Measuring Free-living Energy Expenditure Using Direct Calorimetry
| Status: | Completed |
|---|---|
| Conditions: | Obesity Weight Loss |
| Therapuetic Areas: | Endocrinology |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 4/21/2016 |
| Start Date: | January 2012 |
| End Date: | January 2016 |
Although instruments such as pedometers and heart rate monitors are helpful for those who
use exercise to maintain their weight, they do not actually measure calories expended, which
is a critical piece of information necessary for sustained weight management. The purpose of
this study is to determine the accuracy of a new device that measures calories burned based
upon heat produced by the body. Since heat production is directly proportional to calories
burned, this device has the potential to accurately measure energy expended in many
different settings.
use exercise to maintain their weight, they do not actually measure calories expended, which
is a critical piece of information necessary for sustained weight management. The purpose of
this study is to determine the accuracy of a new device that measures calories burned based
upon heat produced by the body. Since heat production is directly proportional to calories
burned, this device has the potential to accurately measure energy expended in many
different settings.
Current approaches to measuring total daily energy expenditure (TDEE) in free-living
individuals are limited by cost, accuracy, and lack of sensitivity to specific activities.
Accurate, reliable, and low cost approaches for measuring TDEE are needed not only to
improve clinical outcomes (e.g. weight management), but also to meet public health research
objectives. In humans, EE is proportional to total heat loss, which is the sum of
conductive, convective, radiant and evaporative heat flows, and measurement of heat loss is
the basis of direct calorimetry. However, it has not been possible to accurately measure all
forms of heat flux in free-living humans, particularly evaporative heat loss, which can be a
substantial component of total heat production. A recently developed heat flow gauge with
the capacity to measure all forms of heat flux has shown promise in proof of concept trials
and pilot studies, but its accuracy in measuring TDEE has not yet been thoroughly tested.
Moreover, how accuracy is affected by factors such as clothing, ambient temperature, and
adiposity has not been studied. The objectives of the proposed research are to a) refine the
measurement of TDEE based on total heat flux by determining how factors such as clothing,
ambient temperature, age, sex, and body composition influence accuracy; b) compare the
accuracy of this approach against the criterion measurements of Doubly Labeled Water (DLW)
and whole-room indirect calorimetry; and c) compare the accuracy against a similar
instrument that measures heat flux, but is not capable of directly measuring the evaporative
component. The proposed research is innovative because it will test the accuracy of an
approach that is based on a physiological signal (heat production) which is directly
proportional to EE. In addition to accurately measuring TDEE, identifying and distinguishing
different types of physical activity is an important goal of physical activity related
research, but the capacity to do so is limited. Thus, an additional goal of the proposed
research is to determine if measurement of changes in heat flux can be used to identify EE
in specific bouts of activity and to differentiate between upper body and lower body
activity. The proposed studies will permit refinement of a technology that will have major
impact in both clinical practice and research. This new approach will potentially provide
substantive improvements in the measurement of TDEE in free-living humans and in the
assessment of physical activity and the associated energy cost.
individuals are limited by cost, accuracy, and lack of sensitivity to specific activities.
Accurate, reliable, and low cost approaches for measuring TDEE are needed not only to
improve clinical outcomes (e.g. weight management), but also to meet public health research
objectives. In humans, EE is proportional to total heat loss, which is the sum of
conductive, convective, radiant and evaporative heat flows, and measurement of heat loss is
the basis of direct calorimetry. However, it has not been possible to accurately measure all
forms of heat flux in free-living humans, particularly evaporative heat loss, which can be a
substantial component of total heat production. A recently developed heat flow gauge with
the capacity to measure all forms of heat flux has shown promise in proof of concept trials
and pilot studies, but its accuracy in measuring TDEE has not yet been thoroughly tested.
Moreover, how accuracy is affected by factors such as clothing, ambient temperature, and
adiposity has not been studied. The objectives of the proposed research are to a) refine the
measurement of TDEE based on total heat flux by determining how factors such as clothing,
ambient temperature, age, sex, and body composition influence accuracy; b) compare the
accuracy of this approach against the criterion measurements of Doubly Labeled Water (DLW)
and whole-room indirect calorimetry; and c) compare the accuracy against a similar
instrument that measures heat flux, but is not capable of directly measuring the evaporative
component. The proposed research is innovative because it will test the accuracy of an
approach that is based on a physiological signal (heat production) which is directly
proportional to EE. In addition to accurately measuring TDEE, identifying and distinguishing
different types of physical activity is an important goal of physical activity related
research, but the capacity to do so is limited. Thus, an additional goal of the proposed
research is to determine if measurement of changes in heat flux can be used to identify EE
in specific bouts of activity and to differentiate between upper body and lower body
activity. The proposed studies will permit refinement of a technology that will have major
impact in both clinical practice and research. This new approach will potentially provide
substantive improvements in the measurement of TDEE in free-living humans and in the
assessment of physical activity and the associated energy cost.
These studies will be conducted in Denver. CO. Eligible participants will be those local
to the University.
Study #1 (Effects of clothing and temperature)
Inclusion Criteria
- Body mass index (BMI) 19-25 kg/m2
- Age 18-45 years
Exclusion criteria
- Self-reported acute or chronic disease (e.g. diabetes, heart disease, thyroid
disease)
- Tobacco use (cigarettes, cigars, or chewing tobacco) within the past 6 months
- Females who are or who were recently (past year) pregnant or lactating.
- Resting diastolic blood pressure > 100 mm HG or resting systolic blood pressure > 160
mm HG
- Contra-indications to exercise (e.g. orthopedic limitations)
Study #2 (Effect of age, sex, and adiposity)
Inclusion Criteria • Age ≥18 yrs
Exclusion criteria
- Weight > 300 lbs (due to DXA limitations)
- Self-reported acute or chronic disease (diabetes, heart disease, thyroid disease)
- Tobacco use (cigarettes, cigars, or chewing tobacco) within the past 6 months
- Females who are or who were recently (past year) pregnant or lactating.
- Resting diastolic blood pressure > 100 mm HG or resting systolic blood pressure > 160
mm HG
- Contra-indications to exercise (e.g. orthopedic limitations)
Study #3 (Doubly labeled water)
Inclusion Criteria
• Age ≥18 yrs
Exclusion criteria
- Weight > 300 lbs (due to DXA limitations)
- Self-reported acute or chronic disease (diabetes, heart disease, thyroid disease)
- Tobacco use (cigarettes, cigars, or chewing tobacco) within the past 6 months
- Females who are or who were recently (past year) pregnant or lactating
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