This study examined longitudinal changes in body composition, fat distribution, and energy balance in perimenopausal women. The researchers hypothesized that menopause would lead to increased total body fat and visceral adipose tissue (VAT) due to decreased energy expenditure (EE) and declining estrogen levels. The study followed 156 healthy women (103 Caucasian, 53 African-American) over four years, with annual measurements. Women were classified as postmenopausal if they had no menstruation for one year and follicle-stimulating hormone (FSH) levels >30 mIU/ml. Results showed that body fat and weight increased significantly only in women who became postmenopausal by year 4. All women gained subcutaneous abdominal fat (SAT) over time, but only those who became postmenopausal had a significant increase in VAT. Postmenopausal women also exhibited a significant decrease in serum estradiol. Physical activity decreased significantly two years before menopause and remained low. Dietary energy, protein, carbohydrate, and fiber intake were significantly higher three to four years before menopause onset compared with menopause onset. Twenty-four-hour EE and sleeping EE decreased with age, but the decrease in sleeping EE was 1.5-fold greater in postmenopausal women compared with premenopausal controls. Fat oxidation decreased by 32% in women who became postmenopausal. The study concluded that middle-aged women gain SAT with age, whereas menopause per se is associated with an increase in total body fat and VAT. Menopause onset is associated with decreased EE and fat oxidation, which can predispose to obesity if lifestyle changes are not made. The study highlights the importance of monitoring body composition and energy balance during the menopause transition, as well as the need for lifestyle modifications to prevent weight gain and visceral fat accumulation.This study examined longitudinal changes in body composition, fat distribution, and energy balance in perimenopausal women. The researchers hypothesized that menopause would lead to increased total body fat and visceral adipose tissue (VAT) due to decreased energy expenditure (EE) and declining estrogen levels. The study followed 156 healthy women (103 Caucasian, 53 African-American) over four years, with annual measurements. Women were classified as postmenopausal if they had no menstruation for one year and follicle-stimulating hormone (FSH) levels >30 mIU/ml. Results showed that body fat and weight increased significantly only in women who became postmenopausal by year 4. All women gained subcutaneous abdominal fat (SAT) over time, but only those who became postmenopausal had a significant increase in VAT. Postmenopausal women also exhibited a significant decrease in serum estradiol. Physical activity decreased significantly two years before menopause and remained low. Dietary energy, protein, carbohydrate, and fiber intake were significantly higher three to four years before menopause onset compared with menopause onset. Twenty-four-hour EE and sleeping EE decreased with age, but the decrease in sleeping EE was 1.5-fold greater in postmenopausal women compared with premenopausal controls. Fat oxidation decreased by 32% in women who became postmenopausal. The study concluded that middle-aged women gain SAT with age, whereas menopause per se is associated with an increase in total body fat and VAT. Menopause onset is associated with decreased EE and fat oxidation, which can predispose to obesity if lifestyle changes are not made. The study highlights the importance of monitoring body composition and energy balance during the menopause transition, as well as the need for lifestyle modifications to prevent weight gain and visceral fat accumulation.