Many people with a stoma can and do gain weight, sometimes more easily than they expect. In a study of nearly 150 ostomates, roughly two-thirds were classified as either overweight or obese, and only about a fifth were underweight. The reality is more nuanced than a simple yes or no, though, because stoma type, the length of remaining bowel, activity levels, and dietary habits all push the scale in different directions.
How Common Weight Gain Is After Stoma Surgery
A common misconception is that having a stoma means you will struggle to maintain or gain weight. For some people that is true, but the numbers tell a different story for the majority. In a cross-sectional study of 148 ostomized patients, about 45% were overweight and roughly 19% were obese, with colostomy patients especially likely to carry excess weight.1Journal of Coloproctology. Obesity and Physical Activity in Ostomized Patients A separate study looking at elderly stoma survivors found that about 35% had increased their BMI since surgery, while 44% stayed stable and only 20% lost weight.2PubMed Central. Changes in Body Mass Index and Stoma Related Problems in the Elderly So weight gain after stoma creation is not unusual at all. If anything, the surprise for many ostomates is that the weight creeps on rather than falls off.
Why the Type of Stoma Matters
Not all stomas are created equal when it comes to nutrient absorption, and the type you have plays the biggest role in determining whether weight gain comes easily or becomes a real challenge. A colostomy diverts the large intestine, but by the time digestive contents reach the colon, your small intestine has already absorbed the vast majority of calories, proteins, and fats. That means a colostomy barely changes how many calories your body takes in. Most colostomy patients absorb food almost as efficiently as they did before surgery, and their risk profile for weight gain looks a lot like anyone else’s.
An ileostomy, which diverts the end of the small intestine, introduces more variability. If you still have a reasonable length of small bowel and the ileostomy sits near the end of the ileum, you can still absorb most of your nutrients. Output tends to be more liquid and frequent than with a colostomy, and you lose more water and electrolytes, but caloric absorption often remains adequate. The risk of malnutrition and vitamin deficiency does go up, particularly for B vitamins.3PubMed Central. Nutritional Issues Faced by Patients with Intestinal Stoma: A Narrative Review Still, many ileostomy patients maintain or gain weight over time, especially once the gut has had a chance to adjust.
A jejunostomy, where the stoma opens from the upper small intestine, is the most challenging scenario. Much less bowel is available for absorption, which makes caloric intake far less efficient. People with a jejunostomy without colon in continuity face the steepest nutritional hurdles, partly because they cannot benefit from the colon’s ability to salvage energy through bacterial fermentation of carbohydrates into short-chain fatty acids.4PubMed Central. Management of patients with a short bowel For these patients, gaining weight without nutritional support is genuinely difficult.
The Short Bowel and High-Output Exceptions
The group most likely to struggle with weight gain is people with short bowel syndrome, a condition that develops when so much small intestine has been removed that the remaining gut cannot absorb enough nutrients and fluid on its own. Patients with less than about 100 cm of residual jejunum and no colon in continuity are sometimes classified as net “secretors,” meaning their stoma actually puts out more fluid than they take in by mouth.5PubMed. Successful weaning from parenteral nutrition in a short bowel syndrome patient with high-output stoma through restricted oral diet: a case report Gaining weight under those conditions typically requires parenteral nutrition (intravenous feeding), careful fluid management, and close medical supervision.
Even without a formal short bowel syndrome diagnosis, a high-output stoma can create its own problems. When the stoma puts out large volumes of fluid, sodium-rich secretions are lost, triggering intense thirst. The natural response is to drink lots of water or other low-sodium fluids, but this actually pulls more sodium from the blood into the gut, increasing stoma output further and creating a vicious cycle of dehydration and electrolyte loss.6PubMed Central. Strategies for Managing Fluids and Electrolytes in High-Output Stomas: A Systematic Review and Evidence Summary Until that cycle is broken, weight gain is unlikely. The focus shifts to staying hydrated and keeping electrolytes in balance rather than worrying about calories.7PubMed Central. How to manage a high-output stoma
These situations, though, represent the minority of ostomates. They are real and serious, but they should not be treated as the default experience. For the majority of people living with a colostomy or a well-functioning ileostomy, the digestive system absorbs enough calories to support weight maintenance and, for many, weight gain.
How the Gut Adapts Over Time
One reason weight gain becomes easier as months pass after surgery is a process called intestinal adaptation. When a section of bowel is removed, the remaining intestine gradually compensates by increasing its absorptive surface area. The villi (tiny finger-like projections lining the intestine) grow longer, and the crypts at their base deepen, effectively packing more absorptive tissue into each centimeter of gut.8PubMed Central. The Pathogenesis of Resection-Associated Intestinal Adaptation
Animal studies have measured how dramatic this remodeling can be. After colectomy and reconstruction, the mucosal absorptive surface in the jejunum increased by about 59%, and in the ileum by about 76%, with corresponding increases in glucose and electrolyte absorption.9PubMed. Morphological and functional adaptation of the small intestine after colectomy and ileal pouch-anal anastomosis in rats Human adaptation follows a similar trajectory, though the timeline varies. This means that someone who initially struggles to absorb enough calories in the early months after stoma creation may gradually become more efficient at it, making weight gain increasingly possible over time.
Why So Many Ostomates Gain More Than They Expect
If malabsorption were the whole story, you would expect most ostomates to be thin. But as the obesity prevalence data show, the opposite is often true. Several factors conspire to push weight upward.
Reduced physical activity is one of the biggest drivers. Fear of developing a parastomal hernia, which is a bulge of tissue through the abdominal wall around the stoma, keeps many people from exercising. In one survey, nearly a third of ostomates with a medically diagnosed hernia reported being “much less active” than they were before surgery, compared with about a fifth of those without a hernia.10PubMed. Parastomal hernia and physical activity. Are patients getting the right advice? Even among those who have not developed a hernia, many pull back from exercise because they are unsure what is safe. The fear of hernia is frequently cited as a major barrier to activity.11PubMed. Physical activity and exercise after stoma surgery: overcoming the barriers Less movement with unchanged or increased calorie intake is a straightforward path to weight gain.
Dietary shifts matter as well. After stoma surgery, many people are cautious about what they eat, sometimes avoiding high-fiber foods or anything that might cause blockages or excessive gas. That caution can inadvertently steer them toward softer, more processed, calorie-dense foods. Others find that certain comfort foods feel “safe” and settle on a narrower diet that happens to be higher in refined carbohydrates and fats. The emotional dimension of living with a stoma also plays in: stress, anxiety about leaks, and changes in body image can all influence eating habits in ways that favor weight gain.
Age is another contributor. Many stoma surgeries are performed in people over 60, often for colorectal cancer, and this population already faces metabolic slowdown and muscle loss that make weight management harder regardless of the stoma.
What Happens to Your Body When Weight Increases After Stoma Surgery
Gaining weight with a stoma is not just a cosmetic or general-health concern. It creates specific practical problems that affect daily stoma care and long-term surgical outcomes.
The most studied complication is parastomal hernia. A BMI above 25 is an independent risk factor for developing one. A review of the literature identified elevated BMI as one of the top ten risk factors, alongside age, gender, and diabetes.12PubMed Central. Risk Factors for the Development of Parastomal Hernia: A Narrative Review One study found that BMI over 25 carried about 1.8 times the hazard of parastomal hernia in a multivariate analysis.13Annals of Coloproctology. Incidence and Risk Factors of Parastomal Hernia Body composition matters too: a Japanese study found that a high subcutaneous fat area was a strong independent predictor of parastomal hernia, even after accounting for BMI itself.14Journal of the Anus, Rectum and Colon. High Subcutaneous Fat Area Is an Independent Risk Factor for Parastomal Hernia after Transperitoneal Colostomy for Colorectal Cancer So it is not just overall weight but where the fat accumulates, particularly around the abdomen, that matters.
Day-to-day stoma management also gets harder. Survivors whose BMI increased after surgery were roughly twice as likely to report stoma-related problems and about 50% more likely to say the stoma interfered with their clothing compared to those whose weight stayed stable. Those who were obese at the time they were surveyed had similar issues: nearly twice the rate of clothing interference and about 70% higher odds of “other” stoma-related problems.2PubMed Central. Changes in Body Mass Index and Stoma Related Problems in the Elderly Weight gain changes the contour of the abdomen around the stoma, which can make appliance adhesion unreliable, increase leaks, and cause skin irritation. If you have been managing your stoma comfortably and then gain a significant amount of weight, expect that your appliance fit may need to be re-evaluated.
Higher BMI and Stoma Reversal Complications
For people whose stoma is temporary, there is an additional reason to pay attention to weight: it affects outcomes if and when the stoma is reversed. A systematic review and meta-analysis found that a BMI over 30 was associated with roughly double the overall complication risk after ileostomy reversal. Overweight patients (BMI over 25) did not show a significant increase in most complications, but they did have dramatically higher odds of developing a stoma-site incisional hernia after reversal, with the risk increasing more than fourfold.15PubMed Central. Higher BMI increases risk of stoma-site incisional hernia and other complications following diverting loop ileostomy and reversal: a systematic review and meta-analysis Every study included in the review identified elevated BMI as a risk factor for hernia at the reversal site. If you are living with a temporary stoma and planning for reversal, keeping your weight in a reasonable range is one of the modifiable factors that can improve your surgical outcome.
Metabolic and Microbiome Shifts After Stoma Creation
Beyond the straightforward calories-in, calories-out framework, having a stoma changes your internal biology in subtler ways. The gut microbiome, the community of bacteria living in your intestines, is significantly altered. In patients with an ileostomy, the effluent and the disconnected colon both show reduced bacterial diversity, with a shift toward aerobic and potentially harmful species. Researchers have found that this altered microbial state may contribute to metabolic imbalance.16PubMed Central. Gut microbiome and plasma metabolome alterations in ileostomy and after closure of ileostomy In infants with small bowel stomas, those who were growing poorly showed a dominance of certain bacterial groups compared to infants growing well, alongside changes in bile acid metabolism that correlated with worse nutritional outcomes.17PubMed. Intestinal microbial and metabolite profile in infants with small bowel stomas after bowel resection
How these microbiome changes affect weight in adults over the long term is not yet clear. In the general population, certain microbial profiles are associated with obesity, and others with leanness. Whether the stoma-related shift pushes metabolism in one direction or another is still an open research question. What is clear is that the gut environment changes, and those changes interact with nutrition, inflammation, and metabolic health in ways science is still working out.
Resting energy expenditure, essentially how many calories your body burns while doing nothing, does not appear to change dramatically after major abdominal surgery. One study measuring metabolic rate before and after surgery found no significant shift in resting energy expenditure overall, though the body did switch to burning more fat and less carbohydrate in the postoperative period.18Journal of Parenteral and Enteral Nutrition. Preoperative and Postoperative Resting Energy Expenditure of Patients Undergoing Major Abdominal Operations This means the surgery itself does not meaningfully slow your metabolism. If you are gaining weight, it is far more likely related to what and how much you are eating and how active you are, not to some metabolic reset from the operation.
Getting the Right Nutritional Guidance
One of the more consistent findings across the research is that ostomates often feel underprepared for managing their diet after discharge from the hospital. Qualitative research with stoma patients has found that a follow-up session with a dietitian could help people develop strategies for managing weight changes, preventing dehydration, and lowering the risk of malnutrition.19Nutrition in Clinical Practice. Exploring the experiences of patients who receive nutrition education for ostomy care: A qualitative research design In practice, many patients do not receive this follow-up. They are sent home with general advice about avoiding blockages and staying hydrated, but not with a personalized plan for managing caloric intake or navigating the dietary changes that come with a stoma.
If you have a colostomy and are concerned about weight gain, the approach is essentially the same as for anyone else: balanced eating, portion awareness, and regular physical activity. If you have an ileostomy, you need to factor in the increased fluid and electrolyte losses, which means paying closer attention to hydration, salt intake, and any foods that dramatically increase output. If you have a high-output stoma or short bowel syndrome, weight management is a medical issue that belongs in the hands of a gastroenterologist and dietitian, not something to figure out alone.
Exercise With a Stoma
The fear of parastomal hernia is understandable given how common hernias are in ostomates, but the irony is that avoiding exercise may increase weight, which itself raises hernia risk. Most stoma nurses and colorectal surgeons encourage a gradual return to physical activity after the initial healing period. Walking, swimming, cycling, and light resistance training are all generally considered safe. Heavy lifting and high-impact abdominal exercises deserve more caution, particularly in the early months, but a blanket avoidance of all physical activity does more harm than good.
The research showing that ostomates with hernias become significantly less active highlights a feedback loop: hernia leads to inactivity, inactivity leads to weight gain, and weight gain increases the risk of the hernia worsening or recurring.10PubMed. Parastomal hernia and physical activity. Are patients getting the right advice? The increased inactivity also raises the risk of other chronic conditions, including cardiovascular disease and diabetes. Getting clear, individualized guidance from a stoma care nurse about what activities are appropriate is one of the most useful things you can do, both for weight management and for overall health. The evidence suggests many ostomates are not getting that advice, or are receiving overly cautious recommendations that leave them unsure and sedentary.11PubMed. Physical activity and exercise after stoma surgery: overcoming the barriers
Support belts designed for ostomates can provide abdominal support during activity and may reduce anxiety about hernia. They are not a guarantee against hernia development, but many people find them reassuring enough to get moving again. If parastomal hernia has already developed, a surgical consult can determine whether repair is appropriate and what level of activity is realistic in the meantime.