The skin changes that occur in the face will also occur on the body, but they will be less severe unless there has been significant sun exposure over the years. The reasons are the same as for the face: loss of collagen and elasticity, gravity, and so on.
Regarding the breasts, we have to consider the effects of aging, pregnancy, and breast feeding. The effects of pregnancy and breast feeding can vary, but most women will experience a volume loss in the breast, primarily above the nipple, and the result will be loose, sagging skin. Aging will also cause sagging of the breasts and some women will experience an increase in breast size around menopause, usually related to weight gain.
In many cases, the problem of loose, sagging breasts can be corrected simply by adding volume through a breast augmentation. If the sagging is severe, then a breast lift & augmentation may be necessary. For women who have sagging breasts but are satisfied with their breast size in a bra, then a breast lift, or mastopexy, alone will take care of it.
The arms and legs develop loose and sagging skin with advancing age, but the biggest changes you will see are in the trunk or torso. The number one complaint that I hear from my patients is a loss of their feminine shape. There is usually an expansion of the waistline due to hormonal changes of menopause, which cause an accumulation of fat, in addition to the loss of muscle tone that occurs with aging. Even women who are naturally thin seem to lose their feminine curves. These changes are compounded by pregnancy which stretches the abdominal muscle attachments and expands the ligaments of the pelvis.
Knowing what happens, or is going to happen, is all well and good, but what is there to do about it. Well, you can accept it or you can fight it, but if you are going to fight it, set reasonable expectations because aging is a normal process that can't be stopped and you don't want to end up frustrated.
Eating sensibly and exercise are the first steps to blunt (not stop) the effects of the aging process. For stubborn fat deposits that won't respond to your efforts, liposuction may be an option. If your problems are due to loose skin or stretched out abdominal muscles, a tummy tuck would probably be the right procedure for you.
The most important thing to remember is bodily changes due to aging and pregnancy are a normal part of life, so don't get too frustrated or blame yourself. Whatever you decide to do about it is a personal choice that should be made by you and for you.