What Are The Reasons For Weight Gain After Surgery? Ways To Lose Weight

From stress to food habits - learn what’s causing that post-surgery weight gain.

Reviewed by Garima SinghGarima Singh, MSc, DNHE, DDHN
By Priyanka SadhukhanPriyanka Sadhukhan, MSc (Nutrition), Certified Diabetes Educator  • 

If you are gaining weight rapidly, one of the major reasons for it could be your recent surgery. This is due to the fluid retention that happens in the follow-up period. Weight gain after surgery can be handled by following a few measures. Mary Sabat, RDN, LD, CPT, says, “It is not unusual to gain weight after surgery, as the body needs time and energy to recover from the surgery.”

Weight gain is commonly observed post-pregnancy, especially after undergoing a C-section. To put things in perspective, here is a staggering stat for you. The Pregnancy Risk Assessment Monitoring System (PRAMS) suggests that weight gain post-pregnancy has sharply risen by 70% over the last few years (1).

Even a small procedure like a tonsillectomyi  XSurgical removal of both tonsils from the throat to treat obstructive sleep apnea, recurring tonsillitis, and throat infections. can make you put on weight. In this article, we have listed the six major reasons for postoperative weight gain and some dietary measures you can follow to shed those extra pounds you gained. Take a look!

What Causes Weight Gain After Surgery?

Do not panic if your weight increases after surgery. You just need to figure out the exact reason and work on it.

1. Water Retention

Water retention is medically known as postoperative edema. It is one of the major causes of weight gain after surgery (2).

Edema is the fluid accumulation between the tissues caused by the redistribution of plasma proteins. Post-surgery tissue injury results in massive shifts of fluids in between body compartments, leading to the accumulation of fluid in the interstitial space, i.e., the space between the organs in your body (3).

This fluid retention can be localized in the extremities, or it can be generalized, giving you an overall plumper appearance.

2. Stress

Woman crying and covering her face due to stress and a headache.

Image: Shutterstock

Both physical and psychological stress can trigger hormonal imbalance, which can cause weight gain. Stress for prolonged periods burdens the adrenal glands and causes them to secrete more of the cortisol hormonei  XAlso called the stress hormone, it controls your mood, sleep cycle, blood sugar and the body's use of carbohydrates, fats, and proteins. (4).

A study conducted on people who underwent cardiac surgery found that surgery-related stress increases both cortisol and antidiuretic hormonei  XA hormone that assists in blood vessel constriction and regulates both blood pressure and urine production. (ADH) secretion (5). Increased ADH levels may disturb the kidney functioning and cause water retention.

3. Trauma

Surgical trauma often leads to metabolic, immunological, and endocrine changes (6).

Trauma is a bodily response to distressing or disturbing events. Post-surgery trauma often disturbs the body’s equilibrium and creates a hormonal imbalance. This leads to the malfunctioning of the hypothalamic-pituitary-adrenal axisi  XA neuroendocrine system that manages the body’s response to stress and affects functions like digestion, and energy storage. , which further stresses the body (7).

A long-term observational study found that women with PTSD (post-traumatic stress disorder) tend to gain more weight and are at a higher risk of becoming overweight or obese (8).

4. Medication

Close up of a female doctor's hands holding pack of different tablet blisters at workplace.

Image: Shutterstock

Doctors often prescribe medication for post-surgery recovery. Most of these drugs are supplements to help regain your strength and promote faster healing. They may also prescribe certain medicines that affect your metabolic system and lead to weight gain (9).

5. Rest

Post-surgery recovery demands ample rest. Low activity and complete rest can slow down the body’s basal metabolic rate (BMR), which may result in weight gain.

Energy expenditure is directly related to your BMR and activity level. Low physical activity after a surgery can lower the BMR and calorie expenditure, which leads to weight gain (10). Doctors always suggest starting with slow physical activity after the recovery phase to revamp your body’s metabolic system.

6. Comfort Food

A young woman is in bed as her spouse brings scrumptious comfort food.

Image: Shutterstock

Who doesn’t want to indulge in comfort food? Besides, your loved ones may want to pamper you with all your favorite foods after your surgery. However, these comfort foods may make you gain weight.

Post-surgery blues often increase overindulgence in comfort foods, particularly high-sugar and high-fat foods. This, coupled with your already slow metabolism, can make you feel bloated.

Mary adds, “It is also possible for the body to bloat after surgery due to swelling and fluid retention.”

Now that you have zeroed in on the cause of your post-surgery weight gain, let’s check out some precautions that you can take to minimize it.

Precautions To Take To Minimize Post-Surgery Weight Gain

We know that we tend to gain weight after surgery (especially in the recovery stage). While gaining 5 to 6 pounds is normal, anything beyond that could lead to long-term issues. The following precautions can prevent this from happening:

  • Start to move around a bit. You don’t need to rush to the gym immediately after your surgery. Just keep yourself active by moving around as it helps revamp your metabolic system.
  • Practice some stretching exercises for better blood circulation. You can rotate your ankles or feet in clockwise and anticlockwise directions to prevent edema in the lower extremities.
  • You can pamper yourself with your favorite food once a week, but do not overindulge in it.
  • Include herbs like horsetail, parsley, cumin, and hibiscus in your food. They are natural diuretics that can help reduce water retention (11), (12), (13).

In addition to these precautions, you can also make certain dietary changes that can help prevent weight gain due to surgery.

Stylecraze Says
You can gradually start aerobic exercises, home exercises, or resistance exercises to lose weight after surgery (after consulting a physician) (17).

Dietary Changes To Lose Weight After Surgery

1. Focus On Lean Protein

Protein plays a key role in the recovery process. It helps repair and heal tissue damage, boosts immunity, and maintains a good metabolic rate (14).

Always focus on including good-quality protein in each meal. To avoid gaining weight, consume lean protein with low-fat content.

Include skinless white meat, lean cuts of beef or pork, eggs, fish, plant proteins like pulses, beans, legumes, and low-fat dairy products in your diet.

Try healthy cooking methods like steaming and add protein to your salads.

2. Eat More Vegetables And Fruits

A happy woman enjoying a variety of fresh fruits and veggies.

Image: Shutterstock

Vegetables and fruits are loaded with water and fiber that can help prevent excessive weight gain. Women often complain of developing belly fat after undergoing C-section. This was proven by a study conducted on mice (15). Hence, consuming more soluble fiber can help in this regard.

Moreover, vegetables and fruits are natural diuretics that can help drain out excess water from the body. Include cucumber, watermelon, lemon, asparagus, dandelion leaves, and nettle leaves in your diet. Spinach, broccoli, cabbage, cauliflower, tomatoes, pepper, mushrooms, aubergines, and other green leafy vegetables are also great choices.

However, we suggest you speak to your doctor/nutritionist before making these changes to your diet. Make sure to inform them about any medication you are taking.

Stylecraze Says
You can also make smoothies or juices out of the vegetables and fruits. Their soluble fiber can help you lose the post-surgery weight while keeping you hydrated.

3. Keep Yourself Hydrated

Young Asian woman drinking water while sitting on sofa at home.

Image: Shutterstock

A study conducted on girls who were overweight found that drinking plenty of water improves your metabolic rate and digestion (16).

Adequate water intake prevents excess fluid retention by sending a signal to the kidneys to stop conserving water. But if you have any serious kidney issues, please consult your doctor before increasing your water intake.

Infographic: Reasons Behind Post-Surgery Weight Gain

Post-surgery aftercare is just as important as the actual procedure itself. You must adhere to a prescribed medicine schedule and take adequate rest. That said, you also may notice unexpected weight fluctuations during this phase. What could the causes be? Check out the infographic below to learn more about the same.

reasons behind post surgery weight gain (infographic)

Illustration: StyleCraze Design Team

Save the high-quality PDF version on your device now.

Download Infographic in PDF version Download Infographic
Download Infographic in PDF version

Do not worry about weight gain after surgery. It happens as a result of medications prescribed for faster recovery, water retention, stress, or overindulgence in food post-surgery to keep the blues at bay. Following a few preventative measures can keep you from putting on those extra pounds. Remember, it is normal to gain a few pounds during post-surgery rehabilitation. All you need to do is follow a healthy and balanced diet, reduce your stress levels, and drink plenty of water. Consult your healthcare provider in case this unwanted weight persists even after following these tips.

Frequently Asked Questions

Does postoperative swelling cause weight gain?

Postoperative swelling is caused by water retention, which can lead to weight gain in the recovery phase. Eating balanced meals and a bit of exercise can help you overcome post-surgery weight gain.

Does general anesthesia make you gain weight?

Anesthesia usually does not make you gain weight. But intravenous (IV) fluids, when taken for a long period, can lead to weight gain after a surgery.Mary adds, “Anesthesia can increase appetite in some people, making them feel hungrier than usual, while other people may experience a decrease in appetite.”

How much water do you retain after surgery?

Water retention depends on the type of surgery you undergo. A minor surgery may only lead to minimal fluid retention, but a kidney transplant or a heart surgery can lead to more water retention.

Is fluid retention normal after surgery?

Yes, fluid retention is normal after surgery. Do not worry about it. Take proper rest to overcome the situation.

Can surgery affect your metabolism?

Yes, surgery affects metabolism as surgical stress increases protein breakdown. It may decrease metabolic rate and slow down the rate at which calories are burned.

Does walking reduce swelling after surgery?

Yes, walking after surgery lowers the risk of complications, increases circulation, alleviates swelling, and promotes faster healing.

How long does weight gain last after surgery?

You may start losing weight after a month of the surgery as the fluid retention subsides. You may notice weight loss during the initial 3 months of healing. However, it also depends on the type of surgery and other factors (medications, lifestyle, etc.)


Articles on StyleCraze are backed by verified information from peer-reviewed and academic research papers, reputed organizations, research institutions, and medical associations to ensure accuracy and relevance. Check out our editorial policy for further details.
  • Shulman, Holly B et al. “The Pregnancy Risk Assessment Monitoring System (PRAMS): Overview of Design and Methodology.” American journal of public health vol. 108,10 (2018): 1305-1313. doi:10.2105/AJPH.2018.304563
  • Itobi, E et al. “Impact of oedema on recovery after major abdominal surgery and potential value of multifrequency bioimpedance measurements.” The British journal of surgery vol. 93,3 (2006): 354-61. doi:10.1002/bjs.5259
  • Vaughan-Shaw, P G et al. “Oedema is associated with clinical outcome following emergency abdominal surgery.” Annals of the Royal College of Surgeons of England vol. 95,6 (2013): 390-6. doi:10.1308/003588413X13629960046552
  • Block, Jason P et al. “Psychosocial stress and change in weight among US adults.” American journal of epidemiology vol. 170,2 (2009): 181-92. doi:10.1093/aje/kwp104
  • Oka, Y et al. “Cortisol and antidiuretic hormone responses to stress in cardiac surgical patients.” Canadian Anaesthetists’ Society journal vol. 28,4 (1981): 334-8. doi:10.1007/bf03007799
  • Şimşek, Turgay et al. “Response to trauma and metabolic changes: posttraumatic metabolism.” Ulusal cerrahi dergisi vol. 30,3 153-9. 1 Sep. 2014, doi:10.5152/UCD.2014.2653
  • Finnerty, Celeste C et al. “The surgically induced stress response.” JPEN. Journal of parenteral and enteral nutrition vol. 37,5 Suppl (2013): 21S-9S. doi:10.1177/0148607113496117
  • Kubzansky, Laura D., et al. “The weight of traumatic stress: a prospective study of posttraumatic stress disorder symptoms and weight status in women.” JAMA psychiatry 71.1 (2014): 44-51.
  • Wharton, Sean et al. “Medications that cause weight gain and alternatives in Canada: a narrative review.” Diabetes, metabolic syndrome and obesity : targets and therapy vol. 11 427-438. 21 Aug. 2018, doi:10.2147/DMSO.S171365
  • Ravussin, E et al. “Reduced rate of energy expenditure as a risk factor for body-weight gain.” The New England journal of medicine vol. 318,8 (1988): 467-72. doi:10.1056/NEJM198802253180802
  • Carneiro, Danilo Maciel et al. “Randomized, Double-Blind Clinical Trial to Assess the Acute Diuretic Effect of Equisetum arvense (Field Horsetail) in Healthy Volunteers.” Evidence-based complementary and alternative medicine : eCAM vol. 2014 (2014): 760683. doi:10.1155/2014/760683
  • Kreydiyyeh, Sawsan Ibrahim, and Julnar Usta. “Diuretic effect and mechanism of action of parsley.” Journal of ethnopharmacology vol. 79,3 (2002): 353-7. doi:10.1016/s0378-8741(01)00408-1
  • Jiménez-Ferrer, Enrique et al. “Diuretic effect of compounds from Hibiscus sabdariffa by modulation of the aldosterone activity.” Planta medica vol. 78,18 (2012): 1893-8. doi:10.1055/s-0032-1327864
  • Institute of Medicine (US) Committee on Military Nutrition Research. “The Role of Protein and Amino Acids in Sustaining and Enhancing Performance.” Committee on Military Nutrition Research: Activity Report: December 1, 1994 through May 31, 1999., U.S. National Library of Medicine, 1 Jan. 1999.
  • Martinez, Keith A 2nd et al. “Increased weight gain by C-section: Functional significance of the primordial microbiome.” Science advances vol. 3,10 eaao1874. 11 Oct. 2017, doi:10.1126/sciadv.aao1874
  • Vij, Vinu A, and Anjali S Joshi. “Effect of ‘water induced thermogenesis’ on body weight, body mass index and body composition of overweight subjects.” Journal of clinical and diagnostic research : JCDR vol. 7,9 (2013): 1894-6. doi:10.7860/JCDR/2013/5862.3344.

Was this article helpful?
The following two tabs change content below.