Your client cut out twelve foods and feels worse. They’re tired, they’re anxious about eating out, and they still don’t know which food, if any, was causing their symptoms. The elimination diet didn’t fail because the idea was wrong. It failed because of how it was done.
Used well, an elimination diet is a short, structured experiment: remove likely triggers, see whether symptoms change, then carefully add foods back to learn what the body tolerates. The goal, as AFPA’s Gut Health Nutrition Specialist curriculum frames it, is to expand the variety of foods a person can eat—not shrink it. Here’s where that process tends to go sideways.
Mistake 1: Using an Elimination Diet as a Diagnosis
An elimination diet can suggest a pattern. It can’t diagnose a food allergy, an intolerance, or a digestive disorder, and a coach making that call is outside their scope of practice. Holistic nutrition coaches can discuss the pros and cons of elimination approaches and help clients understand the foods on a protocol their provider has recommended. When symptoms are persistent or severe, the first step is a referral for appropriate medical evaluation and testing, recognizing that not all food sensitivity tests on the market are evidence-based.
Mistake 2: Cutting Too Much for Too Long
Most structured elimination protocols run about two to three weeks before reintroduction begins. Staying in the elimination phase indefinitely “just to be safe” is where over-restriction creeps in. Restriction has costs beyond inconvenience, too: Research summarized in AFPA’s Gut Health Specialist course shows that a gluten-free diet tends to reduce the abundance of beneficial gut bacteria in people who aren’t actually sensitive to gluten, and a low-FODMAP diet, useful for some people with IBS or SIBO, reduces total bacterial abundance and is generally meant to be used short-term.
Mistake 3: Rushing or Skipping Reintroduction
Reintroduction is where the learning actually happens, and it’s the phase clients most often skip or rush. A common structure is to add back one food at a time, roughly every two days, in a reasonably generous amount, while keeping a journal of everything eaten and every symptom noticed. Foods should be reintroduced individually and in their simplest form, such as milk or wheat. Reintroducing a mixed food like macaroni and cheese makes it difficult to identify which food is causing a reaction. If a result is unclear, the food is removed for about a week before trying again.
“In my experience, I see a lot of individuals cutting out foods for too long. Sometimes it’s because they don’t understand the ins and outs of how an elimination protocol is supposed to work. Other times, they might experience an outcome they’ve been pursuing, such as weight loss, and then feel they can’t ever add back in certain food groups. I remind clients that an elimination diet is a short-term experiment, not a long-term way of eating. That’s why we clearly define when the reintroduction phase begins, so that everyone is aware that the elimination portion of the diet has an end date. The more foods we can include in a client’s diet, the better. More variety supports a more diverse microbiome, more flexibility with meal planning, and less stress around eating occasions that might otherwise cause symptoms.” -Kellie Lunday, MS, RD, LD, NBC-HWC
Mistake 4: Turning It Into a Weight-Loss Diet
Elimination diets aren’t designed for weight loss and treating them that way muddies the results. Clients should eat a wide variety of the foods that remain, avoid restricting calories, keep regular meals and snacks to maintain steady energy, and aim for several servings of vegetables a day. If a client’s intake drops sharply during elimination, nutrient adequacy, not the scale, becomes the priority conversation, and it may be time to loop in their healthcare provider.
Mistake 5: Treating Food as the Only Variable
Digestive symptoms rarely have a single cause. The functional medicine “5R” framework taught in the Gut Health Specialist course (remove, replace, reinoculate, repair, and rebalance) ends with rebalancing stress, sleep, physical activity, and overall lifestyle for a reason. A client who removes six foods but is sleeping five hours a night under chronic stress may see little change and wrongly conclude the foods weren’t the issue or that more foods need to go.
The Coach’s Role: Structure, Support, and Knowing When to Refer
Nutrition coaches are well positioned to make elimination diets safer and more useful: Helping clients plan meals so the elimination phase is doable, keeping them from lingering in restriction, structuring a careful reintroduction, and watching for signs that restriction is affecting their relationship with food. Just as important is recognizing when a client needs a physician, registered dietitian, or mental health professional instead. Clients with a history of disordered eating, for example, need extra caution before any restrictive protocol.
Go deeper on gut health nutrition: AFPA Gut Health Nutrition Specialist Certificate
References:
- AFPA. (2023-a). Gut Health Nutrition Specialist Certificate, Module 5: The Impact of Nutrition on Gut Health.
- AFPA. (2023-b). Reference sheet of therapeutic diets and protocols and their research-based impact on gut and overall health. Gut Health Nutrition Specialist Certificate, Module 5.
- AFPA. (2025). Holistic Nutrition Coach Certification, Module 3: Nutrition as a Profession and Scope of Practice. Institute for Functional Medicine. (2016). Comprehensive elimination diet. Revised by Liz Lipski, PhD.
Ready to Specialize in Gut Health?
AFPA’s Gut Health Nutrition Specialist Certificate is an online, self-paced program with 8 modules, 5 case studies and 23 downloadable handouts. Finish in six months or less and gain the skills to support clients with digestive concerns.
