Pumping burns calories because your body uses energy to produce milk, similar to breastfeeding, but direct breastfeeding often burns more calories due to increased muscle engagement and activity, making it potentially faster for weight loss, though results vary greatly by individual metabolism, milk output, and activity levels; many mothers find weight loss occurs more steadily or even stalls until they stop lactating, as the body prioritizes milk production.
Continue to eat healthy while pumping and breastfeeding
Consume at least 1800 calories/day of nutrient-rich foods while you're producing breastmilk. By pairing a healthy diet with breastfeeding or pumping, healthy weight loss will come naturally.
Since a breast pump mimics a baby sucking at the breast, your body responds similarly when it comes to the metabolic response. But while both pumping and breastfeeding burn calories, breastfeeding tends to be more efficient and therefore moms who breastfeed do it more often, burning more calories in the long run.
While both activities require energy, breastfeeding involves more physical effort, such as muscle engagement and increased calorie expenditure due to the body's milk production process. Pumping mainly burns calories through the physical action of pumping, but generally at a lower rate.
On average, breastfeeding mothers burn an additional 300 to 500 calories per day. Pumping breast milk, while not identical to direct breastfeeding, also contributes to this calorie expenditure.
Breast milk is roughly 20-22 calories per oz. So if you're making 42-44oz, you're burning approximately 840-970 calories (ish). There is definitely some variation with different people's milk, but this could give you a rough estimate of what you need on top of maintenance.
Negative experiences included pain, increased milk supply concern, reduced time for other activities and frustration with inconsistent advice from clinicians about pumping.
The "4-4-4 rule" for breast milk is a simple storage guideline: fresh milk is good for 4 hours at room temperature (up to 77°F/25°C), for 4 days in the refrigerator (39°F/4°C or colder), and up to 4-6 months (or longer) in a standard freezer (0°F/-18°C). It's a handy mnemonic, though some organizations like the CDC recommend up to 6 months in the freezer and the AAP up to 9 months, with deeper freezers offering even longer storage.
A sustainable and healthy rate of weight loss during this time is about one to two pounds (0.5-1 kg) per week. You can realistically expect to lose around 20 to 30 pounds (9 to 14 kg) by six months postpartum, depending on your pre-pregnancy weight, overall health, and lifestyle choices.
For exclusively pumping parents: Aim for 8-10 pumping sessions per day, especially in the early weeks. This allows you to pump every 2-3 hours during the day, with one longer stretch at night (e.g., 4-5 hours).
Rule #2: The Breast Milk Storage Guidelines.
The 4-4-4 Rule. Or the 6-6-6 rule. Basically, breast milk is good at room temperature for 4 or 6 hours, in the refrigerator for 4 or 6 days, and in the freezer for 4 or 6 or 12 months. Different professional organizations have varying recommendations.
The 3-3-3 rule for weight loss is a simple, habit-based method focusing on three key areas: 3 balanced meals a day, 3 bottles (or ~1.5L) of water by 3 PM, and 3 hours of physical activity per week, aiming for consistency over complex diets. It simplifies fat loss by establishing rhythm through consistent eating, adequate hydration to support metabolism, and regular movement, promoting sustainable health without intense calorie counting or restrictive rules, says Five Diamond Fitness and Wellness, Joon Medical Wellness & Aesthetics, and EatingWell.
Weight Loss in Lactation
The hardest months of breastfeeding are typically the first month, due to latch issues, constant feeding (cluster feeding), and supply concerns as your body adjusts, and around 3 months, often called the "three-month crisis," marked by fussiness, distractions, and changes in sleep patterns that can make feeds harder. While the first few weeks are intense, overcoming these challenges often makes things much smoother as you and your baby find your rhythm.
The 30-30-30 pumping method is a power pumping technique to increase milk supply by mimicking cluster feeding: pump for 30 minutes, rest for 30 minutes, then pump for another 30 minutes, signaling your body to make more milk. This time-consuming, one-hour block aims to boost prolactin levels, with results often seen in 3-7 days, and is done once or twice daily as part of your regular schedule, replacing standard sessions.
When it comes to your own weight loss while breastfeeding, it's not unusual. Women who breastfeed burn an additional 500 to 700 calories per day, which can lead to weight loss.
Rapid postpartum weight loss may be caused by fluid loss, hormonal shifts, and breastfeeding, which burns extra calories. However, if you're losing weight quickly without trying, it could be a sign of an issue like postpartum thyroiditis or another health condition.
The 5-5-5 rule is a postpartum guideline for the first 15 days of recovery, emphasizing rest to help the new parent heal and bond with the baby, by spending 5 days in bed, followed by 5 days on the bed, and then 5 days near the bed, gradually increasing activity while prioritizing rest, nourishment, and self-care over chores or visitors. It's a framework for creating boundaries and slowing down to prevent overexertion, though individual recovery needs should guide the pace.
The average cumulative weight loss at 6 months post‐partum was 2.561 kg (SD 4.585), increasing at 12 months (3.066 kg; SD 5.098) and decreasing at 18 months (1.993 kg; SD 5.340), being 1.353 kg (SD, 5.574) at 24 months post‐partum.
At around 6 weeks, many moms introduce the pump and follow the Magic 8 method — pumping 8 times in 24 hours to help build and maintain milk supply.
You can store breast milk in a sterilised container or in special breast milk storage bags: in the fridge for up to 8 days at 4C or lower (you can buy fridge thermometers online) – if you're not sure of the temperature of your fridge, or it is higher than 4C, use it within 3 days.
If your mixed feeding involves exchanging some breastfeeds for baby formula, then your baby will not receive as many benefits as they normally would if they were exclusively breastfed. As such, their immune system may not be as well protected from certain infections1.
Many moms get the most milk first thing in the morning. Pump between breastfeeding, either 30-60 minutes after nursing or at least one hour before breastfeeding. This should leave plenty of milk for your baby at your next feeding. If your baby wants to breastfeed right after breast pumping, let them!
A study conducted by researchers from Cambridge, London and Paris found that formula fed babies seemed to smile more and cry less than breast fed and combination fed babies. The study also showed that formula fed babies settled to sleep more easily.