Causes of Rapid Weight Loss After Pregnancy

A new mom breastfeeding her baby

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After you have your baby, you will typically lose a little weight right away as the body adjusts and sheds fluids. After that, weight loss varies from person to person. Many women worry about not being able to lose all the weight they gain. However, some people quickly lose more weight than is desirable after giving birth. Rapid or excessive postpartum weight loss may occur due to lifestyle factors or from a medical issue.

Typical Postpartum Weight Loss

Immediately after your baby is born, you will lose about 10 to 12 pounds. That's a combination of your newborn's weight plus the placenta and the amniotic fluid. Then, during the next few days, you will lose about 5 more pounds of water weight. After that, it's typical and healthy to lose approximately 2 pounds a month for the next six months.

Note that rates of weight loss will be different for each postpartum person depending on their lifestyle, metabolism, whether or not they are breastfeeding (breastfeeding tends to increase weight loss), and other personal health and genetic factors.

Losing too much weight too quickly is not good for you or your baby. Excessive postpartum weight loss can leave you feeling exhausted and run down. You may also end up with a low breast milk supply or with breast milk that's lacking in the nutrients that your baby needs.


If you are breastfeeding, you may lose weight more quickly than if you don't breastfeed. The hormones that your body releases when you breastfeed cause muscle contractions in your uterus. So, each time you breastfeed your baby, your uterus contracts and shrinks down. By six weeks after childbirth, your uterus will be back to the size it was before you became pregnant

It takes about 500 extra calories a day to make breast milk. You get those extra calories from the foods that you eat every day and the fat that is already stored in your body. Using up those fat stores helps you to lose weight gained in pregnancy faster. So, if you are losing weight too quickly or losing more weight than desired, you may not be eating enough to make up for the calories used by your body to make breastmilk.

What to Do

Be sure to give your body enough food to fuel breastfeeding your baby. Eating lots of healthy snacks can help you get enough calories while breastfeeding. Making eating regularly a little easier by stocking up on nutritious pre-made or easy-to-prepare foods, especially those that you can eat with one hand. Ideas include cheese and crackers, hard-boiled eggs, peanut butter and jelly sandwiches, fresh fruit, and granola with yogurt. Aim for items with lots of protein.

Not Consuming Enough Calories

The demands of motherhood can make it easy to skip meals—you may be too tired to think about your own meals but, as noted above, it's important to eat enough. It takes a good amount of energy to breastfeed and make a healthy supply of breast milk. To get that energy, make sure that you're eating a variety of healthy foods to provide you with all the nutrients and calories that you need. By the same token, it's recommended to avoid dieting while breastfeeding.

Remember that between taking care of a new baby, other children, a home, and/or paid work, it's easy to get caught up in all you have to do and forget about taking care of yourself. If you're losing too much weight, take a minute to think about how much you're doing and whether you are taking time for your own nutrition. Aim to eat right, drink plenty of fluids, and get enough rest.

What to Do

Taking the time to have appetizing and accessible snacks on hand can help you get into the habit of boosting your caloric intake. Additionally, ask for and accept help from loved ones. Getting support with grocery shopping (or sign up for a delivery service), having a partner, friend, or grandparent provide more baby care, or receiving meals from loved ones and neighbors can help you make more time for meals.

Postpartum Thyroiditis

Postpartum thyroiditis (PPT), which is inflammation of the thyroid, is a health condition that can cause excessive weight loss, shakiness, palpitations, difficulty sleeping, restlessness, eye problems, exhaustion, and an overabundant supply of breast milk. The condition is relatively rare, impacting around 5% of postpartum people in the year after childbirth.

People with a personal or family history of thyroid dysfunction and those with Type 1 diabetes are at elevated risk. Some research indicates a link to underlying autoimmune disorders as well. Signs and symptoms usually present between one and six months postpartum and may progress from weight loss to eventual weight gain. The condition often resolves by around one year postpartum but may remain long-term in some women.

What to Do

If you are experiencing any of these symptoms and think you may have an overactive thyroid, call your doctor. There are treatment options that are safe for breastfeeding mothers.

Postpartum Depression

Tiredness and mood swings are common during the postpartum period. However, sometimes these issues magnify and become postpartum depression (PPD). Signs and symptoms include changes in weight or appetite, loss of interest, depressed mood, feelings of inadequacy, guilt, or worthlessness, fatigue, sadness, restlessness, and low energy.

This condition tends to develop within several weeks of delivery. People with PPD may lose weight because of a drop in interest in eating and/or preparing food. Tiredness or apathy may make you less likely to eat as well.

What to Do

If you are experiencing any PPD symptoms, or are just feeling off, it's important to seek help from a physician—and your loved ones. There are many effective treatment options, including cognitive-behavioral therapy and antidepressant medications (be sure to discuss with your doctor before taking any medications, particularly if you are breastfeeding). The support of friends and family is crucial for recovery as well.

A Word From Verywell

Often, excess or rapid postpartum weight loss is due to lifestyle issues and the pressures of new parenthood (like being too tired to eat), other times there may be a health concern that needs treatment. Either way, help is out there. So, if you're worried about losing too much weight, contact your doctor.

Depending on your weight before you become pregnant, how much weight you gained during your pregnancy, if you are breastfeeding, and your overall health, your doctor can let you know how much weight loss is healthy for your situation. Your medical provider can also help you make a plan for reaching and sustaining a healthy weight—and get you treatment if a medical issue is the cause of your weight loss.

2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Baker, Jennifer L., Gamborg, Michael, Heitmann, Berit L, et al. Breastfeeding reduces postpartum weight retention. Am J Clin Nutr. 2008;88 (6): 1543-1551. doi:10.3945/ajcn.2008.26379

  2. Di Bari F, Granese R, Le Donne M, Vita R, Benvenga S. Autoimmune abnormalities of postpartum thyroid diseasesFront Endocrinol (Lausanne). 2017;8:166. doi:10.3389/fendo.2017.00166

Additional Reading
  • American Academy of Pediatrics. New Mother’s Guide To Breastfeeding. Bantam Books, 2011.

  • Lawrence RA, Lawrence RM. Breastfeeding A Guide For The Medical Profession Eighth Edition. Elsevier Health Sciences, 2015.

By Donna Murray, RN, BSN
Donna Murray, RN, BSN has a Bachelor of Science in Nursing from Rutgers University and is a current member of Sigma Theta Tau, the Honor Society of Nursing.