If you have any questions about this information, you can contact the Drugs in Breastmilk team through their Facebook page or on druginformation@breastfeedingnetwork.org.uk.
You can use protein or meal replacement shakes and isotonic or electrolyte drinks occasionally whilst you are breastfeeding. However, you should avoid those containing high caffeine levels, other stimulants, or other herbal supplements.
Avoid consuming more protein than your body needs.
We don’t have evidence available for herbal or health remedies containing multiple ingredients.
If you would like to exercise, usual exercise will not affect your milk supply.
Very low-calorie diets are not recommended while you are breastfeeding.
In this factsheet:
Recovering From Illness
It is not uncommon to experience sick bugs, viruses or various back-to-back illnesses. Sometimes you can become quite unwell and have a sustained period of illness which can result in feeling run down and completely depleted.
While a balanced diet and a vitamin D supplement is all you usually need during recovery, you may choose to take a multivitamin as a bit of a “boost”. Any standard multivitamin supplement that doesn’t contain high doses, or additional herbal remedies as well, can be taken when breastfeeding. See our factsheet on vitamins and supplements for more information.
While you’re unwell, you may not be able to eat well. Staying hydrated is important and usually the main concern. If you’re unable to eat as well as usual for a longer period, you may be wondering if meal replacement shakes, or oral nutritional supplements (ONS) prescribed by a healthcare professional are compatible with breastfeeding. While these would not usually be needed if you are eating a balanced diet, you can have meal replacement shakes or ONS alongside usual food if it helps you to keep your energy up and to meet your daily recommended energy (calorie) intake.
Exercise and Building Muscle
Exercising after your pregnancy
Getting back to your usual activities, hobbies and fitness after your pregnancy can be a great way to feel good. There is no need to rush into getting back to everything though, and it’s important to go at your own pace. It’s best to start slowly and build up gently in the weeks and months after birth. You can read more about exercising after your child arrives from NHS Inform – Getting active after the birth and Keeping fit and healthy with a baby which also has information on looking after your pelvic floor. It is important to make sure you stay well hydrated whilst exercising. You might find it helpful to breastfeed your baby just before exercising, if you can. Activity and exercise won’t affect your milk supply.
Protein
You may want to increase your protein intake if you’re exercising more, weightlifting or if you are prioritising your protein intake in your daily nutrition. Generally, while breastfeeding you will need 53-56g of protein per day. The usual daily recommended intake of protein is compatible with breastfeeding.
You can use supplements and protein shakes containing additional protein provided by milk, pea, rice, soya or hemp protein, at usual daily recommended amounts whilst breastfeeding.
Take care not to consume very high amounts of protein that are beyond your individual needs, as this can put a strain on your kidneys. You can find out more about protein needs on the British Nutrition Foundation website, and from the government on daily recommended dietary requirements. Your healthcare professional, or dietician can help if you’re unsure of your daily needs.
While you may find protein shakes (pre-made or simple protein shake powder that you mix) useful as part of your routine, you should avoid muscle building powders while breastfeeding, especially those with “performance enhancers”, caffeine or those with lots of ingredients. Some of these contain very high amounts of caffeine which would not be compatible with breastfeeding. Some of the other ingredients that may be included often have no evidence of safety while breastfeeding. The Drugs in Breastmilk Service is unable to look up long lists of active ingredients that are sometimes in these products as there is no data available.
You can read more about caffeine intake while breastfeeding on the breastfeeding and diet NHS website page.
Isotonic drinks and electrolyte drinks
You can use isotonic drinks and electrolyte sachets when breastfeeding. They are usually used to prevent dehydration when you’re unwell, including when you have vomiting or diarrhoea. They are not needed to maintain hydration when you are otherwise fit and well. Some products available aimed at use while exercising also contain performance enhancers including stimulants, caffeine and other ingredients. There is no data available on the safety of such products containing multiple ingredients. Products containing performance enhancers or caffeine levels that will take you over 200mg per day should be avoided while breastfeeding.
For more information on dehydration, see the Dehydration – NHS page.
Losing Weight
Once your baby has been born, you may be thinking about losing weight. However, it is important that you are kind to yourself and recognise what your body has been through. Pregnancy is a huge undertaking on your body. It places a large demand on your health and reserves. It is common to gain some weight in pregnancy. Some people may gain weight in the immediate post-partum period too. Breastfeeding can make you feel thirsty and hungry; sleep deprivation can be very challenging, and the resulting lack of energy can see you reaching for a boost in the form of a snack, or relying on higher energy, easier foods that are quick to “grab and go.”
You may feel more hungry than usual in the early months of breastfeeding. This can lead to cravings for sweet or starchy foods. Some people find that eating protein-rich snacks instead can help manage this hunger and stabilise their blood sugar levels better.
Whilst it is a good idea to maintain a healthy weight, and important to stay active and eat a nutritionally balanced diet if you can, it’s not always easy when you have a new baby or young child to care for. You need your energy at this time, so it is important not to deprive yourself of too many calories. Losing weight slowly, with sustainable lifestyle changes, is likely to be more achievable.
You may not be focusing on weight loss but instead working on improving your strength and energy levels though nutrition. This may still take the form of a “diet” and might lead to you losing weight.
Breastfeeding reduces your risk of being overweight and developing type 2 diabetes, as well as reducing your baby’s risk of being overweight in adulthood or being diagnosed with diabetes.
Regardless of your reasons for coming to this section, self-compassion, time, and a slow and steady approach are the way forward. If you are unsure, your pharmacist, GP or other healthcare professional at your GP practice can discuss your concerns with you.
Nutrition
Food, nutrition and diet can be an emotive topic. The food industry is changing the way we eat and impacting our access to affordable, nutritious foods. Whether you are interested in your energy intake, your nutrient intake (macro and micronutrients) or reducing the amount of processed and ultra processed foods you eat while improving your health, there is a confusing amount of information available. Below are some resources that may help you decide what sustainable changes you want to make to the way you eat. The calorie number and nutritional information discussed below are assuming you are an average height. If you are very short or very tall, your daily needs should be tailored to your requirements. Your daily calories needs may be higher or lower than described below.
How many extra calories does breastfeeding actually require?
Depending on the resource you’re reading and whether your baby’s only, or main, source of nutrition is breastmilk, or if they’re a toddler feeding only a couple of times a day, this number varies! Somewhere between 300-500 calories is often quoted. This means your daily energy intake in calories may be around 2000-2500 calories.
Low calorie diets
Unless you are being supported by a specialist weight loss centre who are aware you are breastfeeding and are ensuring your nutritional needs are met, you should not undertake low or very low-calorie diets of less than 1400 calories per day. Restricting your energy intake this severely may impact on your breastmilk supply and is unlikely to be sustainable in the long run.
Weight loss shakes
While most meal replacement shakes, including lower calorie or usual calorie levels, are compatible with breastfeeding, they should not form the main part of your diet. Avoid shakes which contain additional supplements including caffeine, stimulants or herbal weight loss remedies. These shakes are usually ultra-processed, and many have higher levels of sugar which can spike your blood sugar levels, ultimately causing you to feel hungry again sooner. Sometimes, being a parent and juggling life can be busy though and occasionally having a meal replacement shake rather than nothing is ok.
If you need oral nutritional meal replacements for a medical reason, your healthcare professional will supervise this and support you with any questions you may have.
Dr Chris Van Tulleken talks more about ultra processed foods in his book Ultra Processed People.
Medications used to aid weight loss
You can learn more about weight loss, obesity and medicines used in weight loss on the Obesity treatments – NHS page.
GLP-1 Agonists
You may be wondering about the use of weight loss injections (GLP-1 agonists, including Liraglutide as Saxenda®, Semaglutide as Wegovy® and Tirzepatide as Mounjaro®) available on the NHS and privately.
Guidance from the MHRA published in June 2025 states “GLP-1 medicines should not be taken by people who are breastfeeding. This is because there is not enough safety data to know whether taking a GLP-1 medicine can cause harm to the baby. If you have any concerns, speak to a healthcare professional.”
However, in April 2026, the patient information leaflet for Tirzepatide as Mounjaro® was updated to state “Tirzepatide passes into breastmilk in very low amounts and is not expected to be absorbed by a breastfed newborn/infant. If you are breast-feeding or are planning to breast-feed, talk to your doctor before using or continuing to use this medicine.”
If you have been offered or are considering taking a GLP-1 medicine for weightloss and are making a decision about whether to take it and how this will impact your breastfeeding journey, or if you have been taking one of these medicines whilst breastfeeding, you can contact the Breastfeeding Network Drugs in Breastmilk team to discuss this. For general support with breastfeeding or stopping breastfeeding, you can also contact the National Breastfeeding Helpline.
If you are considering taking a GLP-1 agonist, please see our diabetes factsheet, where you can find more important information on these medications and their possible side effects.
Other weight loss medications
Available over the counter as Alli® 60mg, and Orlos® 60mg or by prescription only as own brand and Xenical® 120mg capsules.
Orlistat works by blocking gastrointestinal enzymes which manage the breakdown of fats in the food you eat. This prevents your body from absorbing the fat in your meal. Instead, it passes through your gut, often causing unpleasant side effects which include diarrhoea if you have consumed too much fat in a meal.
It is usually taken three times a day with your meals. If you miss a meal or it contains no fat, the dose of orlistat should be omitted.
Orlistat not only blocks the absorption of unwanted dietary fats, but essential fat-soluble vitamins including vitamin D.
Only very small amounts of orlistat are likely to enter your milk. Orlistat is not expected to affect your child or your milk supply.
If you decide that orlistat is right for you to take while breastfeeding, you should take a multivitamin containing vitamin D at a separate time to your meals and orlistat doses. If you have no fat in your breakfast, you could take your multivitamin at breakfast, omitting that dose of orlistat. Your multivitamin should be taken at least 2 hours after your last dose of orlistat, or just before bed.
Orlistat is expected to cause diarrhoea. If you take an oral contraceptive, you will need to use an additional barrier method. Alternatively, you could discuss changing your contraceptive to a non-oral choice with your healthcare professional. See our factsheet on contraception for more information.
Orlistat could affect the absorption of other medication too. You should discuss this with your pharmacist or healthcare professional.
Fibre, fibre laxatives and nutritional fibre are considered compatible with breastfeeding. However, there isn’t much evidence that these help you lose weight. Dietary supplements marketed as weight loss supplements have limited evidence of benefit.
Daily fibre is recommended for your gut health.
You can read more about how to get more fibre into your diet on the NHS webpage.
Related Factsheets
Bibliography
Click to see bibliography
- British National Formulary – https://bnf.nice.org.uk/
- Drugs and Lactation Database (LactMed®) - https://www.ncbi.nlm.nih.gov/books/NBK501922/
- Specialist Pharmacy Service: https://www.sps.nhs.uk/
- NHS medicines website: https://www.nhs.uk/medicines/
- E Lactancia website: https://www.e-lactancia.org/
- NICE Clinical Knowledge summaries: https://cks.nice.org.uk/topics/
- Hale T. W. Medications in Mothers Milk. www.halesmeds.com
- Dr Wendy Jones, Breastfeeding and Medication website: https://breastfeeding-and-medication.co.uk/
- Government Dietary Recommendations Government recommendations for energy and nutrients for males and females aged 1 – 18 years and 19+ years. Dietary Requirements Published August, 2016
https://www.gov.uk/government/publications/mhra-statement-on-products-containing-cannabidiol-cbd
©The Breastfeeding Network. Version 1.0. First published July 2026.
You may also like
Patient information leaflets – what do they mean?
Read more
Introduction to the Safety of Drugs passing through Breastmilk
Read more
