In August 2012, Lady Gaga told the Australian cable news channel Sky News that she was “on a mission to lose 10 pounds on a gluten-free diet,” according to The Huffington Post. The pop star was “hoping that eating wheat-free will give her the energy she needs to power through the remaining legs of her international tour.”
When people who have celiac disease eat gluten—a protein found in wheat, barley, and rye—it triggers an abnormal immune response that damages the lining of the small intestine. That can cause diarrhea, cramps, pain, bloating, and vitamin deficiencies. Avoiding gluten, even tiny amounts, can allow the damage to heal.
But does going gluten free make the pounds melt away?
“There’s no evidence from studies that that’s true,” says gluten expert Joseph Murray, a gastroenterologist at the Mayo Clinic in Rochester, Minnesota. “When patients with celiac disease go on a gluten-free diet, some go up in weight and some go down, but most don’t change.”
For people without celiac disease, it’s not avoiding gluten, but the foods gluten comes in, that may matter.
“Whenever anyone goes on any restrictive diet, they typically end up eating less, because food is not so readily available,” says Murray. “That’s one of the major reasons we eat too much. Food is too available. If you go gluten free, it’s not so easy to get fast food.”
It’s not just fast food that’s not available. Suddenly, breads, bagels, pasta, pizza, burritos, pancakes, muffins, doughnuts, cupcakes, cookies, pies, pretzels, and dozens of other foods get wiped off your plate. What’s left? For Lady Gaga, it was mostly fish, chicken, and vegetables.
“Is there something about wheat products or gluten-containing foods that causes weight gain beyond their calories?” asks Murray. “I don’t think so.”
Fatigue is a different story.
“For the great majority of patients with celiac disease, fatigue is a major symptom,” notes Murray. “It may be partly due to vitamin deficiencies or to inflammation in the intestine. And it usually gets better on a gluten-free diet, though it takes weeks or months for the recovery.”
But people without celiac may also report fatigue that diminishes on a gluten-free diet. Why?
“For one thing, you don’t eat that great big carbohydrate with your midday meal,” says Murray. “Certain foods that happen to be rich in gluten may produce sleepiness because of the carbohydrate load or calorie load.”
That raises a different question: Instead of seeing a doctor, should people with fatigue or stomach problems simply try a gluten-free diet to see if they feel better?
“That’s not a good idea,” says Murray. “First, if you do have celiac disease, it’s much more challenging to get diagnosed if you’re already on a gluten-free diet.”
When the doctor takes a biopsy of the lining of your small intestine, it won’t show damage if you’ve been off gluten.
And some people feel better on a gluten-free diet simply because they expect to. It’s a placebo effect.
“About a third of people will respond for two or three months, and then the placebo effect wears off,” says Murray. “They may feel better because they’re eating less food or less junk food. But the symptoms could start coming back and then you’re stuck in a diagnostic mystery.”
Meanwhile, other problems could get worse. Trying a gluten-free diet “could delay a diagnosis of Crohn’s disease,” notes Murray. “Or, God forbid, it could be cancer, and the diagnosis gets delayed while they’re on a gluten-free diet.”
What’s more, someone with celiac needs follow-up. “We need to make sure that the damage to the intestine heals, and that nutritional deficiencies are gone,” says Murray. “And family members need to be tested.”
And a gluten-free diet isn’t free. “There’s the excess cost, the diet can be low in vitamins and fiber, which can lead to constipation, and it’s a burden on family members.”
Ironically, people who are eating a gluten-free diet aren’t necessarily the ones who need to. Using blood samples from a nationally representative sample of roughly 7,800 people, Murray estimated the number of Americans with celiac.
“We estimate that 1.8 million Americans have celiac disease, but only 17 percent of them know it,” he says. Meanwhile, “1.6 million Americans are on a gluten-free diet, and the great majority of them do not have a diagnosis of celiac disease.
“The irony is that the people who have celiac disease and need to be on the gluten-free diet don’t know it, and we don’t know if many of the people who are on a gluten-free diet need to be on it.”
There’s one more complication: studies have found that some people without celiac get symptoms when they eat gluten.
“We don’t have a good test for patients with non-celiac gluten sensitivity,” says Murray. “If they’ve been tested for celiac and don’t have it but their symptoms are not explained by anything else, I’d say it’s worthwhile trying a gluten-free diet.”
“I wouldn’t do it for more than a month though,” he adds. “I see people who come to me after a year on a gluten-free diet. They’re totally convinced that they have gluten sensitivity, and I say, ‘But you’re no better than you were. Why don’t you just go back to eating gluten?’ And they say, ‘But it’s bad for me.’ And I ask, ‘How do you know that?’ We’re not always logical beings.”
Sources: Am. J. Clin. Nutr. 79: 669, 2004. Clin. Gastroenterol. Hepatol. 10: 893, 2012. Am. J. Gastroenterol. 107: 1538, 2012. Am. J. Gastroenterol. 106: 508, 516, 2011.