Study of Macronutrients and Heart Disease Risk
| Status: | Completed |
|---|---|
| Conditions: | High Blood Pressure (Hypertension), Obesity Weight Loss, Peripheral Vascular Disease |
| Therapuetic Areas: | Cardiology / Vascular Diseases, Endocrinology |
| Healthy: | No |
| Age Range: | 22 - 75 |
| Updated: | 11/21/2018 |
| Start Date: | January 2008 |
| End Date: | January 2012 |
Macronutrient Composition of Diet and Risk Factors for Cardiovascular Disease
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.
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.
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.
Inclusion Criteria:
- Men or women aged 22 - 75 years, any race/ethnicity
- BMI of 30 - 45 k/m2
- Willing and able to provide informed consent
Exclusion Criteria:
- History of self-reported clinical CVD (angina/myocardial infarction, coronary
revascularization, heart failure, stroke/transient ischemic attack, peripheral
arterial disease)
- Medical condition in which a low-carbohydrate diet may not be advised (diabetes, renal
disease, cancer requiring treatment during the past year, osteoporosis, untreated
thyroid disease, gout)
- Current use of more than 2 antihypertensive or more than 2 cholesterol-lowering
medications
- For women, current pregnancy or breastfeeding or plans to become pregnant during the
study period
- Consumption of more than 21 alcoholic beverages per week
- Currently on a diet or using prescription weight loss medications, underwent weight
loss surgery, and/or experienced weight loss >15 pounds within 6 months of study entry
- Plans to move out of the study area (>1 hour from study site) or difficulty to come to
the study site
- Participation of another household member in the study; employees or persons living
with employees of the study
- Participation in other lifestyle intervention trials currently
- At the discretion of the study coordinator
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