Caroline, a 53-year-old housewife from Chicago, Ill., weighs exactly what she did 30 years ago on her wedding day, but her wedding dress no longer fits. Much to her dismay, Caroline's waist is expanding, even though she hasn't put on any weight. She works hard at "keeping her figure" by exercising, eating mostly fish and vegetables and rarely consuming sugar. So why don't her belts close on the same hook as they did last year?

Then there's Susan, a 60-year-old retired schoolteacher from New Haven, Conn., who has gained 15 pounds in the last few years, despite her devotion to a healthy, active lifestyle. And Ellie, a 59-year-old woman from San Francisco, Calif., who isn't surprised by the changes in her body, because she's never exercised and admits to indulging frequently in foods she knows she should avoid.

Three different women; three similar journeys through menopause. Is the menopausal weight issue an inevitable annoyance, or can it be avoided?

Protective or risky?

The transition through menopause is typically burdened with significant weight gain - about 1.5 pounds per year during the middle years, regardless of initial age, initial body size, or ethnicity, according to data from the Study of Women's Health Across the Nation (SWAN,) a multi-ethnic, community-based, longitudinal study of more than 3,000 women (American Journal of Epidemiology, November 2004.) However, there is broad debate among scientists over why and how this weight gain occurs.

Debra Waterhouse, M.P.H, R.D., author of "Outsmarting the Female Fat Cell," says, "From my experience, most women need to gain two to five pounds during this time. Fat cells are your menopause helper." She believes the weight (or fat) gain is protective and necessary to help a woman get through menopause, because as menopause approaches and ovarian estrogen levels decline, a woman's fat cells can take over producing estrogen to help her get through this menopausal transition.

But Margery Gass, M.D., practicing gynecologist and executive director of the North American Menopause Society, disagrees. "The kind of estrogen produced by fat cells after menopause is not as potent as what is produced by the ovaries before menopause."

So, there's no real certainty the postmenopausal estrogen actually does ease the transition. Gaining a couple of pounds as you age might not affect your overall health, but experts stress excess weight can increase the risk for stroke, cardiovascular disease, cardiovascular mortality and all-cause mortality among the middle-aged.

Changing body shape. Even women who don't gain any weight may experience a loss of muscle mass and a shift in body fat distribution to the abdomen, signaling the need to switch from belts to elastic waistbands.

Carrying excess weight in the abdomen is referred to as "central obesity," which is associated with a condition called metabolic syndrome (MetS), a cluster of risk factors known to increase the risk for developing cardiovascular disease (CVD), diabetes and some forms of cancer. Yet, scientists don't fully understand why body shape changes as we age. Gass conjectures the shift of fat to the abdomen might be due to loss of skin elasticity and muscle tone, characteristic signs of aging.

Enter hormones

Women have both estrogen and testosterone floating around in their bloodstream at all times. But as women age, these hormones fluctuate, creating scenarios in which one becomes more predominant than the other.

During menopause, there are periods when testosterone dominates over estrogen, producing a more "male-like" hormonal situation. Since men tend to put on weight in their abdominal region, the redistribution of fat during menopause may not be due so much to estrogen decline as to the influence of testosterone. This fluctuating hormone environment can also impact appetite.

Estrogen appears to act as an appetite suppressant. Research shows that the fluctuation of estrogen as women approach their menstrual cycle can result in increased appetite. It is thought that during periods when estrogen levels are lower, food intake might increase enough to account for some weight gain women experience.

Jennifer Lovejoy, Ph.D., adjunct faculty at Bastyr University (Seattle, Wash.) and University of Washington School of Public Health, and president of The Obesity Society, studies the effects of these hormones on obesity. She has observed slight increases in food intake related to estrogen decline during the perimenopausal transition that might account for a 2- to 5-pound increase in weight, but not for the shift in fat that seems to happen even in women who don't gain weight.

Maybe weight gain is not inevitable. As women age, if they exercise less and lose body muscle mass, their calorie needs decline. So, do the math: If your calorie needs decline and you continue to eat the same (or an even higher) number of calories, weight gain will naturally result.

Results from the Massachusetts Women's Health Study published in 2000 in Menopause led researchers to conclude menopause transition is not consistently associated with increased weight; behavioral factors - particularly exercise and alcohol consumption - were more strongly related to weight than simply the transition through menopause. And researchers investigating data from the SWAN study concluded aging - a period during which people tend to exercise less yet maintain the same amount of food intake - is likely responsible for the weight gain during middle age rather than menopause itself.

Eat less and exercise more

The SWAN researchers found, although midlife women tend to experience increases in weight and waist circumference over time, maintaining or increasing regular physical activity can help prevent or attenuate those gains. Regardless of the starting level, any decrease in activity level in midlife women was associated with higher weight over time, while increases in activity were associated with lower weight.

In a 5-year randomized clinical trial published in 2003 in Annals of Behavioral Medicine, researchers from the University of Pittsburgh investigated the effects of lifestyle intervention on weight gain during menopause. They found weight gain and increased waist circumference during the menopause period can be prevented in healthy women with a long-term lifestyle dietary and physical activity intervention.

The test subjects who were successful in fighting off an increase in weight followed a diet of approximately 1,300 calories per day and exercised to burn 1,000 to 1,500 calories per week. Keep in mind the number of calories you burn during exercise is dependent upon how much you weigh. For example, if you weigh 160 pounds, you can expect to burn about 500 calories per hour for high impact aerobics, backpacking, rowing or swimming; and 300 calories per hour for leisurely bicycling, golfing (carrying your clubs) or walking (3.5 mph)

Until science actually pinpoints the cause of weight gain and shifting during menopause, it seems exercise and a healthy diet are the best defenses against getting out of shape as you age. Gass sums it up, "We are moving toward greater obesity in the general population; so we all have to eat less and exercise more. Don't blame it all on menopause."

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