Study of the Effect of a Very-Low-Carbohydrate Diet on Energy Expenditure
| Status: | Completed |
|---|---|
| Conditions: | Food Studies, Obesity Weight Loss |
| Therapuetic Areas: | Endocrinology, Pharmacology / Toxicology |
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 8/11/2018 |
| Start Date: | October 22, 2013 |
| End Date: | February 23, 2015 |
Effect of a Eucaloric Ketogenic Diet on Energy Expenditure: A Pilot Study
Background:
- Popular weight loss plans often restrict carbohydrates or fat. Research shows that
very-low-carbohydrate (ketogenic) diets lead to greater weight loss than low-fat diets.
Researchers want to know if eating fewer carbohydrates changes the number of calories the
body uses. They also want to know how a ketogenic diet affects hunger, hormones, and food
preferences.
Objectives:
- To better understand how the body responds to different diets.
Eligibility:
- Men 18 to 50 years old who are healthy but overweight.
Design:
- Participants will have 3 screening visits:
1. Medical history, physical exam, blood test, and EKG. They will eat during the
visit.
2. For the week before the visit, participants will wear physical activity monitors
daily. They will record everything they eat and sample the special diet. At the
visit, they will receive an EKG and heart rate test while biking for 30 minutes.
3. For the week before the visit, participants will wear the physical activity
monitors. They will eat all their meals from the special diet that will be
provided. At the visit, they will answer questions and bike for 60 minutes.
- After screening, for 1 week, participants will visit the clinic daily to receive that
day s food. They will not eat or drink anything else except water.
- Then participants will stay at the clinic for 8 weeks. They cannot leave but can have
visitors. Participants will wear physical activity monitors, bike daily, and follow
different diets. Tests will be given daily, and may include weighing, X-rays, and blood
and urine tests. They will spend several days in a monitored room to test oxygen and
carbon dioxide.
- Popular weight loss plans often restrict carbohydrates or fat. Research shows that
very-low-carbohydrate (ketogenic) diets lead to greater weight loss than low-fat diets.
Researchers want to know if eating fewer carbohydrates changes the number of calories the
body uses. They also want to know how a ketogenic diet affects hunger, hormones, and food
preferences.
Objectives:
- To better understand how the body responds to different diets.
Eligibility:
- Men 18 to 50 years old who are healthy but overweight.
Design:
- Participants will have 3 screening visits:
1. Medical history, physical exam, blood test, and EKG. They will eat during the
visit.
2. For the week before the visit, participants will wear physical activity monitors
daily. They will record everything they eat and sample the special diet. At the
visit, they will receive an EKG and heart rate test while biking for 30 minutes.
3. For the week before the visit, participants will wear the physical activity
monitors. They will eat all their meals from the special diet that will be
provided. At the visit, they will answer questions and bike for 60 minutes.
- After screening, for 1 week, participants will visit the clinic daily to receive that
day s food. They will not eat or drink anything else except water.
- Then participants will stay at the clinic for 8 weeks. They cannot leave but can have
visitors. Participants will wear physical activity monitors, bike daily, and follow
different diets. Tests will be given daily, and may include weighing, X-rays, and blood
and urine tests. They will spend several days in a monitored room to test oxygen and
carbon dioxide.
Popular weight loss strategies often prescribe targeted reduction of dietary carbohydrate or
fat. Recent clinical trials in obese subjects have found that low-carbohydrate diets result
in greater weight loss compared with low-fat diets on a time scale of months when diet
adherence was likely the highest. One hypothesis regarding the mechanism of improved weight
loss with low carbohydrate diets is that such diets significantly modify the body s hormonal
milieu to influence metabolic regulation and energy expenditure. Low-carbohydrate diets may
thereby offer a metabolic advantage over low fat diets. In addition, low-carbohydrate diets
may also decrease hunger or increase satiety compared to low-fat diets.
Determining the mechanism whereby one diet leads to greater weight loss than another is
hampered by the inability to accurately measure food intake or physical activity in an
outpatient setting. Thus, an inpatient feeding study lasting many weeks is required to
accurately measure energy balance differences between isocaloric diets that differ in
macronutrient composition. In this pilot multicenter cross-over study in 16 overweight and
class I obese men, we will measure changes in energy expenditure in response to 4 weeks of
inpatient feeding of a eucaloric, very low carbohydrate, ketogenic diet (5% Carbohydrate, 15%
Protein, 80% Fat) immediately following an inpatient period of at least 4 weeks of consuming
an energy balanced standard American diet (50% Carbohydrate, 15 % Protein, 35% Fat).
fat. Recent clinical trials in obese subjects have found that low-carbohydrate diets result
in greater weight loss compared with low-fat diets on a time scale of months when diet
adherence was likely the highest. One hypothesis regarding the mechanism of improved weight
loss with low carbohydrate diets is that such diets significantly modify the body s hormonal
milieu to influence metabolic regulation and energy expenditure. Low-carbohydrate diets may
thereby offer a metabolic advantage over low fat diets. In addition, low-carbohydrate diets
may also decrease hunger or increase satiety compared to low-fat diets.
Determining the mechanism whereby one diet leads to greater weight loss than another is
hampered by the inability to accurately measure food intake or physical activity in an
outpatient setting. Thus, an inpatient feeding study lasting many weeks is required to
accurately measure energy balance differences between isocaloric diets that differ in
macronutrient composition. In this pilot multicenter cross-over study in 16 overweight and
class I obese men, we will measure changes in energy expenditure in response to 4 weeks of
inpatient feeding of a eucaloric, very low carbohydrate, ketogenic diet (5% Carbohydrate, 15%
Protein, 80% Fat) immediately following an inpatient period of at least 4 weeks of consuming
an energy balanced standard American diet (50% Carbohydrate, 15 % Protein, 35% Fat).
- INCLUSION CRITERIA:
- Age 18-50 years, male
- Weight stable (< 5 % over past 6 months)
- Current stable weight no more than 8% below lifetime maximum weight
- Body mass index (BMI) greater than or equal to 25 kg/m(2) but less than 35 kg/m(2),
with each study site recruiting an equal number of subjects from the overweight range
of 25 kg/m(2) less than or equal to BMI < 30 kg/m(2) and from the class I obese range
of 30 kg/m(2) less than or equal to BMI < 35 kg/m(2)
- Otherwise healthy, as determined by medical history and laboratory tests
- Able to complete daily bouts of stationary cycling at a moderate rate and intensity
- Written informed consent
- Willing to eat all the food provided in the study
- Willing to continue consistently their habitual caffeine intake
EXCLUSION CRITERIA:
- BMI < 25 kg/m(2) or greater than or equal to 35 kg/m(2)
- Blood pressure > 140/90 mm Hg
- Evidence of metabolic or cardiovascular disease, or disease that may influence
metabolism (e.g. cancer, diabetes, thyroid disease)
- Taking any prescription medication or other drug that may influence metabolism (e.g.
diet/weight-loss medication, asthma medication, blood pressure medication, psychiatric
medications, corticosteroids, or other medications at the discretion of the PI and/or
study team)
- Hematocrit < 40%
- Participating in a regular exercise program (> 2h/week of vigorous activity)
- Dietary carbohydrate less than 30% or greater than 65% of total calories as determined
by food frequency questionnaire
- Caffeine consumption > 300 mg/day
- Regular use of alcohol (> 2 drinks per day), tobacco (smoking or chewing)
amphetamines, cocaine, heroin, or marijuana over past 6 months
- Past or present history of eating disorder (including binge eating) or psychiatric
disease, including claustrophobia since part of the protocol will involve being
confined to a small room for whole-body indirect calorimetry
- Volunteers with strict dietary concerns (e.g. vegetarian or kosher diet, multiple food
allergies)
- Volunteers unwilling or unable to give informed consent
We found this trial at
1
site
9000 Rockville Pike
Bethesda, Maryland 20892
Bethesda, Maryland 20892
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