Gluten-free diets for weight loss have been a trend that has stuck for many years. The theory is that steering clear of wheat, rye, and barley, which contain the protein gluten, helps people feel and look better. Recently, this kind of elimination diet has expanded to reducing lectins—other proteins found in in foods like grains, beans, and certain vegetables—that some blame for a host of health issues ranging from digestive distress to weight gain.

Do Gluten-Free Diets Work?

“Unless you have celiac disease or a true gluten sensitivity, there's no reason to exclude it from your diet,” says Ellen Klosz, a nutritionist at Consumer Reports. People may initially lose weight when they go gluten- or lectin-free, but that’s only because they’ve eliminated a huge source of calories in the form of foods like bread, pasta, and muffins. What’s more, there are now so many gluten-free, high-calorie processed food options available that you could easily put on pounds even though you’re not eating any gluten. And it’s possible to take in plenty of calories without ingesting a significant amount of lectins, too.

The Upside

If you’ve been diagnosed with celiac disease or gluten sensitivity, a gluten-free diet is a necessary treatment, but not for weight loss. In fact, people with these conditions often gain weight when they adopt a gluten-free diet. The damage gluten does to their intestines can prevent them from digesting food properly. Once that is corrected, more calories may be absorbed.

If you suspect that you’re sensitive to lectins, gluten, or any other food compound, see a specialist to get a diagnosis. A short-term elimination diet may help you pinpoint what’s giving you trouble; a registered dietitian can walk you through how to do one safely.

The Downside

Going gluten free can have unintended consequences. “Even if you take a supplement, you could still miss nutrients that you need,” says Klosz. People who ate less gluten were at a greater risk for developing type 2 diabetes, according to a study presented at an American Heart Association meeting in 2017. Research shows that going on a gluten-free diet may also decrease the number of healthy bacteria in the gut, which scientists say might make a person more susceptible to infections and the overgrowth of harmful bacteria.

And fruit, vegetable, legume, and whole grain consumption is consistently linked with decreased inflammation and risk of chronic diseases—a good reason to not eliminate lectin-containing foods like beans, tomatoes, potatoes, and quinoa. 

The Middle Ground

If your diet is heavy on carbs, dialing back your servings of bread, pasta, and more (gluten-free or not) can help you cut calories. And soaking, sprouting, cooking, and fermenting will break down lectins and help make foods easier for the body to process, in the event that they’re giving you a digestive problem.