Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
Trying to lose weight after having a baby can feel overwhelming, especially while adjusting to the demands of breastfeeding and recovery. Many new mums wonder whether they can take weight loss injections while breastfeeding safely. With the rising popularity of medications like semaglutide (Ozempic or Wegovy), it’s a valid concern.
In Australia, over 60% of women are classified as overweight or obese by the time they reach middle age, with many struggling to manage weight gain after pregnancy. But when you’re breastfeeding, your health decisions affect not just you, but your baby too. Before considering weight loss injections, it’s important to understand the potential risks, what medical guidelines say, and what safer alternatives might look like during this phase.
While weight loss injections may seem like a convenient solution, they are generally not recommended during breastfeeding. This is a time when your body is still healing and your baby’s health is closely tied to your own. Here’s why experts urge caution.
Many medications are known to be excreted into breast milk and can be bioavailable to the infant. While many pose minimal risk, others, including synthetic hormones or appetite-regulating compounds found in some weight loss injections, may require caution or be contraindicated during lactation. This means your baby could be exposed to substances that haven’t been proven safe for infants. Because babies have immature organs, even low levels of these compounds could have a disproportionate effect on their development. Until more targeted data becomes available, this remains a valid concern.
Most weight loss injections, including newer medications like semaglutide, have not undergone clinical trials involving breastfeeding women. This gap in research means we can’t fully understand the risks, if any, these drugs pose to your baby or your milk supply. Without this vital safety data, using these injections is essentially a gamble, one that most medical professionals recommend avoiding.
The first year of life is crucial for growth; breastfed infants often double their birth weight by about 4 months.
Even trace amounts of certain substances in breast milk can impact a baby’s metabolic processes, feeding behaviours, and overall growth trajectory. Since weight loss injections alter hormone signalling in adults, there’s concern that these changes might indirectly affect a baby’s development. Until it’s proven otherwise, the safest course is to avoid unnecessary medication exposure during this formative stage.
Breastfeeding relies on a delicate hormonal balance, mainly prolactin and oxytocin, to produce milk and support bonding. Introducing weight loss injections, many of which target or mimic hormones, may disrupt this balance. For a new mum, this could mean unexpected changes in mood, sleep, or appetite regulation. These disruptions can also interfere with breastfeeding rhythms, making the journey more stressful than it needs to be.
Clinical trials for GLP-1 weight loss injections report side effects, including nausea, fatigue, and digestive issues. While these may be tolerable under normal circumstances, they can be especially difficult to manage while caring for a newborn. Fatigue, dizziness, and low appetite may affect your ability to breastfeed regularly or respond to your baby’s needs. Plus, these side effects can mimic or worsen symptoms of postpartum mood disorders, complicating recovery.
Weight loss injections suppress appetite, which can lead to decreased food intake and hydration—both crucial for maintaining a healthy milk supply. If you're not eating or drinking enough, your body may produce less milk, making breastfeeding more challenging. This can lead to early weaning, which may not align with your feeding goals.
While the uterus usually returns to its pre-pregnancy size within about six weeks, full recovery from childbirth often takes much longer. During this time, your body is still healing, and introducing medications that affect metabolism or hormone levels may disrupt that process. Recovery goes beyond physical healing; it also involves regaining emotional balance, sleep rhythms, and overall strength. That’s why focusing on gentle, sustainable strategies is especially important in the postpartum period.
Most medical guidelines err on the side of caution when it comes to prescribing weight loss injections to nursing mothers. In clinical settings, doctors often advise waiting until after weaning before considering pharmacological weight loss. Following these guidelines helps ensure the wellbeing of both you and your baby.
If you're aiming to shed postpartum weight while continuing to breastfeed, the good news is that sustainable, gentle methods can be just as effective and far safer for both you and your baby. Below are practical strategies that support weight loss without compromising milk supply or recovery.
A study found that diets rich in whole foods are associated with better weight management and improved overall health outcomes.
Choosing whole foods, like vegetables, fruits, lean proteins, whole grains, and healthy fats, nourishes your body and keeps you fuller for longer. These foods are naturally lower in added sugars and unhealthy fats, which can contribute to postpartum weight gain. By focusing on quality rather than restriction, you support both weight loss and milk production. In addition, whole foods tend to offer more fibre and nutrients that are beneficial for your baby’s development through breast milk.
Rather than meticulously counting calories, tuning into your hunger cues and serving smaller portions can go a long way in preventing overeating. Larger portion sizes can lead to consistently higher energy intake, which may contribute to weight gain over time. This makes portion awareness especially helpful during breastfeeding, when appetite naturally fluctuates.
Eating mindfully helps ensure you’re fuelling your body without overloading it. Over time, this simple habit can help retrain your appetite, reduce emotional or distracted eating, and support healthier eating patterns without the stress of strict dieting.
Hydration plays a big role in milk production, digestion, and overall metabolism, but it’s something many new mums unintentionally overlook. In fact, research suggests that exclusively breastfeeding mothers often have lower water balance, putting them at greater risk of dehydration. Thirst is also easy to confuse with hunger, which can lead to more snacking than your body really needs.
Keeping a water bottle nearby makes it easier to stay hydrated throughout the day. It can also help flush out lingering water retention from pregnancy, boost your energy, and even lift your mood.
Low-impact exercise, such as walking, is widely encouraged after childbirth, once you've been cleared by your GP. Starting with gentle movement like walking soon after hospital discharge can support circulation, mood, and gradual fat loss without overstressing the body.
A 20–30 minute walk with your baby in the pram not only aids physical recovery but also provides a valuable mental break, which is especially helpful in managing postnatal emotional shifts. Incorporating this routine into your day promotes endurance and strength over time, helping reduce the risk of chronic conditions, weight retention, and even postnatal depression. A gradual, personalised return to activity is key to protecting pelvic and musculoskeletal health as your body heals.
Meals high in fibre and protein have been shown to reduce hunger and the desire to eat, which may help lower overall calorie intake. Fibre aids digestion and keeps you fuller for longer, while protein helps preserve lean muscle mass as you lose weight. Incorporating foods like eggs, oats, legumes, lean meats, and leafy greens can make meals both satisfying and weight-friendly. These nutrients also support milk quality and sustained energy, which are important for breastfeeding mums.
Research shows that women who sleep less than 5 hours per night at 6 months postpartum are more than three times as likely to retain 5 kg or more of pregnancy weight by the end of their first year. Sleep deprivation can increase levels of cortisol, a stress hormone linked to weight retention and cravings for high-calorie foods. While uninterrupted sleep might be unrealistic with a newborn, naps and rest periods during the day can still make a difference.
The Australian Dietary Guidelines recommend limiting foods high in added sugar, salt, and unhealthy fats, especially when breastfeeding. Processed snacks and sweetened beverages can lead to blood sugar spikes, energy crashes, and unwanted weight gain. These foods are often low in nutrients and do little to support recovery or milk production.
If you’re still exploring the idea of weight loss injections, timing and preparation matter, especially after pregnancy. These medications are not typically the first line of action for new mums, particularly those who are breastfeeding. Here are key factors to consider before pursuing this path, to ensure it’s safe and supportive of your long-term health.
Wait until breastfeeding is fully stopped.
Most weight loss injections are not recommended during breastfeeding due to unknown effects on infants. To minimise risk to your baby, it’s best to wait until breastfeeding has completely ended before starting any weight loss injections. This ensures that your baby is no longer exposed to the medication through breast milk. It also gives your body time to naturally adjust after pregnancy and lactation. Post-weaning is often a safer, more stable window to consider medical weight loss support.
Monitor hormone levels and overall health first.
Complex hormonal changes, which can affect metabolism, weight retention, and appetite, occur postpartum. Before starting weight loss injections, it’s important to assess your overall health, including thyroid function, insulin sensitivity, and stress hormone levels. These underlying factors could be influencing your weight more than you realise.
A healthcare provider can help run blood tests to determine if hormone imbalances are at play. Addressing these first may reduce the need for medication altogether.
Start with non-invasive methods.
Guidelines from the Royal Australian College of General Practitioners recommend lifestyle changes as the first approach to postpartum weight loss. Non-invasive methods like dietary improvements, physical activity, and sleep regulation are safer and often effective, especially in the months following childbirth. These strategies not only promote weight loss but also support emotional wellbeing and energy levels.
Losing weight after pregnancy is a personal journey, and for breastfeeding mums, safety should always come first. While it’s understandable to want quick results, the truth is that most medical professionals advise against taking weight loss injections while breastfeeding, for good reason.
The postpartum period is a time for healing, bonding, and nurturing both yourself and your baby. There are many safe, effective ways to support weight loss while breastfeeding, from eating whole foods and staying active to getting enough rest and staying hydrated. If you're considering weight loss injections in the future, wait until you’ve weaned, check in with your health provider, and explore gentler methods first.
Your wellbeing matters, not just for your own health, but for the little one relying on you every day. Be kind to yourself, take it one step at a time, and know that progress doesn’t have to be rushed to be meaningful.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.