Effects of a low-insulin-response, energy-restricted diet on weight loss and endocrinological parameter in obese, anovulatory women in their reproductive years
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Date
2002-12
Authors
Lusardi, Liz-Mare
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
There is consistent evidence that obese women are less fertile than women of normal
body weight. Obesity, in particular android obesity, is associated with several sex
steroid abnormalities in premenopausal women including: increased free estrogen
and androgen fractions, reduced sex hormone-binding globulin and increased bioactive
estrogen delivery to target tissue.
The state of insulin resistance with secondary hyperinsulinemia is commonly
observed in obese, infertile women whereas the gonadotrophic effects of insulin on
ovarian steroid hormone synthesis have been indicated in vivo and in vitro. Insulin can
directly and indirectly stimulate ovarian androgen production. The exaggerated
insulin action on ovarian tissues may present the pathological mechanism for
disturbances in the endocrine profile and menstrual cycle and infertility in some obese
women.
Due to certain limitations we did not diagnose anovulation whereas only a certain
percentage of the subjects in each group were hyperinsulinemic. One of the problems
experienced was the drop outs in each group.
Weight loss is associated with a significant improvement in menstrual abnormalities,
ovulation and fertility rates with a reduction in hyperandrogenism and
hyperinsulinemia. It is suggested that weight loss should be the first option in the
treatment of overweight infertile women. Intervention studies suggest that reducing
weight and/or hyperinsulinemia either by diet alone or a combination of diet and drug
therapy should be investigated.
This study was undertaken to evaluate the effects of a low-insulin-response, energyrestricted
diet (LID) on anthropometric and endocrinological parameters in obese
women with menstrual abnormalities. For the purpose of this study we compared the
effects LID to a normal balanced-energy restricted diet. The principles for the LID
were based on the available literature regarding the insulin response to foods and their
combinat ions. At baseline 37 candidates were randomly assigned into two groups. Group A followed
the LID and consisted of 19 candidates whereas Group B followed the NO and
consisted of 18 subjects. The inclusion criteria were: obese (BMI > 30kg/m2),
premonopausal, insulin resistance, anovulation and between the ages of 18 and 04
years of age whereas the exclusion criteria included increased fasting and stimulated
glucose concentrations, cigarette-smokers, and the presence of any chronic medical
condition. Subject fasted for a 10 to 12 hour period after following a 250 g
carbohydrate diet for three-days prior to baseline blood sampling. Blood samples were
collected at baseline and at the end of the 16-week trial and analyzed for fasting
insulin and glucose, testosterone (T), luteinizing hormone (LH), follicle stimulating
hormone (FSH), estrogen (E), prolactin, thyroid stimulating hormone (TSH),
thyroxine (FT4), leptin and progesterone. Insulin resistance were defined as a
glucose-to-insulin ratio < 4.5. Stimulated 30 and 120-minute insulin and glucose were
collected after subjects consumed 82.5g of monohydrate glucose powder diluted in
300ml water. Due to certain limitations we did not diagnose anovulation whereas only a certain
percentage of the subjects in each group were hyperinsulinemic. One of the problems
experienced was the drop outs in each group. Results form this trial indicated a significant reduction in fasting and JO-minute
stimulated insulin, LH, and testosterone and leptin concentrations in the NO group
whereas only leptin concentrations reduced significantly in the LID group. A
significant reduction occurred in mean weight, BMI, body fat percentage, waist and
hip circumference in both groups. Numerous studies evaluated the effects of weight loss on fertility but to our
knowledge this is the first trial of its kind to evaluate the effects of two different test
diets on fertility parameters. Results from this trial confirm the positive effects of
weight loss on endocrinological and anthropometric parameters in obese women,
however, the LID showed no beneficial effects over the NO. Future research is
needed to evaluate the effect of diet manipulation on fertility parameters with specific
regard to diet manipulation in combination with drug therapy. This trial, however,
serves as a good pilot study for future research of this kind.
Description
Keywords
Obesity -- Treatment, Weight loss, Infertility, Dissertation (M. Nutrition (Dietetics))--University of the Free State, 2002