Birth control has been a hot topic when it comes to women’s health, hormone balance, and, specifically, weight management. 

Whether you love your form of birth control, are unsure which kind to choose, or are transitioning off the pill, we all have the same burning questions: Does birth control cause weight gain? Does birth control prevent weight loss? Can you be on birth control and still lose weight?

So…let’s talk about it! In this post, I want to quickly review the popular forms of birth control, what the research has to say about the effect on weight, and some overall considerations when it comes to birth control and your health.

Please note, this article is not intended to act as professional medical advice, but rather be a chill conversation looking at some research (it’s fun, I promise).

Birth control options:

When we think about birth control, the pill often comes to mind first, but here are quite a few options.

Hormonal birth control (HBC), is often referred to as “the pill.” It is a steroid drug that is used to override our natural hormone function. This prevents ovulation and therefore prevents pregnancy. Some might explain that the pill tricks the body into thinking you are already pregnant or acts like a “chemical menopause.” 

Specifically, HBC contains a synthetic version of estrogen and progesterone (the two major hormones involved in the menstrual cycle and sexual reproduction). These alternate versions inhibit the production of follicle-stimulating hormone and luteinizing hormone, which prevent ovulation.

HBC can actually include both estrogen and progesterone or just progesterone. The progesterone-only pill or the “mini-pill,” has fewer side effects for some women and can be used while breastfeeding. It can be less effective in some scenarios, especially when not taken consistently.

It can be considered a red flag that HBC prevents ovulation. This is obviously helpful to prevent pregnancy, but this means we don’t have the natural production of our sex hormones. Any hormonal imbalance can have a negative impact on your metabolism, mental health, mood, skin, etc. 

The pill can have some benefits for women though, like improved acne, lighter and less painful bleeds, and obviously preventing an unwanted pregnancy. 

Other forms of birth control include the IUD (intrauterine device), the Nuvaring, the birth control patch, the Depo-Provera shot, and the Nexplanon implant. They all have their unique pros and cons, which your OB-GYN can help you evaluate.

For the purposes of this article, we’ll be referring primarily to the hormonal birth control pill in order to answer our topic of discussion. The information we’ll be covering though can most likely be applied to these other forms of birth control when sex hormones are affected. What we do confidently know though is that the Depo-Provera shot specifically is proven to cause weight gain in most cases (about 10 pounds on average). 

For women who do not want their natural hormones disrupted or worry about potential weight changes, the copper IUD can be a great option.

Birth control and weight:

Women have become significantly more hesitant and frustrated about the HBC pill in recent years because of its potential for weight gain and/or preventing weight loss.

So is it really true though? Is being on the pill a guarantee for weight gain? Or is it saying goodbye to all hope of being able to lose weight?

Well, first, we have to understand there is a difference between anecdotal evidence (what your friends and Aunt Susan experienced) versus evidence backed by research. 

I’m not saying there’s no value in those word-of-mouth experiences, because here’s the thing: research can sometimes take a long time to catch up to what’s actually happening. However, let’s quickly review the research we do have available to us to help understand the relationship between birth control and weight. 

Review of the research:

Because weight gain is the most commonly reported side effect of the hormonal birth control pill, pharmaceutical companies do list it on the packaging. However, after several decades of research at this point, there is no conclusive evidence that HBC causes weight gain or prevents weight loss entirely. 

The largest known review examined 49 studies of the combined HBC pill and found no significant effect on weight. However, the authors did explain that there also wasn’t enough well-conducted research to be 100% sure of this conclusion. 

One study from 2020 was very interesting in that it investigated the ability of women to lose weight while on HBC over the course of 18 months. 

This study provided an opportunity to compare weight loss and maintenance between premenopausal women, both using and not using the pill. This was also the first study to compare the effect of HBC in women who were actively trying to lose weight.

In the end, it was observed that all the women, using HBC or not, were able to lose a significant amount of weight after 6 months with behavioral weight loss intervention. The important piece though was that those using HBC experienced regain of almost all the weight within a year later. The women who lost weight without using HBC were observed to avoid weight regain completely.

Why did this happen? The authors discussed a few potential influencers, including the potential impact of HBC on appetite, blaming this on the altered hormonal profile leading to increased intake. It was also discussed how women on HBC can have increased intake of high carbohydrate- and fat-based foods due to the synthetic progesterone.

It’s important to only take these findings with a grain of salt though, as future research is urgently needed. As of now, these are only really interesting preliminary findings and possible connections in this conversation.

So, what is the key takeaway from the research? There is just not enough solid evidence and variable data to say that birth control has a direct relationship with weight gain or prevention of weight loss. 

What the research does tell us is that it’s really difficult to control all the variables related to this question in order to uncover significant and clear information. For example, all women in further research need to have similar lifestyles, health status, nutrition intake, consistency taking HBC, etc. It’s not impossible to conduct more research but this may always be a somewhat gray area, along with other health and nutrition research.

Aside from the birth control pill itself, some might argue too that this pill-weight connection might come down to a natural human bias. For example, the average person can put on just over a pound of weight each year for most of their adult life, which incidentally aligns with when women start using contraception. This can be a harsh way of looking at things, but “weight creep” could be related to outside factors for some women too.

Other things to think about:

Even though the research doesn’t give clear answers, we do have other information to know this isn’t just all in our heads. For example, HBC can potentially change a woman’s body shape and composition in 3 different ways:

1. Muscle

In 2009, a research study found that oral contraception uses impaired muscle growth in young women. A more recent 2021 study also investigated this potential connection between birth control and muscle growth inhibition with very similar conclusions. 

This relationship found between women using HBC and decreased muscle mass makes sense though. We know that men have an easier time putting on muscle, mostly due to their increased amount of anabolic hormones (which tell the body to put on more muscle). Women have these hormones too, specifically DHEA, but those using HBC are found to have less of it. 

It’s explained in the research that what might be happening is that the progesterone in the HBC is fighting for the same binding sites as the hormones that signal muscles to grow. The results of this study aren’t definitive, but they’re a good starting point. 

2. Body composition

The pill might be changing the shape and body composition of women’s bodies too. How would this happen? 

Well, we already talked about the pill’s potential to inhibit muscle growth in women. This would definitely change body composition and also inhibit potential to burn fat with decreased metabolic demand.

The other contributor to this is the fact that HBC changes a woman’s natural hormone balance and this may alter where fat is stored in the body. Some research has argued that this can lead to an increased pear-shaped figure with increased subcutaneous fat. However, this is based on pretty outdated research that is over 30 years old. A more current study concluded that body composition changes in women long term were not significant. 

3. Water retention

It can definitely be common for women to report frequent bloating and water retention while on the pill. Ugh. 

While this isn’t exactly fat mass gain, it can make us feel as though our body is changing in size and affect the number we see on the scale from water weight.

Why does this happen? In short, estrogen can impact how we metabolize water and hold on to extra right before the time of the month for all women. Synthetic estrogen from the pill can be a tad dramatic with this process and tell the body to hold on to even more water. 

A few other considerations: 

Believe it or not, there are even more ways that the pill can indirectly affect a woman’s weight. 

Let’s consider the very real potential for nutrient deficiencies. Women taking oral contraceptives are known to have lower levels of folic acid, vitamin B12, vitamin B6, vitamin C, vitamin E, magnesium, selenium, and zinc. While having a deficiency of any of these is not a direct cause for weight gain or difficulty losing weight, it could be the start of a domino effect impacting our overall health status and how we feel day to day.

For example, vitamin B12 and magnesium are both key nutrients for our mood and mental health. HBC already has concerns for impacting some women’s mental health with higher rates of anxiety and depression, and this is nutrient depletion aside. And let’s be real, struggling with mental health can open the doors for weight gain OR weight loss.

Women also often experience increased appetite while on the pill. While there isn’t great research to be certain, we do know that estrogen helps regulate appetite in the hypothalamus and the pill can partially disrupt this.  

So, should you use birth control?

While the research is not conclusive to say that birth control should be avoided if you have weight concerns, it has been a common struggle for many women. If you have hesitations regarding HBC, you should definitely know that there are many alternative options to prevent pregnancy, including natural family planning. 

From my own personal standpoint, I think there has been a lot of attention drawn to this conversation of birth control when it comes to weight, metabolism, nutritional status, gut health, mental health, and so many other areas, and it has been a really beneficial thing. We have so many healthcare professionals going through the research and making trustworthy resources for women to truly understand the pros and cons of all forms of birth control in order to make an informed decision. 

This was not the case 20 or even 10 years ago. Many of us share an experience where birth control was started with very little insight or knowledge on the subject. It’s encouraging that we are more open to this discussion and digging deeper into how it may impact our health in a variety of areas, and not just related to weight.

If you want to transition off the pill:

Be sure to check out this article and always consult your physician for the best recommendations. Supporting your body with proper nutrients and other lifestyle factors will set you up to feel your best while your natural hormones resume. 

If you want to stay on the pill:

If the pill makes sense for you right now and you are doing well on it, you can still support a healthy metabolism and weight. Everything we talk about at myDietitian will help you do this as efficiently as possible. The highlights though are eating for stable blood sugar, regulating your hunger hormones, sleeping enough, supporting your gut health, and managing stress.

I wish we had more clear answers about birth control and weight loss, but in the end, always decide with your doctor what makes the most sense for your situation and continue to prioritize your overall health to minimize any potential side effects and weight changes. 

Ditching the diet mindset and focusing on your metabolic health is yet again going to be extremely helpful for this and set you up for success in the best way, whether on the pill or not. 

Elle, Metabolism Makeover Coach, RD