| Research Article |
Open Access |
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| A Low Glycemic Index Diet Combined with an Aerobic-Resistance Exercise
Program Reduces Risk Factors Associated with the Metabolic Syndrome |
| Kendra E Brett1 and Kelly A Meckling2* |
| 1Department of Human Kinetics, University of Ottawa, Healthy Active Living and Obesity Research Group, Children’s Hospital of Eastern Ontario, Ottawa, ON, Canada |
| 2Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada |
| *Corresponding author: |
Kelly A Meckling
Department of Human Health and
Nutritional Sciences
University of Guelph, Guelph, ON, Canada, N1G2W1
Tel: 519-824-4120 ext: 53742
Fax: 519-763-5902
E-mail: kmecklin@uoguelph.ca |
|
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| Received June 27, 2012; Accepted August 04, 2012; Published August 09, 2012 |
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| Citation: Brett KE, Meckling KA (2012) A Low Glycemic Index Diet Combined
with an Aerobic-Resistance Exercise Program Reduces Risk Factors Associated
with the Metabolic Syndrome. J Obes Wt Loss Ther 2:142. doi:10.4172/2165-7904.1000142 |
| |
| Copyright: © 2012 Brett KE, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited. |
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| Abstract |
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| Background: The purpose of this study was to examine the effects of Low Glycemic Index (LGI) and High
Glycemic Index (HGI) versions of a low fat, Moderate Carbohydrate (CHO), moderate protein diet, when combined
with an exercise program, on Cardiovascular Disease (CVD) risk factors in people with Metabolic Syndrome (MetS). |
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| Methods: The four groups included ad libitum and 30% calorie restricted high and low GI diets. Twenty six
individuals completed the 12 week intervention. Data was collected prospectively at weekly counselling sessions. |
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| Results: Calorie restriction was similar between groups (p=0.543), and thus the groups were pooled, leaving only
the HGI and LGI groups. The LGI group significantly reduced the GI of their diet (10.5 GI units), significantly reduced
the number of subjects classified with MetS (8 people), and had significantly greater improvements in total body
weight (7.2 kg), BMI (2.0 kg/m2), percent body fat (3.3 %) and hip circumference (4.9 cm) compared to the HGI groups,
as well as additional improvements in waist circumference (6.3 cm), blood pressure (10.5 mmHg systolic, 5.5 mmHg
diastolic), triglycerides (0.6 mmol/L). Both groups had similar improvements in fitness. There were no significant
changes in fasting levels of blood glucose, serum insulin, and serum total, HDL, or LDL cholesterol. |
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| Conclusions: The LGI diet and exercise program had a greater ability to reduce the number and severity of CVD
risk factors in individuals with MetS, and represents valuable knowledge from which future lifestyle interventions can
be developed to reduce the incidence of MetS and the development of CVD. |
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| Keywords |
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| Metabolic syndrome; Low glycemic index; Obesity;
Cardiovascular disease |
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| Introduction |
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| Metabolic Syndrome (MetS) is a cluster of metabolic factors that
increase Cardiovascular Disease (CVD) and includes abdominal obesity,
hypertension, dyslipidemia and impaired fasting glucose [1]. The
current definition of MetS was established in 2005 by the International
Diabetes Federation (IDF), and is defined as having an elevated Waist
Circumference (WC) with ethnic specific cutoffs (europids: ≥ 102 cm
in males, ≥ 88 cm in females), plus any two of the following: elevated
triglycerides (TG) (>1.7 mmol/L or undergoing treatment), reduced
HDL cholesterol (<1.03 mmol/L in males, <1.29 mmol/L in females, or
undergoing treatment), raised Blood Pressure (BP) (systolic BP ≥ 130
mmHg, diastolic BP ≥ 85 mmHg, or undergoing treatment), or raised
fasting plasma glucose (>5.6 mmol/L, or previously diagnosed Type 2
Diabetes (T2D)) [2]. The main goal in the management of MetS is to
reduce the development of CVD by reducing the number and severity
of risk factors. The consensus is that a modified lifestyle, including a
modified diet and an increase in physical activity, should be the first
line of treatment; however the optimal diet for disease prevention has
yet to be determined. Many dietary approaches have been successful
for weight loss, including low-fat diets [3-5], low carbohydrate (CHO)
diets [6-10], and high protein diets [11-14], however, these diets have
difficulty addressing the entire MetS profile. There has been limited
research on lifestyle interventions using subjects with MetS [15-17],
however these studies are too few in number and variety of design to
recommend one specific treatment. |
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| Previous work from our lab found that a reduced fat, moderate
protein, moderate CHO diet when combined with exercise was easy
to maintain and effective in reducing MetS risk factors in overweight
women, however it did not modify fasting glucose levels [18]. Low
Glycemic Index (LGI) diets can improve insulin sensitivity [19-21] and
reduce the risk of T2D [22]. Furthermore, LGI diets have high satiety
and may promote spontaneous energy restriction [19,23,24], as well as improve dyslipidemia [19,25-29], promote reductions in body fat mass
[30] and BMI [31], and reduce CVD risk [32-34]. The attractiveness
of the LGI approach and in particular the Glycemic Load (GL) is that
they consider both the quality and quantity of carbohydrates and the
potential for interaction between them and with other nutrient and
non-nutritive components of foods. The aim of the current study
was to address whether the combination of a LGI diet with a low
fat, moderate CHO, moderate protein diet, when combined with
exercise, could reduce CVD risk factors in people with MetS. The main
objectives were to determine if i) the GI would influence how the diet
impacts the MetS risk factors, and ii) if calorie restriction is necessary
in a LGI diet to reduce energy consumption and reduce disease risk.
This study examined the short-term effects of four low fat, moderate
CHO, moderate protein diets that differed in mean GI and calorie
restriction, combined with exercise in free living adults with MetS. It
was hypothesized that the calorie restricted LGI diet would be more
beneficial than the HGI or ad libitum versions of the diets. |
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| Methods |
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| Study design |
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| Subjects were recruited from the city of Guelph through advertisements in the newspaper and community. The study was
approved by the University of Guelph Research Ethics Board, and
all subjects gave informed written consent. Inclusion criteria were as
follows: 18-60 years of age, BMI ≥ 27 kg/m2, and meeting the 2005
IDF definition of MetS. Individuals were excluded if they were taking
any medications known to affect blood pressure, blood glucose, blood
lipids, or weight. While we recognized that a large proportion of the
population for whom this dietary strategy may be efficacious, may be on
these medications, we wanted to avoid the confounding of medication
use in this pilot study. Subjects who previously had stroke, myocardial
infarction or other major DVD events were also excluded. The
intervention consisted of a 12 week diet and exercise program. Subjects
were randomly assigned to one of four diets and all attended three
exercise sessions per week. Additional baseline measurements included
percent body fat, a 7 day food record and a fitness assessment. Daily
food records were kept throughout the intervention and periodically
7 day records were analyzed using The Food Processor for Windows
2000 (version 10.4 ESHA Research, Salem, Oregon). Subjects met once
a week with a study coordinator for individual nutrition counselling,
and were provided with additional resources such as menu plans, and
recipes. All baseline measurements were repeated at the end of the
intervention. Subjects did not receive any financial compensation, but
did receive a free membership to the University of Guelph Athletic
Center. |
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| Dietary component |
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| All subjects were instructed to consume a diet composed of 23%
protein, 30% fat, and 47% CHO, which describes a low fat, moderate
CHO diet that was previously shown to promote weight loss and
improve lipid profiles [18]. Subjects were randomized to one of four
experimental diets that differed in Glycemic Index (GI) and energy
restriction: 1) High Glycemic Index (HGI), ad libitum (HGI-AL); 2)
HGI with 30% Calorie Restriction (HGI-CR); 3) LGI, ad libitum (LGIAL)
and 4) LGI with 30% Calorie Restriction (LGI-CR). The HGI
subjects were instructed to consume as many HGI (GI>65) CHOs
as possible (i.e. whole wheat bread, English muffins, shredded wheat
cereal, baked potatoes, pineapple, and watermelon). The LGI subjects
were instructed to consume as many LGI (GI<50) CHOs as possible (i.e.
100% whole grain bread, unrefined cereals, sweet potatoes, legumes,
berries, and pears). The 30% calorie restriction was determined for
each individual based on the average caloric intake calculated from
the baseline 7 day food record. The ad libitum groups did not receive
counselling to encourage calorie restriction. |
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| Circuit training and fitness assessment |
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| Strength and cardiovascular fitness was assessed by a personal
trainer at the University of Guelph Athletic Center. For the chest and
leg press, subjects first completed 10 repetitions at a low level weight,
and then the load was increased to a sub-maximal weight. The number
of repetitions and load was recorded and the total weight lifted was
calculated. For abdominal strength, the subject completed a series of
curls and the distance traveled by their finger tips across the gym mat
was recorded, as was the number of curls and the time. The number
of curls completed per min was calculated. Cardiovascular fitness
was assessed using a sub-maximal cycling test. The difficulty level was
adjusted to reach 40% maximum Heart Rate (HR) for the 5 min warmup
and 65% maximum HR for the 10 min testing period. HR, difficulty
level and the revolutions per minute were recorded at 0, 2.5, 5, 7.5 and
10 min. At week 12, the difficulty level was adjusted to match baseline,
and the change in HR was calculated (final HR - baseline HR). |
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| Supervised fitness sessions were prescribed 3 days per week in the
morning and evenings. Sessions consisted of a warm-up on a stationary
bicycle (5 min), followed by a circuit with alternating resistance
machines and cardiovascular stations, which was completed twice
(1 min/station; 30 sec/station). Resistance machines included: chest
press, leg extension, leg curl, lateral pull-down, posterior deltoid fly,
seated row, leg press, and shoulder press. The aerobic stations included
exercises using a springboard pad or a step, and abdominal curls.
Completion of the circuit was followed by a series of stretches. |
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| Anthropometry and blood collection |
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| Height (cm) and weight (kg) were measured using a stadiometer
and digital scale, respectively. WC (cm) was measured using an inelastic
plastic measuring tape gently wrapped around the subject’s waist an
equal distance from the lowest rib and the top of the iliac crest. Hip
circumference (cm) was measured similarly around the subject’s hips
located at the top of the greater trochanter of each leg. Blood Pressure
(BP) was measured twice at each study visit using an automatic BP
monitor (Omron® IntelliSense™ BP monitor MODELHEM-907XL)
after a 5 min rest in the seated position and the measurements averaged.
Body composition was measure using Bioelectrical Impedance Analysis
(Bodystat® 1500) as we have previously described. |
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| Venous blood was collected after a 12 h fast and sent to a
commercial laboratory (LifeLabs, Kitchener, ON) for analysis of
glucose, TG, Total Cholesterol, HDL Cholesterol, and LDL Cholesterol.
Fasting serum insulin was analyzed in duplicate using a solid-phase
125I radioimmunoassay (Human Insulin Specific Radioimmunoassay,
Millipore, Missouri, United States; Precision: inter-assay 2.9-6.0%,
intra-assay 2.2-4.4%). |
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| Statistics |
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| An intention to treat “completers” analysis of the results was
performed [35], and included all subjects in the groups to which they
were assigned who completed all follow-up measures (n=26). The
rest of the subjects are reported as dropouts. All data are presented as
means ± Standard Error of the Mean (SEM). Initially, between group
comparisons were conducted using the baseline and week 12 data from
the four dietary groups (HGI-AL, HGI-CR, LGI-AL, and LGI-CR),
and statistical significance was assessed using a univariate ANOVA.
After finding no significant difference in the level of calorie restriction
between the four groups (data not shown; p=0.543), the groups were
pooled leaving only two groups that differed in mean GI (HGI and LGI).
Further statistical analysis was conducted using the pooled groups.
Between group comparisons were conducted using the baseline and
week 12 data, as well as the absolute change in the variables, and was
assessed for statistical significance using independent sample t-tests.
Within group differences between baseline and final measurements
were assessed using paired sample t-tests. The number of subjects
meeting each of the MetS criteria and the number classified with MetS
at baseline and after the intervention were compared using a Chi-
Square test. Differences were considered significant if p<0.05 (SPSS
version 17.0, SPSS Inc.). |
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| Results |
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| Subjects |
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| Forty-five individuals met the inclusion criteria and were
randomized to an intervention group. Seven subjects withdrew after
receiving their diet assignment but did not begin the intervention
(HGI-AL n=3; HGI-CR n=3; LGI-AL n=1). An additional 12 subjects withdrew before completing the study (HGI-AL n=3; HGI-CR n=3;
LGI-AL n=4; LGI-CR n=2). Twenty-six subjects completed the entire
study (HGI-AL n=6; HGI-CR n=5; LGI-AL n=6; LGI-CR n=9). |
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| Dietary measures |
|
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| All dietary groups appeared to restrict their calorie intake, regardless
of the dietary counselling advice given and there were no differences in
the level of calorie restriction between the four groups (data not shown;
p=0.543). There were significant differences in the average GI of the
high and low GI diets (data not shown; p<0.05), therefore the division
into ad libitum and calorie restricted groups was eliminated, leaving
two groups differing only in GI; HGI (n=11) and LGI (n=15) (Table 1). |
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Table 1: Dietary analysis of the baseline and study diets for the HGI and LGI groups, and the overall change in the dietary variables. |
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| Both groups had significant reductions from baseline in total
energy, CHO: protein ratio, Glycemic Load (GL)/day, total CHO,
total fat, and sodium (p<0.05). The LGI group also had significant
reductions from baseline in the percentage of calories from fat, the GI,
total protein, saturated fat, monounsaturated fat, polyunsaturated fat,
transfatty acids, omega-6 fatty acids, and caffeine (p<0.05). The HGI
group also had a significant reduction in dietary fibre (p<0.05). The GI
of the diet was significantly lower in the LGI group during the study
compared to the HGI group, and the overall change in the GI of the diet
was significantly larger in LGI group (p<0.05). |
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| Anthropometry and blood biochemistry |
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| Table 2 shows that both groups had significant reductions from
baseline in total body weight, BMI, WC, HC, SBP, DBP, and fasting
serum TG (p<0.05). Of these variables, the absolute change from
baseline in total body weight, BMI, and HC was significantly greater
in the LGI group (p<0.05). In addition, the LGI group also had a
significant reduction in percent body fat from baseline, and this change
was significantly larger than that of the HGI group (p<0.05). The HGI
group did have significant reductions from baseline in fasting serum
total and HDL cholesterol; however these changes did not differ from
the LGI group. |
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Table 2: Baseline, week 12 and the change in anthropometric measurements and blood biochemistry of the subjects who completed all 12 weeks of the study. |
|
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| Fitness assessment |
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| Compliance to the fitness program varied from 50 to 100%
attendance. The mean attendance of the LGI group (84%) was
significantly greater than the attendance of the HGI group (67%)
(p<0.01). Both groups had significant increase in strength from baseline
on the chest press, leg press and abdominal curl fitness tests (p<0.05),
and these changes were similar between the groups (Table 3). For the
aerobic cycling test, both groups had reductions in exercising HR at 7.5
min, and the LGI group had reductions at 5 and 10 min. The HR was
significantly lower in the LGI group than the HGI group only at 10 min
(p<0.05). There were no significant differences in the absolute changes
in HR between groups at any time point (p<0.05). |
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Table 3: Baseline, week 12 and the change in the total load lifted, the number of abdominal curls completed, and exercising heart rate for the subjects who completed
the fitness tests. |
|
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| Metabolic syndrome criteria |
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| At baseline, 100% of the subjects met the IDF definition for MetS.
There was a significant reduction in the number of subjects who met the
definition of MetS in the LGI group (p<0.01), with only 47% of the LGI
group still being diagnosed with MetS at the end of the intervention; in
contrast 73% of the HGI group still met the definition for MetS (Table
4). Additionally, in the LGI group, there was a significant reduction
from baseline in the number of subjects meeting the MetS cut off for
TG (p<0.02), while there was only a trend towards a reduction in the
number is subjects meeting the MetS cut off for TG in the HGI group
(p=0.056). |
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Table 4: The number of subjects who met each MetS criteria and who would have been classified with MetS at baseline and at the end of the intervention in the HGI
(n=11) and LGI (n=15) groups. |
|
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| Discussion |
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| The present study was designed to assess the efficacy of combining
a LGI diet with a low fat, moderate CHO, moderate protein diet
with regular exercise on risk factors in individuals with MetS. These
findings provide evidence that in adults with MetS, a hypocaloric lowfat,
moderate CHO, LGI diet combined with a resistance and aerobic
training program for 12 weeks can: 1) reduce the number of individuals
who meet the IDF definition of MetS; 2) reduce the severity and/or the
number of MetS risk factors for adiposity, hypertension, dyslipidemia
and insulin resistance; 3) improve fitness. The hypothesis was partially
supported; the LGI diet was more beneficial than the HGI diet at
improving MetS risk factors, however the hypothesis that a calorie
restricted LGI diet would be more beneficial than ad libitum version
of the diet was not investigated due to similarities in calorie intake and
pooling of the study groups. The LGI group had a greater reduction
in the number of subjects classified with MetS, and greater changes in total body weight, BMI, percent body fat and HC, with additional
improvements in WC, BP, TGs, and fitness. Furthermore, subjects
were more satisfied with the LGI diet, which suggests improved
compliance outside of the clinical setting and that this intervention
could be successful in treating individuals with MetS. |
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| Of the 38 subjects who began the intervention, only 26 successfully
completed the study, giving a retention rate of 68%. A high attrition
rate is not commonly found in the literature on high and low GI diets,
with reports of 80% and 90% subject retention in 12 and 3 month
studies, respectively [29,36]; however these studies did not include an
exercise component and required a smaller overall time commitment.
The subjects allocated to the HGI or the ad libitum diets expressed more
dissatisfaction with their diet assignment, which may have contributed
to the greater number of withdrawals from these groups. The relatively
small number of subjects completing the study is certainly a limitation
of the study and may have led to the lack of statistical significance for
several of the parameters. |
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| Despite only counselling two groups to reduce their energy
intake, there was no difference in the calorie restriction between the
original four groups. It is possible that some subjects in the calorie
restricted groups had difficulties reaching their calorie goals because
they were not satiated by their diet, particularly the HGI-CR group,
as the consumption of HGI meals can increase ratings of hunger and
voluntary food intake [23]. However, it was particularly surprising
that the HGI-AL and LGI-AL groups had similar levels of calorie
restriction, as this contradicts evidence that LGI ad libitum diets are more satiating and may cause spontaneous energy restriction [19,24].
This suggests that LGI foods will not always result in energy restriction
when a diet is consumed ad libitum over a longer time. It is also possible
that some subjects were purposely underreporting their calorie intake,
as underreporting of energy intake is often a problem in weight loss
interventions, and overweight women often underreport their energy
intake [37]. The failure of the HGI group to significantly increase their
mean GI over the course of the study is not uncommon in the literature
[31], and suggests that individuals at risk for disease are making fewer
healthy dietary choices to begin with, including the consumption of
HGI foods. |
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| Both groups were successful in reducing their total energy
intake, CHO to protein ratio, GL, total fat, total CHO and sodium
from baseline; however the LGI diet group had additional benefits,
including significant reductions in the percentage of calories from
fat, the GI, saturated fat, and transfatty acid. In addition, while both
groups reduced their CHO consumption, the LGI group did so without
altering their dietary fibre intake, while the HGI group had a significant
reduction of 6 g of dietary fibre per day. |
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| Both groups had significant reductions in total body weight, BMI,
WC and HC, however, the change from baseline in these improvements
(except WC) were significantly greater in the LGI group. In addition,
the LGI group had a significant reduction in percent body fat, which
was not experienced by the HGI group. Overall, this indicates that
assignment to the LGI diet was more successful in reducing body
weight and body fat compared to assignment to the HGI diet. There was discordance in the reported and expected weight losses in both
groups. The reported mean energy restriction in the HGI group of 474
kcal per day should have resulted in a minimum weight loss of 5.2 kg
mean weight loss over the 12 weeks. This is minimum, because one
would expect extra energy to have been expended during the exercise
periods, which would result in an even greater energy deficit. Instead
the HGI group lost an average of 3.3 kg suggesting that this group
was underreporting their calories. Underreporting of calories occurs
frequently in obese populations and is often given as the reason why
these subjects fail to lose weight despite a reported reduced calorie
intake [38]. In contrast, the LGI group lost more weight (7.16 kg) than
expected (5.94 kg) based on the mean energy restriction of 544 kcal per
day, which may have been due to increased energy expenditure from
their higher gym attendance, and possibly more accurate recording of
their energy intake. |
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| The reductions in SBP and DBP were similar between the groups,
indicating that both interventions were effective at reducing BP in
individuals with MetS. This suggests that the GI of the diet did not play
a significant role in altering BP, which is consistent with previous work
[28,36,39]. Given that sodium intake was reduced in both groups, it is
possible that this was more important in reducing BP than the GI. |
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| There were no changes in fasting blood glucose, fasting serum
insulin or HOMA-IR in either group, although, by the end of the
intervention, an additional two and three subjects in the HGI and LGI
groups no longer met the fasting glucose cut-off for MetS. These results
are contrary to what was expected, as previous reports have indicated
a reduced risk of T2D in subjects following LGI diets [40-42]. These
surprising results, however, may have been due to the relatively normal
blood glucose levels at baseline, as it has been proposed that the GI
may affect healthy individuals differently than those with metabolic
disturbances [42], and perhaps the protective effects of a LGI diet
are only evident in those with greater potential for improvement.
Nonetheless, there are reports that a LGI diet does not alter fasting
glucose homeostasis over the short-term [26,27,30,31], and perhaps
more time is needed to observe beneficial changes from a LGI diet. |
| |
| Overall, the intervention had little impact on the dyslipidemia of
the subjects, which may have been due to the large degree of variation
in the baseline lipid values of the subjects and small number of subjects
who completed all twelve weeks. Both groups had significant reductions
in fasting serum TG from baseline, but there was no difference in the
absolute change in TG between the groups. Again this is inconsistent
with previous studies that suggested greater reductions in TG following
short-term LGI diets compared to HGI diets [19,25]. The one major
difference between our study and these others is the addition of the
exercise component, which may have contributed to the TG reductions
in both groups. Nonetheless, there was a significant reduction in the
number of LGI subjects meeting the MetS criteria for TG, with only
a trend being observed in the HGI group. Of interest was that in the
HGI group, there was a reduction in fasting HDL cholesterol and one
additional subject met the MetS cut-off for HDL cholesterol by the
end of the intervention, while the LGI group had no change in HDL
cholesterol. Although the LGI diet did not improve HDL cholesterol
levels, it did not further impair them, as was the case with the HGI diet.
Although previous reports have suggested greater improvements in
cholesterol levels with a LGI diet compared to a HGI diet [26-29,31,39],
the modest changes in HDL levels in the current study indicate a slight
advantage of the LGI diet at maintaining healthy cholesterol levels in
subjects with MetS. |
| |
| The low attendance to the fitness program was unexpected,
as this program was modelled after a similar program with a high
attendance rate [18]. This study ran through the summer which may
have influenced gym attendance, as some subjects expressed difficulties
in attending sessions during this time. It was also unexpected that the
attendance rates would differ significantly between the groups, which
may have been related to their satisfaction with their diet assignment.
Based on anecdotal responses from an exit survey, it is clear that the
LGI group was happier with their diet assignment, which may have
impacted their willingness to commit to three gym sessions per week.
There were no significant differences in the change in strength and
cardiovascular fitness between the groups, indicating that the exercise
program improved overall fitness but that the GI of the diet had no
impact on these fitness improvements. |
| |
| One of the greatest strengths of this intervention was the use of
subjects with MetS, allowing us to measure the effects of the treatment
on each MetS risk factor within a MetS population rather than studying
a healthier population. Previous investigation into the treatment for
MetS relied on overweight or obese subjects [8,9,43], or subjects at risk
for MetS [13,44], however little work has targeted at MetS population
[15,16]. It is important that individuals with MetS are studied directly
as they may react differently to interventions due to the presence of
multiple metabolic abnormalities. Another advantage was the use
of one-on-one nutrition counselling and supervised gym sessions
to increase compliance to the diets and fitness program, and so that
reliance on activity logs was not necessary. The combined diet and
exercise approach is also advantageous, as previous work focused solely
on diet or exercise alone. Furthermore, this macronutrient composition
allowed for the moderate consumption of a wide variety of foods and
could easily be incorporated into a healthy lifestyle. |
| |
| One limitation was the similar level of calorie restriction reported
and the small number of subjects in the original four groups which
prohibited the investigation into whether the LGI version of this diet
would be sufficient to reduce energy intake and promote weight loss.
Additionally, the study was limited by the high attrition rate, and the
subjects who completed the intervention represent a highly motivated
subset of the population and therefore the results may not be applicable
to the general population. Furthermore, the diet information relies on
self-reporting and underreporting is common in the overweight and
obese population [37,38], however, the study was completed in a freeliving
environment and thus it was necessary for subjects to record
their own intake. Finally, there is limited GI information available in
the public domain, and many foods do not have reported GI values
or there are large differences in the values ascribed to similar or the
same foods. This may make it difficult for an individual to apply the
GI concept to their own diet [42]. Without more widely available
information on the GI and better education on the subject, it is possible
that only highly dedicated individuals will be willing to incorporate the
GI into their lifestyle. |
| |
| Conclusions |
| |
| This study demonstrated the beneficial effects of a low fat, moderate
CHO, LGI diet and exercise program, on individuals with MetS, and
supports the use of a lifestyle intervention in the reduction of CVD risk
factors in adults with MetS. The LGI version of the diet had a greater
ability to decrease the number and severity of MetS risk factors, and
increased subject satisfaction and compliance. This research provides valuable knowledge from which future work can be conducted and
from which therapeutic approaches can be developed to reduce the
incidence of MetS and the development of CVD. |
| |
| Authors Contributions |
| |
| Kendra Brett was the lead student researcher on this project and completed the
trial as part of her MSc thesis research. Kelly Meckling is the principle investigator
and graduate advisor for Ms. Brett. Both authors contributed equally to the design
of the trial, the writing of the human participant’s protocol, and the development of
methods, interpretation of results and writing of the manuscript. Both authors have
read and approved the final version. |
| |
| Acknowledgements |
| |
| The authors gratefully acknowledge the participants for their participation in
this study, Mehrnoosh Kashani for her technical assistance with blood sampling,
and Brad Piche, Megan Haines, Anjali Kulkarni and Lisa Prisciak for their help with
data collection and conducting the exercise sessions. This research received no
specific grant from any funding agency in the public, commercial or not-for-profit
sectors. |
| |
|
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