The SIBO Specific Food Guide Diet (SSFG): Our Verdict

What is the SIBO SFG Diet?

The diet includes restrictions based on Siebecker’s clinical experience with treating SIBO. Like other SIBO diets, the goal of the SSFG is to decrease the amount of fermentable carbohydrates to ‘starve’ gut bacteria contributing to SIBO.

In the SSFG, Siebecker breaks foods into 4 color-coded categories used to describe the degree of fermentability. An example can be seen below. The full SSFG can be accessed here. 

Next to the elemental diet, the SSFG is the most restrictive of the therapeutic diets for SIBO. Siebecker gives few guidelines for the SSFG. Currently, there is no evidence on the SSFG, specifically. Research exists for both the Low FODMAP diet and the SCD; however, neither diet has research to support the treatment or management of SIBO. 

How to do the diet

SSFG Step 1: Starting the diet

To start the SSFG, Siebecker recommends following the intro diet from either the SCD, GAPS or SCD Lifestyle plans using only low and moderate FODMAP-containing foods. 

Given that the diet combines components of the SCD and the low FODMAP diet, we used the SCD intro diet to compile a list of appropriate foods for this introductory phase.

We excluded the few high FODMAP foods typically allowed in the introductory diet according to Siebecker’s recommendations.  

Sample SSFG Intro Diet: Appropriate Foods

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Intro Diet Duration (1-5 days)

The SCD suggests the intro diet be followed for up to five days when symptoms such as diarrhea or cramping are severe. In other cases, one or two days on the intro diet is said to be sufficient. S We would assume that Siebecker intends for the intro diet to be followed for the same duration as suggested in the SCD diet. 

Step 2: After the Introduction Diet -- The Intermediate Phase

Siebecker makes the following suggestions for this intermediate phase of the diet: 

• Wait 1-3 months to introduce 
• Celery root
• Rutabagas
• Cruciferous vegetables
• Beans
• Seeds
• Nuts 
• Including nut flours, butters, & milks 
• Coffee
• Alcohol
• Raw vegetables/salads
• Raw fruit. 
• Cook, peel, de-seed, and puree vegetables and fruits at first. 
• Avoid dairy for the first few weeks if unsure of its tolerability

• SCD-approved moderate FODMAP content foods are to be limited to one serving per meal. 
• Meals are to be separated by 3-4 hours. 
• Though not explicitly stated, we assume that remaining low FODMAP and SCD-approved foods can be eaten in their cooked, peeled, and de-seeded forms during the intermediate phase. 
• We also assume high fodmap foods are to be avoided 
• Few details are given as to when it’s best to liberalize the diet to include several restricted foods in this phase. We assume this is based on tolerance, but again, no guidance is offered. 

Step 3: The Final Phase

Once the poorly defined 1-3 month intermediate phase of the diet ends, we assume foods that are acceptable on both the low FODMAP diet and the SCD could be eaten in their raw and/or cooked forms. 

We also assume that the 1 moderate FODMAP food per meal rule still applies in this phase. These are all assumptions, as none of this is explicitly stated. Moreover, the steps we have outlined here were not explicitly stated but generated based on our perception that the diet is carried out through a 3-phased approach. 

No details are given as to how long someone should stay on the diet. Siebecker recommends tailoring the diet and trusting your body's reactions to foods over trusting the list. She also suggests periodically re-testing foods to assess for improved tolerance. No guidelines or parameters are given on when and how to reintroduce foods. 

What’s new with this approach?

As Siebecker suggests, the SSFG further restricts fermentable carbohydrates compared to the low FODMAP diet and the SCD. The diet removes SCD approved foods that may be gas-forming or have an osmotic effect (e.g., fructans and polyols). The diet also restricts certain fermentable starches in the diet that are otherwise allowed on a low FODMAP diet. 

It’s reasonable to believe the diet would provide fewer compounds for intestinal bacteria to ferment. The diet also places more firm time limits and restrictions on cruciferous vegetables, nuts, alcohol, and raw fruits and vegetables than the low FODMAP diet or the SCD.

Why we have concerns with SSFG diet

Lack of evidence

No research studies are available to support the use of the SSFG for any disease process, including SIBO. The lack of evidence means that the SSFG can only be described as a diet theory or potential symptom management aid for SIBO. We are hesitant to suggest diet strategies with no clinical studies substantiating their use for any disease process. 

Highly Restrictive

While the SSFG aims to starve out SIBO, but we feel this diet may starve people in general. We are not convinced that the potential pros of such a highly restrictive diet outweigh the exceptional risks of malnutrition.

We feel the diet’s restrictive nature is likely to result in inadequate calorie intake and nutrient deficiencies. For example, depending on individual tolerance, the diet may restrict all dairy foods and calcium-fortified alternatives like soy milk or nut milks. The diet also restricts calcium-rich cruciferous vegetables during the introductory and intermediate phases, with the intermediate phase lasting for up to 3 months. 

As if this all wasn’t restrictive enough, the recommendation to eat pureed or cooked fruits and vegetables only during the 1-3 month intermediate phase is a recommendation we find questionable at best. We’ve previously taken research deep-dives into diet strategies that promote soft-cooked, low fiber foods. We’ve found that choosing cooked foods to aid digestion is a practice based more on theory than loads of scientific evidence. 

Most often, diets based around cooked foods are brief interventions abandoned as soon as tolerance of a more broad diet is demonstrated. A 1-3 month time frame of eating only cooked foods would lead to an even more compromised nutrition status. For instance, nutrients such as vitamin C are partially destroyed by heat. Vitamin C is essential for collagen production, immune health, antioxidant functions, metabolism of proteins, and the creation of certain neurotransmitters. S 

Moreover, with so many fermentable compounds restricted, fiber adequacy would also be next to impossible to achieve on the SSFG. This may not sound like that big of a deal, but we assure you it is.

Even as dietitians who have received training through Monash University for the low FODMAP diet, our heads were spinning, trying to make sense of how to apply the SSFG. The diet is highly confusing and restrictive. The mental gymnastics required to make the diet nutritionally adequate were a nightmare for us even to imagine. We struggled to envision someone without significant training in nutrition implementing the diet in a nutritionally balanced way. 

Lack of Clear Guidelines

To even write about the SSFG, we had to make several assumptions about the diet’s application. Siebecker gave no clear directives about when and how to do the introductory diet. Similarly, no guidance beyond following the intermediate phase of the diet for 1-3 months was given. 

Even more concerning, there is no clear end-goal for the diet, and the duration of the final stage of the diet is not specified. Siebecker’s vague instructions for testing foods for intolerance were also woefully inadequate.

Any elimination diet designed to spot intolerances should be highly structured so that symptom response to a given food is unmistakable. 

We feel this diet is likely to be carried out for an excessive duration given the lack of guidance. We also call into question the ability to correctly spot food triggers and sensitivities, given that there is no guidance offered on reintroducing foods and monitoring symptoms. We believe this could lead to the diet being unnecessarily restrictive for a prolonged time. 

Risks of Disordered Eating Patterns

A highly restrictive diet without studies, clear guidance, or time points for implementation screams of being a disordered eating pattern re-packaged as a diet therapy. We would strongly caution against this diet approach for anyone, but particularly those with a history of disordered eating behaviors. 

Monash University notes that a disqualifier for following a low FODMAP diet is a history of disordered eating patterns. Given that this diet is even more restrictive than a low FODMAP diet, we believe the same should be true under these circumstances. 

Our verdict 

• The SIBO Specific Food Guide (SSFG) restricts more fermentable carbohydrates than the low FODMAP diet or the Specific Carbohydrate Diet (SCD). 
• We do not believe the use of the SSFG for the treatment or management of SIBO is a great idea for the following reasons: 
• No studies are available on the SSFG for any disease process, including SIBO.
• The diet is highly restrictive and is likely to predispose to malnutrition or disordered eating behaviors. 
• The diet lacks clear guidance on implementation and duration for its use.