It can take a couple days to start to feel less bloating, but the true test is to keep up for two to three months to make sure.

Several weeks should do it if you truly have celiac disease.

A few days.

Celiac disease, also known as Gluten Sensitive Enteropathy, is an auto-immune disorder that results in the "blunting" of the microvilli in the small intestine, which can lead to malabsorption and a wide variety of symptoms. By avoiding "gliadin," the microvilli literally grow back. This process, depending on the severity of loss (histologically graded as a Marsh score), takes weeks to return to normal.

The superficial layer of the intestine is replaced about every week. However inflammation due to dietary elements, such as gluten (among others), occurs in a deeper layer, resolving at a slower rate. Ordinarily, removal of inflammatory diet results in maximum gastrointestinal symptom improvement fairly quickly, within 4 to 8 weeks in the majority of affected people. It is important to remember that this is gradual, meaning that many experience progressive improvement as time goes by. This means that people can experience improvements in shorter periods of time but that maximum improvement takes a longer. In people with non-intestinal manifestations of intestinal inflammation (joint pain, dermatitis, “brain fog“, et c.) symptom improvement can take even longer, but these also can gradually improve as time passes.

It often depends on the person but most people need a minimum of 3 months until they will start to notice a difference. For some it is longer than this.

Tricky question because many celiac patients have no GI symptoms, and any GI symptoms present may not be secondary to celiac. However, in general, if celiac is causing symptoms, improvement should be noted within a few days of strict GFD. Long-term improvement or resolution takes longer, 4-6 weeks, allowing time for the duodenal mucosa to normalize.

1 month

At least 6 to 8 weeks to really understand a change.

In our experience, many feel an improvement in abdominal symptoms/bowel habits within 3-4 weeks. Many feel dramatically better after 3-4 months. Some of the anatomic/architectural changes in the small bowel may take a bit longer. It's key to review dietary ingestions for any "hidden" forms of gluten. Thoughtful review with a nutrionist can be very helpful.