Gaining Weight When You Have Celiac Disease and Are Underweight

Evaluate your diet and bulk up your protein and fat intake

Woman weighing herself on scale

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Although most people who are diagnosed with celiac disease are a normal weight or overweight at the time they're diagnosed, around one in five are underweight. For them, gaining enough weight can sometimes be a challenge.

This may seem strange since the majority of people (including the majority of those with celiac disease) either weigh the right amount or weigh too much and want to lose weight, not gain weight. But being too skinny and unable to gain weight is a real problem for some. People who are underweight are at higher risk for malnutrition and osteoporosis, both of which already are issues for those with celiac disease.

So what can you do if you have celiac and are having trouble gaining weight? Courtney Schuchmann, M.S., R.D., L.D.N., a dietitian at the University of Chicago Medicine who works with people who have celiac disease, tells Verywell that there are multiple steps you can take to help gain weight, plus some additional medical concerns you may need to rule out.

Underweight and Celiac Disease

Celiac disease damages your small intestine, making you unable to absorb nutrients. This damage occurs when you ingest gluten, a protein found in the grains wheat, barley, and rye. Therefore, to halt the intestinal damage and begin to absorb nutrients again, people with celiac disease need to follow a strict gluten-free diet.

Still, although the stereotypical vision of a person with celiac disease pictures that person as rail-thin or emaciated due to celiac-related malnutrition, only around 17 percent to 20 percent of people who are diagnosed with celiac actually are underweight at the time of their diagnosis. Around 60 percent are a normal weight and the rest are overweight.

Women, people with more severe intestinal damage at diagnosis, and those who have diarrhea as a symptom are more likely to weigh too little at the time of their diagnosis, according to one study. That study, published in the Journal of Clinical Gastroenterology, reported that around two-thirds of those who started out underweight gained weight once they started the gluten-free diet.

That matches with what Schuchmann sees in practice. She says dietitians typically watch people with celiac disease who are underweight at diagnosis begin to put on weight as they start eating gluten-free and their intestinal villi begin to heal.

"These individuals begin to better absorb their nutrition and specifically calories," she says. In most cases, those with celiac who are underweight don't need to do anything special to gain weight—it happens naturally. But a few people need extra help, she says.

Gaining Weight When You're Too Thin

Typically, if a person with celiac disease doesn't gain weight after a few months of being on a strict gluten-free diet, Schuchmann says she considers "a more vigorous approach to weight gain."

The first step, she says, is to make sure that person really is eating gluten-free, since eating gluten-containing foods or even just eating food that's been cross-contaminated with gluten can keep the intestinal villi from healing, contributing to ongoing symptoms and malnutrition.

Once she's addressed gluten ingestion, Schuchmann recommends the following weight-gain strategies for those who are underweight:

  • Increasing caloric intake with nutrient-dense foods that are higher in fat, such as gluten-free flax seed, chia seed, avocado, cheese, nuts, and seeds. Since fat has more calories per gram than carbohydrates and protein, this can help increase the amount of calories you're eating without increasing the overall amount of food.
  • Increasing the amount of protein-rich foods you eat, such as Greek yogurt, eggs, lean meats, cheese, nuts, seeds, and protein shakes made with gluten-free protein powder. This can help you keep and build your lean muscle mass.
  • Consider adding nutritional shakes if you're really struggling. Gluten-free options include Ensure and Boost ready-to-drink products (avoid Boost High-Protein Powder Drink Mix, as that contains gluten).

People following this program can expect to gain about 1 to 2 pounds per week, or a minimum of 4 pounds in a month, Schuchmann says.

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Addressing Gluten Cross-Contamination

People with celiac disease who continue to ingest gluten (even in trace amounts) may delay or prevent the healing of their small intestine, and may prevent themselves from gaining weight. There are several ways you can put yourself at risk for this problem, Schuchmann says:

"Every individual with celiac disease has a different level of sensitivity to cross-contamination and the level or amount of gluten ingested, and the impact it will have on symptoms, gut healing, and weight management issues," Schuchmann says. "Anyone with difficulty gaining weight and persistent symptoms should re-evaluate their diet and lifestyle to minimize gluten ingestion as much as possible."

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A Word From Verywell

If you're having trouble gaining weight despite following the advice of your doctor and dietitian, there may be something else going on. Celiac disease is an autoimmune condition, and those with one autoimmune condition are at higher risk for developing related autoimmune conditions.

Specifically, celiac disease is linked with both thyroid disease and diabetes, both of which can contribute to problems gaining or losing weight. Therefore, you may need some additional testing if you just can't seem to gain weight.

Finally, a very small percentage of people with celiac disease who fail to gain weight despite a careful gluten-free diet actually may have refractory celiac disease, a condition in which your small intestine does not heal even though you're eating gluten-free. Refractory celiac disease also causes ongoing symptoms, such as diarrhea. Talk to your doctor if you're concerned about this—for most people who experience ongoing symptoms and problems with their weight, the cause is hidden gluten in their diets or another medical condition, not refractory celiac disease, which is extremely rare.

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Article Sources
  • Cheng J et al. Body Mass Index in Celiac Disease: Beneficial Effect of a Gluten-Free Diet. Journal of Clinical Gastroenterology. 2010 Apr;44(4):267-71. DOI: 10.1097/MCG.0b013e3181b7ed58.