Fiber and GLP-1: Why Type, Dosage, and Matrix Matter in Formulation
Adding fiber to a food or beverage may seem like a simple decision. In practice, however, changing the type of ingredient or increasing the amount by just a few grams per serving can alter viscosity, affect beverage flowability, or cause gastrointestinal discomfort for consumers.
This challenge becomes even more relevant with the growing use of GLP-1-based therapies. These medications suppress appetite and may reduce energy intake, while also being associated with gastrointestinal side effects such as nausea, diarrhea, and constipation.
For the food industry, a clear opportunity is emerging: developing products with higher nutritional density in smaller portions. However, there is also a risk in treating the simple addition of fiber as a sufficient solution.
There is no one-size-fits-all fiber for this market. Solubility, viscosity, fermentability, water retention, dosage, and food matrix all determine both the nutritional outcome and the product's industrial performance.
A market that is beginning to reshape food formulation
Strategy&, a consulting firm within the PwC network, estimates that the Brazilian GLP-1 medication market will grow from US$2 billion in 2025 to US$9 billion by 2030. This is a projection, not growth that has already occurred, but it helps illustrate the expected pace of expansion for this category in the country.[1]
The impact is also beginning to emerge in retail. In a survey presented at APAS Show 2026, Scanntech combined consumer trend research with purchasing behavior analysis.
Among people using these medications, 61% reported a significant reduction in appetite, 49% said they were making healthier food choices, and 47% reported increasing their protein intake.[2]
These figures do not mean that all users will follow the same pattern, nor that every change in sales can be attributed exclusively to these medications. Income, price, weather, availability, and individual preferences continue to influence purchasing decisions.
The relevant signal for R&D is different: some consumers are shifting toward smaller portions, increasing the importance of each product's nutritional composition.
The global dietary fiber market also reflects this growing interest. A commercial estimate by Mordor Intelligence projects that the food fibers segment will grow from US$10.04 billion in 2026 to US$15.99 billion in 2031, representing a compound annual growth rate of 9.75%.[3]
As with any market report, these figures depend on the category definition and methodology used. Nevertheless, the trend is consistent with the growing number of product launches focused on digestive health and higher nutritional density.
What GLP-1 changes and what science has yet to demonstrate
Clinical trials show that semaglutide can reduce appetite and energy intake. The magnitude of this effect varies depending on the medication, dosage, treatment duration, and study design.[4]
This makes concerns about fiber intake plausible: when overall food consumption decreases, meeting daily fiber recommendations may become more difficult, particularly if the diet is already low in fruits, vegetables, legumes, and whole grains.
The World Health Organization recommends at least 25 grams of naturally occurring dietary fiber per day for people over the age of 10.[5]
However, it is important to distinguish plausibility from established evidence. A systematic review published in 2026 concluded that evidence remains limited regarding the best nutritional strategies for people treated with GLP-1 receptor agonists or dual GIP/GLP-1 receptor agonists.
The included trials frequently reported gastrointestinal symptoms but did not adequately assess clinically relevant nutritional deficiencies.[6]
Therefore, the correct message is not that every GLP-1 user will develop a fiber deficiency. What the evidence supports is that reduced food intake and the occurrence of gastrointestinal symptoms justify greater attention to dietary quality and the composition of products consumed by this population.
Constipation matters, but it does not have a single cause
Constipation is among the adverse events associated with GLP-1-based therapies.
A recent meta-analysis of 101 randomized trials found an incidence of 7.39% among treated participants and a 2.41-fold higher risk compared with placebo. However, results varied across the medications analyzed.[7]
The explanation goes beyond delayed gastric emptying. Lower food volume, insufficient hydration, previously low fiber intake, physical activity levels, medication dosage, and the rate of dose escalation can also influence intestinal transit.
For this reason, nutrition and obesity medicine organizations recommend that the management of these therapies include individualized nutritional assessment, adequate fluid and fiber intake, and symptom management by healthcare professionals.[8]
This clinical recommendation does not turn a fiber-enriched food into a treatment for constipation. For the food industry, it points to a relevant nutritional need — and highlights that every product must be formulated and marketed within the limits of available evidence and applicable regulations.
Fiber is not a single ingredient
The term "dietary fiber" encompasses ingredients with very different behaviors. Classifying fibers simply as soluble or insoluble is not enough to predict their final performance.
Three properties are particularly important:
Viscosity: indicates how much a fiber increases resistance to flow or forms a gel. It may contribute to certain physiological effects but can also affect body, flowability, and ease of consumption.
Fermentability: describes the extent to which a fiber is utilized by the gut microbiota. Fermentation can generate beneficial compounds but may also produce gas and discomfort in sensitive individuals.
Water retention and colonic persistence: influence hydration and stool bulk. For this effect, solubility alone is not enough; the fiber must maintain its functional properties throughout the gastrointestinal tract.
These properties explain why two fibers added at the same amount can produce different technological and physiological outcomes.
What the evidence on constipation actually shows
A systematic review and meta-analysis published in the American Journal of Clinical Nutrition evaluated 16 randomized clinical trials involving 1,251 adults with chronic constipation.
In the nine studies that measured treatment response as a binary outcome, 66% of participants receiving fiber responded to treatment, compared with 41% in the control groups.[9]
This is a relevant finding, but it needs to be considered in full:
There was considerable heterogeneity across the studies.
The effect was more consistent with psyllium.
Doses above 10 g per day showed better results than lower doses.
Treatment periods of at least four weeks were more favorable for certain outcomes.
Flatulence was more common in the groups receiving fiber.
This reinforces the importance of ingredient selection. The meta-analysis does not demonstrate that any fiber, at any dose, is sufficient to improve constipation. It was also not conducted specifically among users of GLP-1 medications.
One trial cited in this literature evaluated 24 g of pectin per day over four weeks in 80 adults with slow-transit constipation. Mean colonic transit time decreased from 80.3 to 60.2 hours.[10]
This is an interesting result, but it was obtained using a high dose in a specific clinical population. It should not be translated into a general recommendation for all fibers or applications.
How the main dietary fibers perform
Fiber type | Relevant characteristics | Evidence for constipation | Key considerations |
Psyllium | Soluble, gel-forming fiber with high water-holding capacity | One of the options with the most consistent clinical evidence | Can significantly increase viscosity; requires adequate hydration and dosage control |
Inulin and FOS | Fermentable fibers with prebiotic properties | Insufficient evidence to assume a consistent laxative effect | Fermentation, gas, and bloating may increase depending on dosage |
Polydextrose | Low-viscosity soluble fiber with good technological flexibility | Inconsistent results | Dosage, tolerability, and behavior within the food matrix must be validated |
Acacia gum | Soluble, fermentable, low-viscosity fiber | Emerging evidence, still insufficient for broad therapeutic claims | Specification, dosage, fermentation, and application objectives |
Fiber blends | Can combine complementary properties | Depend on the ingredients, proportions, and dosages used | Combining fibers does not guarantee greater efficacy or tolerability |
For example, in the case of polydextrose, a randomized trial using 8 or 12 g per day found no significant reduction in intestinal transit time or improvement in stool frequency or consistency in adults with constipation.[11]
This does not diminish its value as a formulation ingredient, but it does mean that technological flexibility should not be confused with proven clinical efficacy.
For acacia gum, a trial involving people with constipation-predominant irritable bowel syndrome found an increase in bowel movement frequency, but no significant improvement in stool consistency, fecal mass, or quality of life.[12]
The findings support further research into this fiber but do not justify broad claims about its ability to treat constipation.
Four decisions that cannot be considered separately
1. Define the intended function
Is the project aiming to meet a dietary fiber content claim? Reduce the impact on viscosity? Develop a product with prebiotic properties? Improve the nutritional composition of a smaller portion?
Each objective requires a different choice. A fiber suitable for a reconstituted powder may not be viable in a ready-to-drink beverage. Likewise, an ingredient that supports gut microbiota fermentation may not be the best option when the priority is improving stool consistency.
2. Calculate the dose per serving
In Brazil, the reference daily value for dietary fiber is 25 g.
Under the requirements of RDC 429/2020 and IN 75/2020, the claim "source of fiber" generally requires at least 10% of this value per serving — 2.5 g. For a "high fiber content" claim, the minimum is 20%, or 5 g per serving, subject to the other applicable product requirements.[13]
Meeting labeling criteria does not automatically mean reaching the dosage used in a clinical study.
A serving containing 2.5 g may meet the requirements for a nutritional claim, but it does not reproduce results obtained with more than 10 or 20 g per day.
3. Test the fiber within the actual food matrix
The same fiber can behave differently in water, acidic beverages, dairy products, gummies, bars, or powdered supplements.
pH, temperature, shear, total solids, and interactions with proteins and minerals all influence dispersion, texture, and stability.
For this reason, technical data sheets and scientific literature are starting points, not final answers. The formulation must undergo processing tests, sensory evaluation, and stability monitoring in its packaging and under the intended commercial conditions.
4. Assess tolerability without making therapeutic claims
Gastrointestinal discomfort depends on the type of fiber, dosage, habitual intake, and individual sensitivity. Rapidly increasing fiber intake can cause gas and bloating, even with ingredients generally considered well tolerated.
For foods and supplements, marketing communications must remain within the scope of permitted claims. Brazil's National Health Surveillance Agency (Anvisa) makes it clear that supplements are not medicines and cannot be presented as products intended to prevent, treat, or cure diseases.
Specific benefits may only be communicated when authorized and under the established conditions.[14]
Therefore, stating that a product contains fiber or meets the requirements for a "source of fiber" claim is different from claiming that it treats constipation associated with GLP-1 use.
How the international market is responding
Some companies have already begun developing or repositioning products for this context, particularly in the United States.
In 2024, Nestlé announced Vital Pursuit, a meal range featuring smaller portions, protein, fiber, and micronutrients, designed for both GLP-1 medication users and people managing their weight.[15]
Conagra adopted a different strategy: it introduced the "On Track" badge across 26 Healthy Choice products that already met its internal criteria for protein, calories, and fiber. In this case, the company did not reformulate the foods; instead, it began highlighting the nutritional characteristics of existing products.[16]
Also in 2024, Smoothie King launched a smoothie menu in the United States featuring protein, fiber, and zero grams of added sugar, positioning it as an option for people using GLP-1 medications.[17]
These initiatives confirm commercial interest, but they do not establish a regulatory model for Brazil. Claims and direct references to medications must be assessed in accordance with Brazilian legislation and the specific product category.
From fiber selection to industrial validation
At Total Ingredientes, product development should start with the product itself, not with the predetermined selection of a fiber.
The first step is to define what the formulation needs to deliver: nutritional content, low viscosity, stability, a specific sensory profile, or a combination of these characteristics. Only then should the fiber type, required dosage, processing method, and food matrix be evaluated.
Among the alternatives worth exploring are acacia gum-based fibers, such as FibreGum B, as well as other solutions and blends suited to the project's objectives.
The suitability of each option must be confirmed in the actual application, considering dosage per serving, labeling requirements, processing, tolerability, sensory experience, and stability.
This approach helps avoid two common mistakes: selecting an ingredient based solely on its declared fiber content or attempting to replicate a clinical benefit without using the same fiber, dosage, and study conditions that demonstrated it.
More fiber does not necessarily mean a better formulation
The growth of GLP-1-based therapies is creating opportunities for foods and beverages with higher nutritional density in smaller portions. Fiber is part of this discussion, but it should not be treated as a homogeneous ingredient group or as a therapeutic solution for medication-related adverse effects.
A consistent product results from the combination of scientific evidence, dosage, food matrix, processing, sensory properties, stability, and regulatory compliance.
When these variables are considered from the outset, fiber becomes more than just a number on the label: it serves a well-defined purpose within the formulation.
Developing a food, beverage, or supplement with fiber?
Get in touch with the Total Ingredientes technical team to explore alternatives and identify the critical factors in your formulation.
This content is intended for technical and informational purposes only and does not replace medical or nutritional advice. Individuals using medication should remain under the supervision of the healthcare professionals responsible for their treatment.
References
Strategy& / PwC Brasil. The Weight of Weight-Loss Injections. 2026.
Scanntech. APAS Show 2026 Reveals the Impact of Weight-Loss Injections on Food Retail. 2026.
Mordor Intelligence. Food Fibers Market Size and Share Analysis — Growth Trends and Forecasts, 2026–2031.
Gabe, M. B. N. et al. Effect of oral semaglutide on energy intake, appetite, control of eating and gastric emptying in adults living with obesity. Diabetes, Obesity and Metabolism, 2024.
World Health Organization. Carbohydrate Intake for Adults and Children: WHO Guideline. 2023.
Paulo, M. S. et al. Dietary Strategies and Nutritional Management in Patients Receiving GLP-1 and Dual GIP/GLP-1 Receptor Agonists. Diabetes, Obesity and Metabolism, 2026.
Exploring the Rates of Gastrointestinal Adverse Effects Among Five GLP-1 Receptor Agonists: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. 2026.
Mozaffarian, D. et al. Nutritional Priorities to Support GLP-1 Therapy for Obesity: A Joint Advisory. The American Journal of Clinical Nutrition, 2025.
van der Schoot, A. et al. The Effect of Fiber Supplementation on Chronic Constipation in Adults. The American Journal of Clinical Nutrition, 2022.
Xu, L. et al. Clinical Benefits After Soluble Dietary Fiber Supplementation: A Randomized Clinical Trial in Adults with Slow-Transit Constipation. World Journal of Gastroenterology, 2015.
Ibarra, A. et al. Short-Term Daily Intake of Polydextrose Fiber Does Not Shorten Intestinal Transit Time in Constipated Adults. 2018.
Calame, W. et al. Acacia Fiber or Probiotic Supplements to Relieve Gastrointestinal Complaints in Patients with Constipation-Predominant IBS. 2024.
Anvisa. RDC 429/2020 and IN 75/2020 — Nutrition Labeling.
Anvisa. Frequently Asked Questions About Dietary Supplements.
Nestlé USA. Vital Pursuit: Support for GLP-1 Users and Weight Management. 2024.
Conagra Brands. On Track Badges on Select Healthy Choice Products. 2024.
Smoothie King. GLP-1 Support Menu. 2024.
