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The objective of this trial is to examine the long-term effects of a diet low in carbohydrates, as compared to one low in fat, on cardiovascular disease risk factors, including blood pressure (BP), body weight and composition, serum lipids, plasma glucose, insulin, adipocytokines (adiponectin, leptin, resistin), and C-reactive protein (CRP) among obese adults.
The investigators will test the following hypotheses:
Hypothesis 1: Compared to a low fat diet, a diet low in carbohydrates will reduce systolic and diastolic BP over 12 months; Hypothesis 2: Compared to a low fat diet, a diet low in carbohydrates will reduce body weight, total percent body fat, and waist circumference over 12 months; Hypothesis 3: Compared to a low fat diet, a diet low in carbohydrates will reduce serum levels of LDL-cholesterol and triglycerides and increase serum levels of HDL-cholesterol over 12 months; Hypothesis 4: Compared to a low fat diet, a diet low in carbohydrates will reduce plasma levels of glucose and insulin levels over 12 months; and Hypothesis 5: Compared to a low fat diet, a diet low in carbohydrates will reduce plasma levels of leptin, resistin, and CRP and increase plasma levels of adiponectin over 12 months.
Cardiovascular diseases (CVD) remain the leading cause of death globally as well as here in the United States. Manipulations of the macronutrient (protein, carbohydrate and fat) contents of diet have been used extensively for weight loss and weight control in the past several decades. Low carbohydrate diets, in particular, have gained popularity for weight loss. However, few studies have examined the effects of a diet low in carbohydrates on traditional and novel cardiovascular risk factors in the long term, particularly in contrast to the current dietary recommendations for decreased fat intake to reduce risk of CVD. In this proposal, we plan to conduct a 12-month, parallel-arm, randomized controlled trial of a diet low in carbohydrates versus the currently recommended low fat diet to reduce CVD risk factors among obese adults. The objective of this trial is to examine the long-term effects of a diet low in carbohydrates, as compared to one low in fat, on CVD risk factors, including blood pressure (BP), body weight and composition, serum lipids, plasma glucose, insulin, adipocytokines (adiponectin, leptin, resistin), and C-reactive protein (CRP) among obese adults. In order to accomplish these objectives we will randomize 130 eligible participants (n=65 in each group) to consume either a diet low in carbohydrates (≤40 g/d) or a diet low in fat (<7% saturated fat, <30% total fat). Neither of the diets will be energy-restricted. Participants will meet with a dietitian for one-on-one counseling sessions weekly for the first 4 weeks, then bi-monthly in small group sessions for the next 5 months, and monthly in larger group sessions for the final 6 months of the intervention. Data on both traditional and novel CVD risk factors will be collected at baseline, 3, 6, and 12 months. We hypothesize that a diet low in carbohydrates as compared to a diet low in fat will lower systolic and diastolic BP, body weight, total percent body fat, waist circumference, serum levels of triglycerides, and plasma levels of insulin, glucose, leptin, resistin, and CRP, and increase serum levels of HDL-cholesterol and adiponectin. Because CVD is the most common cause of death here in the U.S. and world-wide, this study has important public health implications. It will provide new information on the potential long-term effects of diets low in carbohydrates on both the traditional risk factors for CVD as well as novel risk factors and inflammatory factors. The results from this study will help to determine if a diet low in carbohydrates as compared to the currently recommended low fat diet can decrease the risk of CVD among obese adults.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| 1 | Experimental | low carbohydrate diet |
|
| 2 | Active Comparator | low fat diet |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| low carbohydrate diet | Behavioral | <40 grams carbohydrate/day |
| |
| low fat diet |
| Measure | Description | Time Frame |
|---|---|---|
| Predicted Mean Difference in Body Weight From Baseline, by Assigned Dietary Group | Predicted mean difference from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Lean Mass From Baseline, by Assigned Dietary Group | Mean Difference in Lean Mass predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Fat Mass From Baseline, by Assigned Dietary Group | Mean Difference in Fat Mass predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences of Waist Circumference From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Total Cholesterol Level From Baseline by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in LDL Cholesterol Level From Baseline, by Assigned Dietary Group |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Lydia A Bazzano, MD, PhD | Tulane University | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Tulane University, Office of Health Research | New Orleans | Louisiana | 70112 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 26803589 | Derived | Hu T, Yao L, Reynolds K, Niu T, Li S, Whelton P, He J, Bazzano L. The effects of a low-carbohydrate diet on appetite: A randomized controlled trial. Nutr Metab Cardiovasc Dis. 2016 Jun;26(6):476-88. doi: 10.1016/j.numecd.2015.11.011. Epub 2015 Dec 12. | |
| 25178568 | Derived | Bazzano LA, Hu T, Reynolds K, Yao L, Bunol C, Liu Y, Chen CS, Klag MJ, Whelton PK, He J. Effects of low-carbohydrate and low-fat diets: a randomized trial. Ann Intern Med. 2014 Sep 2;161(5):309-18. doi: 10.7326/M14-0180. |
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| ID | Title | Description |
|---|---|---|
| FG000 | Low Carbohydrate Diet | low carbohydrate diet: <40 grams carbohydrate/day |
| FG001 | Low Fat Diet | low fat diet: <30% fat, <7% saturated fat |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
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| ID | Title | Description |
|---|---|---|
| BG000 | Low Carbohydrate Diet | low carbohydrate diet: <40 grams carbohydrate/day |
| BG001 | Low Fat Diet | low fat diet: <30% fat, <7% saturated fat |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Mean |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Predicted Mean Difference in Body Weight From Baseline, by Assigned Dietary Group | Predicted mean difference from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | kg | 12 months |
|
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Low Carbohydrate Diet | low carbohydrate diet: <40 grams carbohydrate/day |
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| Term | Organ System | Source Vocabulary | Assessment Type | Notes | Statistical Information |
|---|---|---|---|---|---|
| Constipation at 3 months | Gastrointestinal disorders |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Dr. Lydia Bazzano | Tulane University | 5049887323 | lbazzano@tulane.edu |
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| ID | Term |
|---|---|
| D009765 | Obesity |
| D002318 | Cardiovascular Diseases |
| ID | Term |
|---|---|
| D050177 | Overweight |
| D044343 | Overnutrition |
| D009748 | Nutrition Disorders |
| D009750 | Nutritional and Metabolic Diseases |
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| ID | Term |
|---|---|
| D050528 | Diet, Carbohydrate-Restricted |
| D018752 | Diet, Fat-Restricted |
| ID | Term |
|---|---|
| D004035 | Diet Therapy |
| D044623 | Nutrition Therapy |
| D013812 | Therapeutics |
| D004032 | Diet |
| D009747 |
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| Behavioral |
<30% fat, <7% saturated fat |
|
Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values.
| 12 months |
| Predicted Mean Differences in HDL Cholesterol From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Total-HDL Cholesterol Ratio From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Triglycerides From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Systolic Blood Pressure From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Difference in Diastolic Blood Pressure, by Assigned Dietary Group | Mean Difference in Diastolic Blood Pressure predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values | 12 Months |
| Predicted Mean Difference in Plasma Glucose Level, by Assigned Dietary Group | Mean Difference in Plasma Glucose Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in Serum Insulin Level From Baseline, by Assigned Dietary Group | Mean Difference in Serum Insulin Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 months |
| Predicted Mean Differences in C-reactive Protein Level From Baseline, by Assigned Dietary Group | Mean Difference in C-reactive Protein Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values | 12 Months |
| Predicted Mean Differences in Serum Creatinine Level From Baseline, by Assigned Dietary Group | Mean Difference in Serum Creatinine Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 Months |
| Predicted Mean Differences of 10-y Framingham Risk Score From Baseline, by Assigned Dietary Group | Mean Difference in 10-y Framingham Risk Score predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | 12 Months |
| BG002 | Total | Total of all reporting groups |
| years |
|
| Sex: Female, Male | Count of Participants | Participants |
|
| Race/Ethnicity, Customized | Count of Participants | Participants |
|
| body weight | Mean | Standard Deviation | kg |
|
| body composition | Mean | Standard Deviation | % |
|
| body mass index | Mean | Standard Deviation | kg/m**2 |
|
| waist circumference | Mean | Standard Deviation | cm |
|
| systolic blood pressure | Mean | Standard Deviation | mm Hg |
|
| diastolic blood pressure | Mean | Standard Deviation | mm Hg |
|
| total cholesterol | Mean | Standard Deviation | mg/dL |
|
| LDL cholesterol | Mean | Standard Deviation | mg/dL |
|
| HDL cholesterol | Mean | Standard Deviation | mg/dL |
|
| total-HDL cholesterol ratio | Mean | Standard Deviation | unitless |
|
| triglycerides | Mean | Standard Deviation | mg/dL |
|
| plasma glucose | Mean | Standard Deviation | mg/dL |
|
| serum insulin | Mean | Standard Deviation | pmol/L |
|
| serum creatinine | Mean | Standard Deviation | mg/dL |
|
| C-reactive protein | Mean | Standard Deviation | nmol/L |
|
| Medication use | Count of Participants | Participants |
|
| Physical activity level | Mean | Standard Deviation | MET-h/wk |
|
| Framingham risk percent | The Framingham Risk score predicts the 10-year risk of developing coronary heart disease (CHD). Risk is predicted based on gender-specific tables provided by Wilson et al (Circulation 1998: 1837-47) comprised of the sum of points obtained from the following factors: age, presence of diabetes, cigarette smoking, blood pressure, high density lipoprotein level, and total cholesterol level. Risk calculated from this score can range from a 1% chance of developing CHD to a >= 56% chance of developing CHD in men --- and a 1% chance of developing CHD to a >=32% chance of developing CHD in women. | Mean | Standard Deviation | % |
|
| Units | Counts |
|---|
| Participants |
|
|
| Primary | Predicted Mean Differences in Lean Mass From Baseline, by Assigned Dietary Group | Mean Difference in Lean Mass predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | % of body weight that is lean mass | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Fat Mass From Baseline, by Assigned Dietary Group | Mean Difference in Fat Mass predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | % body weight that is fat mass | 12 months |
|
|
|
| Primary | Predicted Mean Differences of Waist Circumference From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | cm | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Total Cholesterol Level From Baseline by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mmol/L | 12 months |
|
|
|
| Primary | Predicted Mean Differences in LDL Cholesterol Level From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mmol/L | 12 months |
|
|
|
| Primary | Predicted Mean Differences in HDL Cholesterol From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mmol/L | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Total-HDL Cholesterol Ratio From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | ratio | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Triglycerides From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mmol/L | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Systolic Blood Pressure From Baseline, by Assigned Dietary Group | Predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mm Hg | 12 months |
|
|
|
| Primary | Predicted Mean Difference in Diastolic Blood Pressure, by Assigned Dietary Group | Mean Difference in Diastolic Blood Pressure predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values | Posted | Mean | 95% Confidence Interval | mm Hg | 12 Months |
|
|
|
| Primary | Predicted Mean Difference in Plasma Glucose Level, by Assigned Dietary Group | Mean Difference in Plasma Glucose Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | mmol/L|| | 12 months |
|
|
|
| Primary | Predicted Mean Differences in Serum Insulin Level From Baseline, by Assigned Dietary Group | Mean Difference in Serum Insulin Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | pmol/L | 12 months |
|
|
|
| Primary | Predicted Mean Differences in C-reactive Protein Level From Baseline, by Assigned Dietary Group | Mean Difference in C-reactive Protein Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values | Posted | Mean | 95% Confidence Interval | nmol/L | 12 Months |
|
|
|
| Primary | Predicted Mean Differences in Serum Creatinine Level From Baseline, by Assigned Dietary Group | Mean Difference in Serum Creatinine Level predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | µmol/L¶ | 12 Months |
|
|
|
| Primary | Predicted Mean Differences of 10-y Framingham Risk Score From Baseline, by Assigned Dietary Group | Mean Difference in 10-y Framingham Risk Score predicted from random-effects models that included diet, time, and diet-by-time interaction term. Markov-chain Monte Carlo techniques were used to impute missing values. | Posted | Mean | 95% Confidence Interval | % risk of developing CVD in next 10 yrs | 12 Months |
|
|
|
| 0 |
| 75 |
| 19 |
| 75 |
| EG001 | Low Fat Diet | low fat diet: <30% fat, <7% saturated fat | 0 | 73 | 23 | 73 |
| Constipation at 6 months | Gastrointestinal disorders |
|
| Constipation at 12 months | Gastrointestinal disorders |
|
| Fatigue at 3 months | General disorders |
|
| Fatigue at 6 months | General disorders |
|
| Fatigue at 12 months | General disorders |
|
| Headache at 3 months | General disorders |
|
| Headache at 6 months | General disorders |
|
| Headache at 12 months | General disorders |
|
| Thirst at 3 months | General disorders |
|
| Thirst at 6 months | General disorders |
|
| Thirst at 12 months | General disorders |
|
| Polyuria at 3 months | General disorders |
|
| Polyuria at 6 months | General disorders |
|
| Polyuria at 12 months | General disorders |
|
| Diarrhea at 3 months | Gastrointestinal disorders |
|
| Diarrhea at 6 months | Gastrointestinal disorders |
|
| Diarrhea at 12 months | Gastrointestinal disorders |
|
| Heartburn at 3 months | Gastrointestinal disorders |
|
| Heartburn at 6 months | Gastrointestinal disorders |
|
| Heartburn at 12 months | Gastrointestinal disorders |
|
| Gas at 3 months | Gastrointestinal disorders |
|
| Gas at 6 months | Gastrointestinal disorders |
|
| Gas at 12 months | Gastrointestinal disorders |
|
| Nausea at 3 months | General disorders |
|
| Nausea at 6 months | General disorders |
|
| Nausea at 12 months | General disorders |
|
| Vomiting at 3 months | Gastrointestinal disorders |
|
| Vomiting at 6 months | Gastrointestinal disorders |
|
| Vomiting at 12 months | Gastrointestinal disorders |
|
| Decreased appetite | General disorders |
|
| Decreased appetite | General disorders |
|
| Decreased appetite | General disorders |
|
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| D001835 |
| Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| Nutritional Physiological Phenomena |
| D000066888 | Diet, Food, and Nutrition |
| D010829 | Physiological Phenomena |
| Change of % lean mass after 12 months |
|
| Change of % fat mass after 12 months |
|
| Change in waist circumference after 12 mo |
|
| Change of total cholesterol after 12 mo |
|
| Change in LDL cholesterol level after 12 mo |
|
| Change in HDL cholesterol level after 12 mo |
|
| Change in Total-HDL cholesterol level after 12 mo |
|
| Change in Triglycerides after 12 mo |
|
| Change in Systolic Blood Pressure after 12 mo |
|
| Change in Diastolic Blood Pressure after 12 mo |
|
| Change in Plasma Glucose Level after 12 months |
|
| Change in Serum Insulin Level after 12 mo |
|
| Change in Serum Creatinine Level after 12 mo |
|
| hange in Serum Creatinine Level after 12 mo |
|
| Change in 10-Y Framingham Risk Score after 12 mo |
|