Researchers gave female mice birth control pills while feeding them a high-fat diet to see what would happen. The mice taking birth control pills gained less weight and their bodies handled sugar better than mice that didn’t take the pills. However, the study also found that the birth control pills may have caused more inflammation in the liver. This mouse study suggests birth control pills might affect how our bodies store fat, but more research is needed before we know if these results apply to women.

The Quick Take

  • What they studied: Whether birth control pills containing ethinylestradiol and drospirenone could prevent weight gain and liver problems in female mice eating a high-fat diet
  • Who participated: 80 female mice that were 80 days old (roughly equivalent to young adult mice). Half ate normal food and half ate high-fat food. Within each diet group, some received birth control pills daily and some didn’t.
  • Key finding: Female mice taking birth control pills while eating high-fat food gained significantly less weight and body fat than mice not taking the pills. They also maintained better blood sugar control. However, their livers showed more signs of inflammation despite having less fat buildup.
  • What it means for you: This mouse study suggests birth control pills might help prevent weight gain from unhealthy eating, possibly by changing how the body stores fat. However, this is early research in animals only—we don’t yet know if this applies to women, and the liver inflammation finding raises questions about potential side effects that need further study.

The Research Details

Scientists divided 80 female mice into four groups. Two groups ate normal food (one with birth control pills, one without), and two groups ate high-fat food (one with birth control pills, one without). Every day for 65 days, the mice either received birth control pills or water through a feeding tube. The researchers then measured how much weight the mice gained, how well their bodies handled sugar, and examined their liver tissue under a microscope to look for fat buildup and inflammation.

This type of study is called a controlled experiment because the scientists carefully controlled what each group ate and whether they received the medication. This approach helps researchers understand cause-and-effect relationships. By comparing mice eating the same diet with and without birth control pills, they could see what the pills specifically did.

The researchers also looked at specific genes in the mice’s brown fat tissue (a special type of fat that burns calories to create heat) to understand how the birth control pills might be working at a biological level.

Animal studies like this one help scientists understand how medications affect the body before testing them in humans. By using mice, researchers can carefully control all the variables and examine tissues directly. This study is important because birth control pills are used by millions of women worldwide, so understanding their effects on weight and liver health matters for public health.

This study was conducted in a controlled laboratory setting with careful measurement of outcomes, which is a strength. However, there are important limitations: the study used mice, not humans, so results may not apply directly to women; the sample size and specific details about the mice weren’t fully described; and the journal’s impact factor wasn’t provided, making it harder to assess the publication’s prestige. The findings suggest birth control pills might have both benefits (less weight gain) and potential concerns (more liver inflammation) that would need careful evaluation in human studies.

What the Results Show

Mice taking birth control pills while eating high-fat food gained significantly less weight and accumulated less body fat compared to mice eating the same diet without the pills. This weight-loss effect was substantial and consistent throughout the 65-day study.

The birth control pill-treated mice also showed better glucose tolerance, meaning their bodies handled blood sugar more effectively. This is important because poor glucose control is linked to diabetes and other health problems.

When researchers examined the brown fat tissue (the type of fat that burns calories), they found that mice taking birth control pills had increased activity of two genes called Prdm16 and Ucp-1. These genes are responsible for making brown fat work harder to burn calories and produce heat, which may explain why these mice gained less weight.

Mice taking birth control pills also had less fat buildup in their livers compared to mice not taking the pills, which is generally considered a positive finding since fatty livers can cause health problems.

Despite having less fat in their livers, the mice taking birth control pills showed concerning signs of liver inflammation. Their liver tissue contained more inflammatory cells and had higher levels of a protein called IL-1β, which is a marker of inflammation. This suggests that while the birth control pills prevented fat accumulation in the liver, they may have triggered an inflammatory response that could potentially be harmful over time.

Previous research has shown that estrogen (the main hormone in birth control pills) affects how the body stores fat and uses energy. This study adds to that knowledge by showing that the specific combination of hormones in these birth control pills may activate brown fat tissue, which burns calories. However, the finding about increased liver inflammation is somewhat unexpected and suggests that the hormonal effects are complex—helping in some ways (preventing weight gain) while potentially causing problems in others (triggering inflammation).

This study has several important limitations: First, it was conducted in mice, not humans, so we cannot assume the same effects would occur in women. Second, the researchers gave the birth control pills through a feeding tube rather than as a pill, which may not perfectly mimic how women take the medication. Third, the study lasted only 65 days, which is relatively short compared to how long women typically use birth control pills. Fourth, the study didn’t examine other potential effects of the birth control pills on different organs or systems. Finally, the increased liver inflammation found in the study raises questions that weren’t fully explored—we don’t know if this inflammation would get worse over time or cause actual liver damage.

The Bottom Line

Based on this mouse study alone, we cannot make recommendations for women. This research suggests that birth control pills might affect weight gain and metabolism, but human studies are needed to confirm whether these effects occur in women and whether the liver inflammation finding is a real concern. Women currently using birth control pills should not change their behavior based on this single animal study. If you’re concerned about weight gain or liver health related to birth control, discuss these concerns with your doctor, who can review your individual situation and the full body of evidence.

This research is most relevant to: (1) Women considering birth control pills who are concerned about weight gain, (2) Researchers studying how hormones affect metabolism and weight, (3) Healthcare providers prescribing birth control pills, and (4) People interested in understanding how medications affect the body. This study should NOT be used by women to make decisions about starting, stopping, or changing birth control pills without consulting their doctor.

This is a mouse study, so there is no realistic timeline for human benefits or side effects. If similar research were conducted in humans, it would likely take months to years to see measurable changes in weight and metabolism, and longer to assess potential liver effects. Any human studies would need to be carefully designed and monitored by medical professionals.

Want to Apply This Research?

  • If you use birth control pills and want to monitor your health, track your weight weekly (same time of day, same scale), energy levels daily (1-10 scale), and any digestive changes. Also note any unusual fatigue or abdominal discomfort, which could indicate liver issues.
  • Use the app to set reminders for taking birth control pills at the same time daily, log your meals to monitor diet quality (since the study involved high-fat diets), and track physical activity. This helps you maintain consistent medication use while building healthy habits that support overall wellness.
  • Create a monthly health dashboard showing weight trends, energy patterns, and any symptoms. Share this data with your healthcare provider during regular check-ups to ensure your birth control choice is working well for your individual health profile. Set quarterly reminders to discuss any concerns with your doctor.

This research was conducted in mice and has not been tested in humans. The findings do not apply directly to women and should not be used to make decisions about birth control use. If you are taking or considering birth control pills and have concerns about weight gain, liver health, or any other side effects, please consult with your healthcare provider. Do not start, stop, or change your birth control medication based on this study without medical guidance. This summary is for educational purposes only and is not medical advice.