It is a common perception among women that oral contraceptives are associated with weight gain. However, Norplant and Depo-Provera are the only hormonal contraceptives that include specific statements that the expected change in weight is an increase, while the other contraceptives describe that there may be an increase or decrease in weight as a result of this drug. Since more than one million women used Depo-Provera and greater than 500,000 used Norplant, it is important to determine whether the use of these drugs can be expected to promote weight in women.
A group of researchers from Pennsylvania State University studied whether the use of progestational contraceptives caused an imbalance in energy regulation that lead to weight gain. Specifically, Pelkman et al. examined whether depot medroxy-progesterone acetate was associated with an increase in food intake or a decrease in resting energy expenditure (REE) in young women.
Body weight, REE, and 3-day food intake were measured in 20 normal-weight women during the follicular and luteal phases of two menstrual cycles. These measurements were taken either before a single injection of Depo-Provera or saline solution (control). The subjects were in the testing laboratory for four days. They consumed only foods and beverages that were provided during the first three days and were weighed in the morning on the first and fourth days; REE was measured before breakfast on the first day of each test session by indirect calorimetry.
Subjects consumed 4.3% more energy and expended 4.3% more energy at rest during the luteal phase as compared to the follicular phase of the menstrual cycle. Treatment with Depo-Provera or depot medroxyprogesterone acetate had no significant effect on food intake, body weight, or REE over the three-month testing period.
This experiment showed that although this phase of the menstrual cycle affected both energy intake and REE, Depo-Provera did not cause any short-term weight gain in young healthy, normal-weight women. Further research is needed to determine whether similar effects occur with different contraceptive hormones, over longer periods of time, and in other populations, such as overweight or obese women.