Over the past few years, there’s been a rise in the amount of celebrities and health bloggers promoting the use of a gluten-free diet for weight loss purposes. Claimants say it improves digestion and boosts energy levels, but does the science back these raving testimonials?
Gluten is a protein found mostly in grains like wheat and barley. It is known to inflame and damage the intestines of people with celiac disease. For those with non-celiac gluten sensitivity, it can cause symptoms like bloating, gas and diarrhea. A gluten-free diet is the sole treatment for these conditions. But for the vast majority of the population, gluten poses no risk and does not need to be avoided.
Yet as researchers from The Journal of Pediatrics point out, almost a third of Americans are now cutting down on their gluten consumption, despite celiac rates remaining stable over time. However, there is no evidence that gluten-free diets can provide any substantial health benefits to those who have no problems digesting gluten. Despite many health claims, gluten-free diets have not been shown to reduce the risk of heart disease or type 2 diabetes.
So is a gluten-free diet for weight loss fact or fiction? Read on as we unpack the science.
How does a gluten-free diet work?
A gluten-free diet eliminates all foods containing or contaminated with gluten. According to the Celiac Disease Foundation, the main sources of gluten include grains like wheat, rye, barley, triticale and cross-contaminated oats, as well as their derivatives – malt, brewer’s yeast and wheat starch. Therefore individuals who suffer from celiac disease or gluten sensitivity need to avoid many common food staples, including pasta, noodles, bread, baked goods, breakfast cereals and beer.
Gluten is also commonly found in sauces and condiments, particularly soy sauce and malt vinegar. What’s more, food manufacturers use it as a food additive or filler. In these cases, it’s usually listed on labels as maltodextrin or wheat starch.
Is there a connection between gluten and weight loss?
Since gluten-free alternatives tend to be expensive and hard to get hold of, a typical gluten-free diet usually consists of naturally gluten-free whole foods, including fruits, vegetables, and gluten-free grains like brown rice, quinoa, and millet. Removing foods that are high in simple carbohydrates and swapping them with minimally processed, fiber-rich foods may indeed help to promote weight loss and a feeling of wellbeing.
Anecdotal evidence from clinical practice suggests that celiac patients who switch to a gluten-free diet may find it easier to lose weight. “Generally, they lose inches at the waist and pounds,” agrees Dr Monika Wassermann, medical doctor at Oliolusso. However, there is no evidence that gluten itself contributes to weight gain or interferes with weight loss in any meaningful way.
“What typically happens if someone avoids gluten is that they limit carbohydrates and therefore end up losing weight. It is never the gluten, just the restrictive diet that induces weight loss,” says Sophie Medlin, Doctify-reviewed consultant dietitian and director of CityDietitians.
So what does science say about gluten-free diets for weight loss? Research studies show mixed results. Many papers have demonstrated that cutting out gluten can actually contribute to weight gain. According to a study published in the Alimentary Pharmacology and Therapeutics journal, a gluten-free diet caused 15.8% of Celiac patients to move from a normal or low BMI into an overweight BMI class, while 22% of already overweight patients gained more weight. A similar study from The American Journal of Gastroenterology has shown that 81% of Celiac patients gain weight after two years on a gluten-free diet.
At the same time, researchers from the European Journal of Internal Medicine and the Journal of Clinical Gastroenterology have found that cutting out gluten may have a beneficial effect on BMI, both for the underweight and the obese individuals alike. A 2013 animal study also found that a gluten-free diet can increase fat burning abilities, as well as reduce insulin resistance and inflammation within fat tissue. However, human studies are needed to confirm these findings.
What could be the reason behind these stark differences? Many scientists noted that at diagnosis, most celiac patients were overweight and did not have a good understanding of healthy nutrition.
Are gluten-free foods healthier for you?
Gluten adds texture, structure, aroma and mouthfeel to baked products. To mimic the functional and sensory effects of gluten, many gluten-free products may be enriched with less healthy ingredients.
“Food manufactures have to add more fat, sugar and additives to make the food taste nice and behave like it has gluten in it,” says Medlin. “Something being gluten free is not in any way associated with it being healthier.”
Williams adds: “A gluten-free cookie will still contain a high amount of sugar, fats and carbs, just as a regular cookie would. In this case, choosing the gluten-free option does not mean that it is healthier.”
Medical professionals are also concerned that gluten-free diets may lead to potential nutrient deficiencies. “My main concern is how one recovers the major complex carbohydrate sources eliminated from your meals,” says Dr Wassermann. “The diet also denies you B vitamins, fiber, folate, calcium, and iron found in carbohydrates,” she adds.
According to a review published in the Nutrients journal, cutting out gluten may lead to a significantly lower intake of protein, magnesium, potassium, vitamin E, folate, and sodium.
Should you avoid gluten even if you’re not celiac?
If you don’t suffer from celiac disease or gluten sensitivity, you should “absolutely not” cut out gluten from your diet, says Medlin. “It can be harmful to your gut health and it causes unnecessary dietary restriction. Anyone with celiac disease would wish they could just eat gluten again. Excluding it causes all kinds of problems.”
This article is for informational purposes only and is not meant to offer medical advice.
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Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master’s degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.