Dietary Carbohydrate and Internal Body Fat (CARBFUNC)

April 23, 2021 updated by: Haukeland University Hospital

Dietary Carbohydrate and Internal Body Fat Mass in Women and Men With Obesity

This is a 2-year randomized controlled trial to test the effect of dietary carbohydrates, both quality and quantity, on changes in internal body fat mass. Up to 250 women and men with obesity are recruited in Bergen, Norway, and randomized to one of the following normo- and isocaloric dietary patterns (same amount of protein, polyunsaturated fatty acids and moderate energy, 2,000 - 2,500 kcal per day): 1) a low-fat high-carbohydrate diet primarily with refined (e.g., flour-based) carbohydrate sources, 2) a low-fat high-carbohydrate diet based on minimally refined (e.g., cellular) carbohydrate sources, and 3) a very-high-fat low-carbohydrate diet.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Obesity, and high internal fat storage in particular, represents a tremendous and increasing health challenge across the world, and is linked to the recent introduction and globalization of an ultra-processed food supply largely based on refined carbohydrates. However, more high-quality studies are needed to directly assess the role of carbohydrate quality in abdominal adiposity. We also need studies with greater long-term adherence to prescribed food profiles, which may be achievied with the help of new electronic tools such as meal planning applications.

The participants select and plan all meals among a list of carefully designed options, using an application/recipe booklet developed for the study. Each recipe/meal/snack is designed to fully comply with the overall macronutrient- and dietary profile for the respective groups. We will further instruct the participants to record their meal choices during three days every 14 days, and to record all deviations throughout the intervention.

Enrolled participants are invited to study visits at baseline and after 3, 6, 9, 12 and 24 months. At all or some of these time points, the participants provide biological samples (blood, urine and feces, and for some, adipose and/or muscle tissue) and undergo phenotyping, e.g., measurement of body weight and fat mass by bioelectrical impedance analysis and low-radiation CT imaging, and a standardized meal test with blood sample collection up to 4 hours postprandially. In addition, participants will be asked to fill out a collection of questionnaires that assess quality of life, motivation, fatigue, gastrointestinal health, appetite and physical activity. We ask the participants to maintain the same level of physical activity throughout the study.

The primary outcome measure is change in internal body fat mass (visceral adipose tissue) measured by CT imaging. Secondary outcome measures include change in 2-hour postprandial serum concentrations of insulin, change in 4-hour postprandial serum concentrations of triacylglycerols, and change in fecal microbiota composition measured by 16S sequencing.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
150

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Norway
      • Bergen, Norway, 5021
        • Forskningsenhet for helseundersøkelser (research unit for clinical trials), Department of Clinical Science, University of Bergen

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

20 years to 55 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Body-mass index (BMI) equal to or above 30 kg/m2 and/or waist circumference equal to or above 102 cm for men and 88 cm for women
  • Weight stable during the last 2 months before start of the study (less than 5 % change in body weight up or down)
  • No known diabetes or consumption of diabetes medication
  • Desire to follow a specified dietary pattern using specific recipes throughout the time of the study period
  • Ability to periodically record food intake using a specially designed app for the study

Exclusion Criteria:

  • Use of statins and/or diabetes medication
  • Recent surgical or antibiotics treatment during the last 2 months before start of the study
  • Chronic inflammatory bowel disease
  • Serious disease
  • Smoking
  • Pregnancy or breast feeding
  • Alcohol consumption during the study of more than 2 alcohol units per day (1 unit = 15 ml (12.8 g) pure alcohol)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: TREATMENT
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: NONE

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
ACTIVE_COMPARATOR: Acellular carbohydrate diet
Prescribed dietary pattern. Carbohydrates from acellular sources, e.g., refined flour/bakery products, at least 500 grams of fruits/vegetables per day, and a macronutrient composition within typical nutritional recommendations for the general population.
Behavioral: Acellular carbohydrate diet
Participants will be asked to consume 2,000 - 2,500 kcals, thereof 45 energy percent (E%) carbohydrate (up to 5 E% added sugar), 30 E% fat (10-12 E% saturated fatty acids and 7-10 E% polyunsaturated fatty acids) and 17 E% protein. They will use an original online/smartphone application that provides choices of meals/food combinations/recipes corresponding to their prescribed macronutrient profile and dietary pattern. Participants are asked to complete 3-day dietary records every 14 days throughout the study, and to report any deviations from the planned interventions.
EXPERIMENTAL: Cellular carbohydrate diet
Prescribed dietary pattern. Carbohydrates from cellular sources, e.g., root vegetables, fruits, whole-grain rice, non-flour grain products, at least 500 grams of fruits/vegetables per day, and a macronutrient composition within typical nutritional recommendations for the general population similar to the acellular carbohydrate diet.
Behavioral: Cellular carbohydrate diet
Participants will be asked to consume 2,000 - 2,500 kcals, thereof 45 energy percent (E%) carbohydrate (up to 1 E% added sugar), 38 E% fat (10-12 E% saturated fatty acids and 7-10 E% polyunsaturated fatty acids) and 17 E% protein. They will use an original online/smartphone application that provides choices of meals/food combinations/recipes corresponding to their prescribed macronutrient profile and dietary pattern. Participants are asked to complete 3-day dietary records every 14 days throughout the study, and to report any deviations from the planned interventions.
EXPERIMENTAL: Low-carbohydrate high-fat diet
Prescribed dietary pattern. Energy largely from fat, cellular carbohydrate sources, and otherwise similar food types as in the acellular/cellular carbohydrate diets including at least 500 grams of fruits/vegetables per day.
Behavioral: Low-carbohydrate high-fat diet
Participants will be asked to consume 2,000 - 2,500 kcals, thereof 10 energy percent (E%) carbohydrate (up to 1 E% added sugar), 73 E% fat (30 E% saturated fatty acids and 7-10 E% polyunsaturated fatty acids) and 17 E% protein. They will use an original online/smartphone application that provides choices of meals/food combinations/recipes corresponding to their prescribed macronutrient profile and dietary pattern. Participants are asked to complete 3-day dietary records every 14 days throughout the study, and to report any deviations from the planned interventions.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in internal body fat
Time Frame: Baseline and 6, 12 and 24 months
Visceral fat mass (cm3) measured by computed tomography (CT) imaging
Baseline and 6, 12 and 24 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in postprandial insulin
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating insulin concentrations measured before and 2 hours after intake of a standardized mixed meal
Baseline and 3, 6, 9, 12 and 24 months
Change in postprandial C-peptide
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating C-peptide concentrations measured before and 2 hours after intake of a standardized mixed meal
Baseline and 3, 6, 9, 12 and 24 months
Change in postprandial triacylglycerol
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Triacylglycerol concentrations measured before and 4 hours after intake of a mixed meal
Baseline and 3, 6, 9, 12 and 24 months
Change in postprandial area under the curve (AUC) glucose
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating glucose measured before and after 30, 60, 90, 120 and 240 minutes after intake of a standardized mixed meal
Baseline and 3, 6, 9, 12 and 24 months
Change in postprandial non-esterified fatty acids
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating non-esterified fatty acid concentrations before and after 60, 120 and 240 minutes after intake of a standardized mixed meal
Baseline and 3, 6, 9, 12 and 24 months
Change in fecal microbiome composition
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Microbiome composition measured by 16S sequencing
Baseline and 3, 6, 9, 12 and 24 months
Change in liver density
Time Frame: Baseline and 6, 12 and 24 months
Calculated as liver/spleen attenuation index (Hounsfield units) based on quantification by computed tomography (CT) imaging
Baseline and 6, 12 and 24 months
Change in pericardial fat mass
Time Frame: Baseline and 6, 12 and 24 months
Pericardial fat mass (cm3) measured by computed tomography (CT) imaging
Baseline and 6, 12 and 24 months
Change in abdominal subcutaneous fat mass
Time Frame: Baseline and 6, 12 and 24 months
Abdominal subcutaneous fat mass (cm3) measured by computed tomography (CT) imaging
Baseline and 6, 12 and 24 months
Change in coronary artery calcification (CAC)
Time Frame: Baseline and 6, 12 and 24 months
CAC score calculated based on computed tomography (CT) imaging
Baseline and 6, 12 and 24 months
Change in waist circumference
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Waist circumference (cm) measured by a measuring tape
Baseline and 3, 6, 9, 12 and 24 months
Change in body-mass index
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Body-mass index measured as body weight (kg) divided by height (m) squared
Baseline and 3, 6, 9, 12 and 24 months
Change in fasting insulin
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting insulin concentrations
Baseline and 3, 6, 9, 12 and 24 months
Change in fasting C-peptide
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting C-peptide concentrations
Baseline and 3, 6, 9, 12 and 24 months
Change in fasting TAG
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting triacylglycerol concentrations
Baseline and 3, 6, 9, 12 and 24 months
Change in fasting HDL cholesterol
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting high-density lipoprotein cholesterol (HDL-C)
Baseline and 3, 6, 9, 12 and 24 months
Change in TAG/HDL-C ratio
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
The ratio of circulating fasting triacylglycerol (TAG) and high-density lipoprotein cholesterol (HDL-C)
Baseline and 3, 6, 9, 12 and 24 months
Change in fasting LDL cholesterol
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting low-density lipoprotein cholesterol (LDL-C)
Baseline and 3, 6, 9, 12 and 24 months
Change in apolipoprotein profile
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating fasting apolipoprotein profile measured by multiplex ELISA
Baseline and 3, 6, 9, 12 and 24 months
Change in circulating and urine metabolites associated with one-carbon metabolism
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Circulating metabolites in the serine, glycine and histidine pathways measured in the fasted state by GC-MS/MS
Baseline and 3, 6, 9, 12 and 24 months
Change in total fat mass
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Total fat mass measured by bioimpedance analysis (BIA)
Baseline and 3, 6, 9, 12 and 24 months
Change in lean mass
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Lean mass will be measured by bioimpedance analysis (BIA)
Baseline and 3, 6, 9, 12 and 24 months
Change in appetite/fullness
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Subjective appetite and fullness assessed and quantified by the VAS questionnaire
Baseline and 3, 6, 9, 12 and 24 months
Change in gastrointestinal symptoms by the Roma III questionnaire
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
Gastrointestinal health will be surveyed and quantified by a questionnaire (Rome III Diagnostic Criteria for Irritable Bowel Syndrome (IBS)). The questionnaire surveys criteria for diagnosis of IBS within a 12-week period. The criteria for IBS are based on recurrent abdominal pain or discomfort, 3 days per month in the last 3 months (12 weeks), associated with ≥2 of the following criteria: 1.Improvement with defecation; 2. Onset associated with a change in stool frequency; 3. Onset associated with a change in stool form (appearance). The criteria are fulfilled with symptoms onset 6 months prior to diagnosis.
Baseline and 3, 6, 9, 12 and 24 months
Change in gastrointestinal symptoms by the IBS-SSS questionnaire
Time Frame: Baseline and 3, 6, 9, 12 and 24 months

Gastrointestinal health will be surveyed by the IBS-SSS questionnaire. Scores on the IBS-SSS range from 0 to 500 with higher scores indicating more severe symptoms. Subjects can be categorized as having mild (75-175), moderate (175-300), or severe (>300) IBS. A decrease of 50 points is associated with a clinically meaningful improvement. Each question on the VAS ranges from 0-100mm, where higher score indicates more severe symptoms.

The categorization based on scores (total possible score = 500) are as follows:

0-75 = not IBS 75-175= mild IBS 175-300 = moderate IBS 300-500 = severe IBS
Baseline and 3, 6, 9, 12 and 24 months
Change in fatigue
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
The Fatigue Impact Scale will be used to compute a total score for fatigue by summing up the scores for subclasses as follows: cognitive functioning (10 items, subscale range: 0-40), physical functioning (10 items, subscale range: 0-40), and psychosocial functioning (20 items, subscale range: 0-80). The statements are ranged on a five-level scale (0 = no problem to 4 = extreme problems), giving a maximum total FIS score of 160 (total scale range: 0-160) where low scores indicate less fatigue-related issues.
Baseline and 3, 6, 9, 12 and 24 months
Change in perception of health / quality of life
Time Frame: Baseline and 3, 6, 9, 12 and 24 months

Obesity-specific quality of life is measured with "Patient-Reported Outcomes in Obesity" (PROS), which consists of 8 items tapping how different life domains are affected by obesity. PROS have one overall score, ranging from 0 (optimal) to 3 (poorest).

Generic health-related quality of life is measured with RAND-36, which consists of dimensions ranging from 0 (poorest) to 100 (optimal). There are 8 subscales; physical functioning, physical role functioning, bodily pain, general health, vitality, social functioning, emotional role functioning and mental health. In addition, RAND-36 also have 2 summary scores: the physical component summary (PCS) (tapping from physical functioning, physical role functioning, bodily pain and general health) and mental component summary (MCS) (tapping from vitality, social functioning, emotional role functioning and mental health).
Baseline and 3, 6, 9, 12 and 24 months
Change in quality of life related to gastrointestinal symptoms
Time Frame: Baseline and 3, 6, 9, 12 and 24 months
The SF-NDI (Short-Form Nepean Dyspepsia Index (SF-NDI)) questionnaire will be used to assess quality of life / psychological wellbeing related to gastrointestinal symptoms. The 10-item SF-NDI was constructed and validated in patients with functional gastrointestinal disorders for measuring health-related quality of life. The 10-item short form includes five subscales: tension, interference with daily activities, eating/drinking, knowledge/control, and work/study, and each subscale contains two items. The items were measured by a 5-point graded Likert scale from 1 to 5. A total sum score for quality of life and a sum score for each of the five subscales were calculated by adding up scores for each item (range of total quality of life, 10-50; range of each subscale, 2-10). Higher scores indicate worse functioning or symptoms.
Baseline and 3, 6, 9, 12 and 24 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Haukeland University Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Bergen

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Simon N Dankel, PhD, University of Bergen
  • Study Director: Gunnar Mellgren, MD PhD, Haukeland University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 3, 2018

Primary Completion (ACTUAL)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 20, 2020

Study Completion (ACTUAL)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 24, 2021

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 23, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 9, 2018

First Posted (ACTUAL)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 17, 2018

Study Record Updates

Last Update Posted (ACTUAL)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 26, 2021

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 23, 2021

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2017/621

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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