The Personalized Nutrition Study: Evaluation of a Genetically-informed Weight Loss Approach
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Enrollment
- 145
- Locations
- 1
- Primary Endpoint
- Percent Weight Change
Study Overview
Brief Summary
A person's genetic code is believed to affect how much weight he/she will lose during diets that vary in carbohydrate and dietary fat content. 'Carbohydrate responders' are hypothesized to lose more weight on diets that are high in carbohydrates, as compared to high in fats. 'Fat responders' are hypothesized to lose more weight on diets that are high in dietary fat, as compared to high in carbohydrates. The purpose of the proposed study is to test these hypotheses in a randomized controlled trial.
Detailed Description
Obesity and its comorbidities are major public health challenges. To combat the obesity pandemic, many weight-loss strategies have been studied, often emphasizing either high carbohydrate (low fat) diets or high fat (low carbohydrate) diets. Mean weight loss differences between high-carbohydrate and high-fat diets that induce equal caloric deficits have been reported to be small; however, the individual weight loss response varies substantially within diet groups, suggesting that different individuals react differently to high-carbohydrate or high-fat diets. This assumption is supported by retrospective data showing that participants with carbohydrate-responsive polymorphisms lost 2-3 times more weight when assigned to a high-carbohydrate diet compared to a high-fat diet, and vice versa for those with dietary fat-responsive polymorphisms. Conversely, a recent randomized clinical trial aimed to determine the effect of a healthy high-fat diet (high in unsaturated fats) vs. a healthy high-carbohydrate diet (high in whole-grain foods) on 12-month weight change but did not find significant differences between the two groups and failed to find the hypothesized association between genotype patterns and weight loss induced by diets that varied in fat and carbohydrate content. However, an important caveat of their approach is that the single nucleotide polymorphisms selected by the investigators had not been previously associated with obesity or with dietary responses, which may explain their lack of predictive value in identifying differences in inter-individual responses. In addition, the fat composition of the diets was relatively high in both high- and low-fat groups. The inconsistent findings in the literature indicate a need for further research to determine if genetic factors affect weight loss when exposed to diets that vary in carbohydrates and dietary fats.
The purpose of this randomized controlled parallel arm trial is to test the following hypotheses.
Hypothesis 1 will test if participants assigned to the diet that corresponds to their genotype lose more weight than those assigned to a diet inconsistent with their genotype.
Hypothesis 2 will analyze the fat responders and carbohydrate responders separately.
- Hypothesis 2a: Fat responders will lose more weight on the high-fat diet vs. the high-carbohydrate diet.
- Hypothesis 2b: Carbohydrate responders will lose more weight on the high-carbohydrate diet vs. the high-fat diet.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- Single (Outcomes Assessor)
Masking Description
Outcome assessors will be blind to diet assignment and genotype pattern. Interventionists will be blind to genotype pattern, but not diet type. To enhance external validity, participants will be told if they are carbohydrate or fat responders.
Eligibility Criteria
- Ages
- 18 Years to 75 Years (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •BMI ≥ 27.0 kg/m2 to < 47.5 kg/m2
- •Completed genealogy test and access to the raw data
- •Fat responder or Carbohydrate responder, as determined by genetic risk score
- •It is estimated that approximately 1/3 of people are fat responders, 1/3 are carbohydrate responders, and 1/3 are neither or will respond to either diet. Only carbohydrate and fat responders are eligible.
Exclusion Criteria
- •Current smoker or has smoked in the previous year
- •For females, pregnant or planned pregnancy during the study duration, or breast-feeding, based on self-report
- •Conditions, diseases, or medications that affect body weight or metabolism (e.g., certain antipsychotic medications; type 2 diabetes mellitus; heart failure; cancer, excluding certain melanomas; etc.)
- •Has gained or lost more than 10 pounds in the last 3 months
- •Currently diagnosed with an eating disorder, major depression, or other condition that, in the judgment of the investigators, could affect the risk to the participant or study completion
Arms & Interventions
Fat responders (1)
receiving high-fat diet
Intervention: High-fat diet (Behavioral)
Carbohydrate responders (1)
receiving high-fat diet
Intervention: High-fat diet (Behavioral)
Fat responders (2)
receiving high-carbohydrate diet
Intervention: High-carbohydrate diet (Behavioral)
Carbohydrate responders (2)
receiving high-carbohydrate diet
Intervention: High-carbohydrate diet (Behavioral)
Outcomes
Primary Outcomes
Percent Weight Change
Time Frame: Baseline to 12 weeks
Weight change (kg) / weight at baseline (kg) \* 100
Weight Change
Time Frame: Baseline to 12 weeks
Weight (kg) at 12 weeks minus weight at baseline (kg)
Secondary Outcomes
- Change in Food Cravings(Baseline to 12 weeks)
- Change in Fat Preference Index(Baseline to 12 weeks)
- Change in Disinhibition(Baseline to 12 weeks)
- Change in Hunger(Baseline to 12 weeks)
- Change in Cognitive Restraint(Baseline to 12 weeks)
- Change in Waist Circumference(Baseline to 12 weeks)
Investigators
Corby K. Martin
Professor
Pennington Biomedical Research Center