NUTRITION AND OBESITY--PHYSIOLOGICAL MECHANISMS

Project: Research project

Project Details

Description

It is critical to identify and characterize factors involved in obesity,
so that interventions to prevent or reverse the nutrition-related negative
health sequelae of obesity can be developed. To do so requires a better
understanding of lean-obese differences in the mechanisms that determine
human food intake. The proposed studies represent the first systematic
investigation of three important factors involved in the regulation of
energy and macronutrient intake in obese and lean females and males. These
are: l) the energy content of ingested foods; 2) the volume or weight of
ingested foods; and 3) the macronutrient composition of ingested foods.
Our approach is to use rigorous laboratory-based procedures to isolate and
define variables that affect human caloric and macronutrient intake, and
the proposed experiments logically follow from previous work this
laboratory has performed examining the determinants of human food intake.
These studies will take advantage of new food technologies that have
allowed the development of preload meals that can be consumed orally or
infused intragastrically, yet do not differ detectably in their sensory
properties. The use of intragastric infusions of the same foods that are
consumed orally provides a unique tool for dissociating orosensory and
cognitive controls (which are important cues particularly for obese
individuals) from postingestive physiological controls of energy and
macronutrient intake. A dose-response preloading paradigm provides the
most sensitive index of satiety, and the three studies in this proposal
reflect this design, Specifically, we will test the hypothesis that
thresholds relating to energy or volume detection are elevated or absent
in obese individuals. We will also test the hypothesis that calorie-for-
calorie, energy provided by fat (as compared to carbohydrate) will be less
satiating in obese individuals. In all studies we will be comparing the
responses of obese and lean individuals to test the predictions that
obesity is associated with: I) an impaired regulation of energy intake; 2)
a relative insensitivity to energy provided by fat as compared to
carbohydrate; and 3) a greater reliance on orosensory/cognitive cues as
compared to postingestive influences. Studies like these performed in
animals have generated important insights into the contributions of
orosensory, gastric, and postgastric stimulation in determining eating
behavior, although comparable systematic research has not been conducted
in humans, The proposed experiments will provide crucial new information
on the respective roles of energy content, the volume or weights of foods,
macronutrient composition, and interactions between orosensory and
postingestive factors in the regulation of energy and macronutrient
intake. This information will be important in forming the foundation for
more mechanistic analyses to follow and for the eventual development of
interventions to prevent or reverse obesity-related illness.
StatusFinished
Effective start/end date9/1/958/31/01

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