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Recommendations Summary

CF: Food Intake with Comorbidities (CF-Related Diabetes and Overweight/Obesity) 2020

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.

  • Recommendation(s)

    CF: Food Intake with CF-Related Diabetes

    For all individuals with cystic fibrosis-related diabetes (CFRD), it is reasonable for the RDN or international equivalent to consider advising a diet consistent with general, age-appropriate healthy dietary recommendations and individualize as needed according to CFRD pathology. It is reasonable for the RDN to emphasize limiting high-sugar foods and beverages with low nutrient density, due to adverse effects on blood glucose levels.

    Rating: Consensus

    CF: Food Intake with Overweight/Obesity

    For individuals with cystic fibrosis (CF) who are overweight or obese, it is reasonable for the RDN or international equivalent to advise an age-appropriate diet that emphasizes foods associated with positive health outcomes in the general population, including vegetables, fruits, whole grains, seafood, eggs, beans and peas, nuts and seeds, dairy products, and meats and poultry, as tolerated and preferred by the individual with CF, with energy needs adjusted to achieve or maintain normal growth (pediatrics) or BMI status (adults).

    Rating: Consensus

    • Risks/Harms of Implementing This Recommendation

      Individuals with cystic fibrosis (CF) are at risk of malnutrition, and any dietary restrictions should be carefully considered and discussed with the individual with CF and family before being advised and implemented.

    • Conditions of Application

      CFRD. Due to high nutrient needs in individuals with cystic fibrosis (CF), exclusion of sweet foods may not be warranted for some individuals with CFRD. In these cases RDNs can encourage consumption of sweet foods with nutritive value (such as chocolate with nuts or desserts with fruit) or in combination with foods with nutritive values (i.e. containing fat, protein, fiber and/or micronutrients) (Saxby et al 2017). Consuming foods or beverages in isolation that are high in sugar and low in other nutrients can result in adverse effects to blood glucose levels. Dietary carbohydrate intake can be managed by adjusting insulin dose according to individual response as well as carbohydrate amount and meal/snack nutrient composition. If an individual has a continuous glucose monitoring system prescribed by an endocrinologist, data can be used to elucidate patterns in blood glucose response and inform diet prescription.

      Overweight/Obesity. In individuals with CF who are overweight or obese, as for all other individuals, the RDN should assess multiple aspects of nutrition status (see Nutrition Assessment section) and discuss lifestyle patterns as well as values and goals with the individual with CF and family before advising a nutrition prescription. While slow weight loss based on transitioning to a healthy diet may be warranted for some individuals who have experienced weight gain, particularly due to changes in medications, weight loss may be discouraged in some individuals, for example if weight loss appears to result in loss of fat free mass and declining pulmonary function. RDNs must use clinical expertise and co-produce dietary advice with the individual with CF and the interdisciplinary healthcare team.

    • Potential Costs Associated with Application

      Foods that are healthy and optimize health are generally easily accessible, but socioeconomic and environmental factors, including food insecurity, should be considered and addressed when advising individuals with CF how to improve their dietary intake. The costs of implementing dietary counseling for overweight and obesity in a setting that has traditionally focused on undernutrition only is unclear.

    • Recommendation Narrative


      Background. CFRD is the most common comorbidity in CF, with approximately 35-50% of people with CF affected by CFRD (Moran et al 2018). Management of CFRD can be particularly challenging due to the high risk of malnutrition as well as the progressive nature of pancreatic insufficiency in individuals with CF.

      Evidence. CFRD increases progression of pulmonary dysfunction in pediatric individuals with CF (Goss et al 2018, Welsh et al 2014, Chamnan et al 2010) and increases risk of pulmonary dysfunction and  mortality in adults with CF (Academy of Nutrition and Dietetics 2019, Gosset al 2018, Amadori et al 2009, Ramos et al 2017, George et al 2011, Chamnan et al 2010). Despite the prevalence of this co-morbidity, there were no primary research articles identified for the systematic review supporting this guideline that specifically examined the relationships between diet and CFRD-related outcomes in pediatric or adult individuals with CFRD. A cross-sectional study published in 2019 (after the cut-off of systematic review) examined the relationship between dietary intake and anthropometric and body composition outcomes in 24 adults with CF, 46% of whom had CFRD, and 25% of whom had impaired glucose tolerance. There were no significant relationships between intake of macronutrients, types of fat, added sugars, whole grains or Healthy Eating Index (HEI)-2015 score and fasting glucose levels. However, both added sugar intake and fasting glucose levels were both significantly associated with visceral adipose tissue (Bellissimo et al 2019). In a second cross-sectional study published in 2019, continuous blood glucose monitoring indicated that dietary glycemic index and glycemic load were significantly positively associated with amount of time spent with blood in the hyperglycemic range, and larger glucose fluctuations, respectively in 18 adults with CF (Armaghanian et al 2019).

      Current consensus guidelines on CFRD in children and adolescents recommend that individuals with CFRD should follow nutrition guidelines for all individuals with CF and should aim to achieve plasma glucose levels consistent with all people with diabetes as recommended by the American Diabetes Association, with goals individualized as appropriate. Specific recommendations regarding insulin therapy for individuals with CF are outside of the scope of this guideline. However, education for individuals with CFRD should focus on self-management of glycemic control and insulin therapy, adequacy of energy intake and aerobic exercise (Turcket al 2016, Moran et al 2018). Intake of food and beverages with high added sugar content and without other nutrients to counter rapid spikes in blood glucose (such as fat, protein or fiber) should generally be discouraged. The recommendation to avoid large quantities of high sugar foods and beverages with low nutrient density is supported by current consensus guidelines (Moran et al 2018). In addition, RDNs should consider the appropriateness of candy without nutritive value (i.e. without protein, fat or micronutrients) for individuals with CF, since these foods may adversely affect blood glucose levels as well as displace foods with higher nutrient content.



      Background. Overweight and obesity (Division of Nutrition 2019, Division of Nutrition 2019) traditionally have not been a concern for individuals with CF, since the primary nutrition challenge has been under-nutrition due to increased energy expenditure and decreased nutrient absorption. However, as CF treatments have improved, incidence of overweight and obesity have increased in the CF population, with 30.4% of adults with class IV-V mutations, which constitute 14% of adults in the registry, classified as overweight and 21.1% classified as obese (Cystic Fibrosis Patient Registry 2017). Other center-specific estimates of overweight/obesity prevalence in the CF population range from 13-18% (Panagopoulou et al 2014, Hanna et al 2015). In Spanish hospitals, rates were lower, at 6% (Gonzalez Jimenez et al 2017). Individuals with CF who are more likely to be overweight or obese are those who are older and male, have less severe genotypes, better lung function and are pancreatic sufficient (Stephenson et al 2013).

      Individuals with CF who are overweight or obese may be more likely to have higher circulating total and LDL cholesterol levels (Gonzalez Jimenez et al 2017, Coderre et al 2012) and higher fasting blood insulin levels and insulin AUC (Coderreet al 2012). In the general population, incidence of overweight and obesity is associated with several adverse health outcomes including cardiovascular diseases, diabetes, osteoarthritis and some types of cancers (World Health Organization 2018). These chronic conditions have not been widely recognized as problematic for individuals with CF in the past.  However, improved treatments for CF require consideration of long-term nutrition status as individuals look forward to aging with CF.

      Evidence. There were no studies included in the systematic review that examined how diet affected nutrition-related outcomes in pediatric or adult individuals with CF who are overweight or obese. While some evidence suggests that overweight status may be protective against pulmonary decline in adults (Goss et al 2018), other evidence suggested no difference in pulmonary decline according to overweight status in adult (Welsh et al 2014, Stephenson et al 2015) or pediatric participants (Lai et al 2009, Sanders et al 2015, Sanders et al 2018). However, BMI alone, which is typically used to classify overweight and obesity, does not describe body composition, which may be a stronger predictor of pulmonary function in adults (Alvarez et al 2016).

      Weight and Dietary Goals. It is unclear if individuals with CF who are overweight or obese should be encouraged to attain a normal weight status. However, any kind of rapid weight loss or extreme weight loss plans should be discouraged in individuals with CF, since it is unclear if this would result in detrimental pulmonary effects or loss of fat free mass. Individuals who begin treatments that lead to weight gain may have difficulty transitioning to a diet that emphasizes healthy foods, especially if the individual has historically focused intake on a high-fat, high-energy diet. RDNs must work with individuals with CF and their families to determine motivations and goals that will improve nutrition status and quality of life over time. Incorporation of healthy eating principles can be beneficial for all members of the family of an individual with CF. Communicating nutrition messages that are consistent with those for the general population can decrease burden of adhering to a special diet.

    • Recommendation Strength Rationale

      This recommendation is based on expert consensus/opinion, supporting evidence and dietetic/nutrition science principles since there was no evidence included in the systematic review that examined the relationships between intake of foods or food groups, dietary patterns or meal patterns on nutrition-related outcomes in individuals with CFRD or overweight/obesity.

    • Minority Opinions

      Consensus reached. 

  • Supporting Evidence

    The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).

    In participants with CF, what is the relationship between dietary intake of food groups, dietary patterns and meal frequency and nutrition-related outcomes?

    • References
    • References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process

      • Academy of Nutrition and Dietetics Evidence Analysis Library. "In individuals with CF, what is the longitudinal relationship (at least 3 months) between weight and growth parameters and FEV1?". Evidence Analysis LIbrary Cystic Fibrosis Systematic Review web site. Updated August 2019. Accessed September 10, 2019.
      • Armaghanian N, Atkinson F, Taylor N, et al. Dietary intake in cystic fibrosis and its role in glucose metabolism. Clin Nutr. 2019.
      • Alvarez JA, Ziegler TR, Millson EC, Stecenko AA. Body composition and lung function in cystic fibrosis and their association with adiposity and normal-weight obesity. Nutrition. 2016;32(4):447-452.
      • Amadori A, Antonelli A, Balteri I, Schreiber A, Bugiani M, De Rose V. Recurrent exacerbations affect FEV(1) decline in adult patients with cystic fibrosis. Respir Med. 2009;103(3):407-413.
      • Bellissimo MP, Zhang I, Ivie EA, et al. Visceral adipose tissue is associated with poor diet quality and higher fasting glucose in adults with cystic fibrosis. J Cyst Fibros. 2019;18(3):430-435.
      • Chamnan P, Shine BSF, Haworth CS, Bilton D, Adler A, I. a. Diabetes as a determinant of mortality in cystic fibrosis. Diabetes care. 2010;33(2):311-316.
      • Coderre L, Fadainia C, Belson L, et al. LDL-cholesterol and insulin are independently associated with body mass index in adult cystic fibrosis patients. J Cystic Fibros. 2012;11(5):393-397.
      • Cystic Fibrosis Foundation Patient Registry. 2017 Annual Data Report. Available at: Accessed October 15, 2019.
      • Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion. Defining Adult Overweight and Obesity. Published 2019. Updated April 11, 2017. Accessed November 27, 2019.
      • Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion. Defining Childhood Obesity.
      • George PM, Banya W, Pareek N, et al. Improved survival at low lung function in cystic fibrosis: cohort study from 1990 to 2007. BMJ (Clinical research ed). 2011;342(8900488):d1008.
      • Gonzalez Jimenez D, Munoz-Codoceo R, Garriga-Garcia M, et al. Excess weight in patients with cystic fibrosis: is it always beneficial?. Nutricion Hospitalaria. 2017;34(3):578-583.
      • Goss CH, Sykes J, Stanojevic S, et al. Comparison of nutrition and lung function outcomes in patients with cystic fibrosis living in Canada and the United States. Am J RespirCrit Care Med. 2018;197(6):768-775.
      • Hanna RM, Weiner DJ. Overweight and obesity in patients with cystic fibrosis: a center-based analysis. Pediatr Pulmonol. 2015;50(1):35-41.
      • Lai HJ, Shoff SM, Farrell PM, et al. Recovery of birth weight z score within 2 years of diagnosis is positively associated with pulmonary status at 6 years of age in children with cystic fibrosis. Pediatrics. 2009;123(2):714-722.
      • Moran A, Pillay K, Becker D, Granados A, Hameed S, Acerini CL. ISPAD Clinical Practice Consensus Guidelines 2018: Management of cystic fibrosis-related diabetes in children and adolescents. Pediatr Diabetes. 2018;19 Suppl 27:64-74.
      • Panagopoulou P, Fotoulaki M, Nikolaou A, Nousia-Arvanitakis S,  A. Prevalence of malnutrition and obesity among cystic fibrosis patients. Pediatr Int. 2014;56(1):89-94.
      • Ramos KJ, Quon BS, Heltshe SL, et al. Heterogeneity in survival in adult patients with cystic fibrosis with FEV1 < 30% of predicted in the United States. Chest. 2017;151(6):1320-1328.
      • Sanders DB, Fink A, Mayer-Hamblett N, et al. Early life growth trajectories in cystic fibrosis are associated with [ulmonary function at age 6 years. J Pediatrics. 2015;167(5):1081-1088.e1081.
      • Sanders DB, Zhang Z, Farrell PM, Lai HJ, CF Neonatal Screening Group W. Early life growth patterns persist for 12 years and impact pulmonary outcomes in cystic fibrosis. J Cystic Fibros. 2018(101128966).
      • Saxby N. PC, Kench A., King S., Crowder T., van der Haak N. and the Australian and New Zealand Cystic Fibrosis Nutrition Guideline Authorship Group. Nutrition Guidelines for Cystic Fibrosis in Australia and New Zealand. In. Sydney: Thoracic Society of Australia and New Zealand; 2017.
      • Stephenson AL, Mannik LA, Walsh S, et al. Longitudinal trends in nutritional status and the relation between lung function and BMI in cystic fibrosis: a population-based cohort study. Am J Clin Nutr. 2013;97(4):872-877.
      • Stephenson AL, Tom M, Berthiaume Y, et al. A contemporary survival analysis of individuals with cystic fibrosis: a cohort study. Eur Respir J. 2015;45(3):670-679.
      • Turck D, Braegger CP, Colombo C, et al. ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis. Clinical Nutrition (Edinburgh, Scotland). 2016;35(3):557-577.
      • Welsh L, Robertson CF, Ranganathan SC. Increased rate of lung function decline in Australian adolescents with cystic fibrosis. Pediatric Pulmonol. 2014;49(9):873-877.
      • World Health Organization. Obesity and overweight. World Health Organization. Published 2018. Accessed September 11, 2019.