Why Hormonal Birth Control Can Reduce Weight-Loss Success in Women

Recent research presented at ObesityWeek uncovered an interesting pattern. Women who used combined hormonal contraceptives lost less weight in behavioral weight-loss programs than those who didn’t. This study sheds new light on how synthetic hormones might influence weight control, appetite, and motivation during lifestyle interventions.

Researchers observed 59 women aged 18 to 60 with body mass indexes ranging from 27 to 46 kg/m². Twelve participants used combined hormonal contraceptives throughout the year-long trial. The rest followed the same method of contraception they were already using.

Freepik | Hormonal birth control users lost significantly less weight than non-users.

Participants joined one of two structured weight-loss programs:

1. A 4:3 intermittent fasting plan, limiting calorie intake by 80% on three nonconsecutive days per week.
2. A daily caloric restriction plan, cutting about 34% of daily calories.

Both groups received behavioral support sessions and were encouraged to reach 300 minutes of moderate-to-vigorous activity per week.

Results That Got Everyone Talking

Although both groups lost weight, differences emerged over time. Women using hormonal birth control saw an average reduction of 2.2 kilograms, while those not using it averaged 7.1 kilograms of weight loss. That’s a noticeable gap of almost five kilograms between the groups.

When looking at calorie reduction, the contrast remained clear. The control group maintained about a 10% decrease in calorie intake, while those using combined hormonal contraceptives averaged just 3.5%. This pattern hints that synthetic hormones may subtly affect appetite regulation and calorie restriction.

Physical Activity Findings

Freepik | Despite different weight loss, exercise motivation was maintained or boosted.

Interestingly, both groups boosted their weekly exercise, with the birth control group logging about 13 minutes more per week. This suggests that motivation to stay active wasn’t reduced, despite differences in weight-loss outcomes.

The extra activity highlights that factors beyond exercise, such as hormonal influences, may play a role in weight management.

Future Implications for Health Strategies

These findings point toward an important takeaway. Hormonal contraceptives may influence how the body responds to calorie control and weight-loss efforts. According to Dr. Adnin Zaman from the University of Rochester Medical Center, more research is needed to understand how synthetic estrogen and progestins affect hunger and metabolism.

Further studies could lead to improved obesity treatments and more personalized contraceptive counseling. As science continues to connect hormones and weight regulation, awareness becomes crucial to supporting healthier and more effective lifestyle programs.