you may start college fairly comfortable in your own skin, and leave your first year with an unwelcomed weight gain. Now is the time to learn or remember general healthy-eating and exercise guidelines. Now is also the time to begin learning to accept and respect your body, regardless of occasional fluctuations in shape and size. This brings us to the next issue…MORE: Your Skin During CollegeThough they’re starting earlier and earlier, eating disorders are rampant on college campuses. Dangerously distorted body images combine with other factors to create disordered eating habits and the associated harsh, critical and potentially deadly self-image. If you think that your thoughts about your body and weight, or your food-related behaviors, are getting out of control, you need to talk to a therapist or doctor and get yourself help in dealing with these issues. For more information, see the “Weighty Issues” chapter in “You: The Owner’s Manual for Teens,” by Dr. Roizen and Dr. Oz.Pregnancy & AfterwardsAs Demi, Jessica and zillions of non-celebrities have discovered, your body will totally change during pregnancy. Growing a child inside of you requires your body to prioritize sustaining that emerging life, over sustaining your size 8 butt and your toned tummy. Though it’s easy to intellectually understand the changes, it may be more difficult emotionally to look in the mirror and embrace the new you.Here, again, is a time for an increased self-nurturing and active efforts to adjust your body image by focusing on the amazing thing you’re accomplishing.After childbirth, it may be difficult to accept that the baby is out, and you’re not instantly bouncing back to your pre-pregnancy shape.  Check out for real-life post-pregnancy images, and women discussing self-acceptance and the re-definition of their concept of beauty.MORE: Best-Dressed Pregnant CelebritiesGetting OlderYup, your body is going to keep changing as you go through your life. You can spend millions of dollars and many hours on treatments, products and procedures to slow the process, but it’s largely inevitable. This doesn’t have to be a bad thing. Life experience gives the potential for greater self-assurance and self-acceptance, as well as an opportunity to find truly satisfying relationships, professional outlets and other endeavors. This internal sense of confidence and contentment will be reflected in your face, in the way you carry yourself and in your general self-presentation.You may find that an improved self-image and a life of fulfillment, along with less stress and general wellness, are some of the best tricks for beautiful aging. Fostering a positive body image throughout your life can lead you through the times of natural transition with a true appreciation of your own inner and outer beauty.MORE: Mid-Life Weight Gain