| Summary: | The controversial condition of carbohydrate craving is believed by some
researchers to be a defect in the regulation of food intake by an individual.
This defect is believed to be responsible for the inability of some persons to
control their food intake and therefore their weight. Research was conducted
to test the hypothesis that, given a group of carbohydrate cravers and a group
of noncravers, the cravers will experience a greater plasma insulin response
(concentration and area under the curve) than will the noncravers, and that,
because of this higher response, the cravers will experience equal or lower
plasma glucose levels during a carbohydrate load. A second hypothesis was
that, because of cephalic insulin response due to sensory stimuli, cookies would
elicit a greater plasma insulin response than would a glucose solution. This
higher plasma insulin response may in part explain the uncontrollable snacking
that some individuals experience. The purpose of this research was to attempt
to identify a biochemical distinction between persons who crave carbohydrates
and persons who do not crave carbohydrates. Eleven overweight female
subjects, age 30 to 40, were recruited and divided into two groups, five
carbohydrate cravers and six noncravers, based on scores received on a
questionnaire that was devised for this study to attempt to distinguish between
the groups. A Restrained Eating questionnaire was also administered to the
subjects. Both groups had similar, but high, restrained eating scores, indicating
that all of the subjects were probably restrained eaters. The eating restraint, as
supported by the reported frequency of dieting among the subjects, may well
have influenced the subjects' responses to the carbohydrate craving
questionnaire.
Utilizing these two groups of subjects, two tests were administered. The oral
glucose tolerance test was administered, utilizing 75 g of carbohydrate each in
the forms of glucose solution and cookies, which were administered in a
random order. The tests were administered during the premenstrual phase of
the subjects' menstrual cycles, 0-10 days prior to the onset of menstruation.
Blood was drawn and assayed for plasma glucose and insulin.
The research showed that the cravers experienced a significantly greater plasma
insulin concentration and area under the curve than the noncravers, particularly
at the 30, 60 and 120 minute time points with the glucose treatment. For the
glucose treatment, the cravers experienced plasma insulin concentrations that
were 32% to 50% greater than those of the noncravers in the early portion of
the test. This supports the hypothesis which states that cravers will experience
a greater plasma insulin response to a carbohydrate load than will noncravers.
This elevated plasma insulin level may be responsible for the carbohydrate
cravings that the individuals experience. There was no significant difference in
plasma glucose levels at any time point in either of the tests as compared
between the cravers and noncravers, thus supporting the expectation that these
levels would be similar between the groups. The hypothesis that cookies would elicit a greater plasma insulin response than would a glucose solution was not
supported. Any cephalic insulin response which may have resulted from the
sight and smell of the cookies, while not specifically measured, was not strong
enough to override the physiological factors that control insulin release.
Therefore, the glucose solution elicited a significantly greater plasma insulin
concentration than did the cookies in the cravers during the first two hours of
the tests, and a significantly greater area under the curve for the cravers at 60
minutes and both groups at 120 minutes. However, the cookies did have an
effect on insulin release at the fasting point, causing elevated (x = 79%) plasma
insulin levels in three of five subjects who were waiting while others were eating
the cookies, as compared with these subjects' fasting insulin levels when they
were not exposed to the cookies prior to their glucose test. Another finding
was a difference between the groups in fasting plasma insulin concentrations
over the 10 day premenstrual portion of their menstrual cycles. The noncravers
experienced fasting plasma insulin concentrations that decreased as the onset of
menstruation was approached, which would parallel the decrease in
progesterone levels. However, the cravers experienced first a decrease in
fasting plasma insulin levels to day 3 premenstrual, and then an increase to the
level of that found 8-10 day premenstrual. This pattern is contrary to what
would be expected as progesterone levels drop, and suggests an altered pattern
of progesterone levels in the cravers, although progesterone was not measured
in this study.
To summarize, in a group of overweight women, carbohydrate cravers and non
cravers, the cravers experienced a greater plasma insulin response than did the
noncravers for the glucose treatment but not for the cookie treatment, and
there was no significant difference between the groups for plasma glucose
concentration for either treatment. === Graduation date: 1991
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