Reductions in visceral fat during weight loss and walking are associated with improvements in VO(2 max)

The Impact of Exercise Training Intensity on Physiological Adaptations and Insulin Resistance in Women with Abdominal Obesity

Abdominal obesity has emerged globally as a major public health issue due to its high prevalence and morbidity. The benefits of physical exercise among the obese population are well documented. However, the optimal exercise intensity for reducing body fat and preventing insulin resistance and metabolic disorders is still under debate. This study aimed to examine the effects of three different intensities of combined endurance and strength training programs on anthropometric variables, physiological and muscular adaptations, and insulin sensitivity. Forty-three obese young women (age 26.4 ± 4.7 years, BMI 33.1 ± 2.5 kg/m2) were randomly assigned to one of four groups: a control group (G0), a moderate-intensity training group (G50, exercising brisk walking at 50% heart rate reserve HRR), a high-intensity training group (G75, exercise jogging at 75% HRR), and an alternated-intensity training group (G50/75, exercise brisk-walking/jogging at 50−75% HRR) with additional strength training once a week for each group. Body composition, waist circumference (WC), fasting blood glucose, insulin sensitivity and resistance (Homa-IR), resting heart rate (RHR), 6-min walk distance (6MWD), 1-repetition maximum (1-RM), and time to exhaustion (TTE) at 45% and 75% maximal voluntary contraction (MVC) for both the flexor and extensor muscle groups of the knees, were recorded before and after three months of exercise training. All training groups showed significant decreases in body mass, BMI, total body fat, body fat percentage, WC, abdominal and visceral mass (p < 0.001), with a greater reduction of body mass and BMI in G75 (p < 0.05). Lean mass increased significantly only in G50/75 (p < 0.05). The insulin sensitivity and Homa-IR decreased in the three training groups (p < 0.01), with greater enhanced resistance in G50 compared to G75 and G50/75 (p < 0.05). In contrast, there were no pre-post changes in all groups for fasting blood glucose (p > 0.05). 1-RM and TTE of the knee flexor and extensor muscles were improved in the three groups (p < 0.01), with greater improvement in G50/75 for 1RM and G75 in most of the TTE parameters (p < 0.05). RHR decreased and 6MWD increased significantly in the three training groups (p < 0.01), with greater 6MWD improvement in G75 (p < 0.05). In conclusion, the three training intensities seem to generate benefits in terms of body composition, physiological and muscular adaptations, and insulin resistance. High training intensity resulted in greater improvements in body mass, BMI, and endurance and strength, whereas moderate training intensity resulted in greater improvements of insulin resistance and homo-IR. Following alternate-intensity training, greater improvements were observed in lean mass and maximal strength performance.

Comparisons of calorie restriction and structured exercise on reductions in visceral and abdominal subcutaneous adipose tissue: a systematic review

Exercise and low-calorie diets are common approaches taken to produce an energy deficit for weight loss in obesity. Changes in visceral and abdominal subcutaneous fat associated with weight loss are important questions but have not yet been concluded. We investigated the relationship between changes in visceral (VAT) and subcutaneous adipose tissue (SAT) areas obtained by abdominal imaging with the change in total body fat. The relevant databases were searched through January 2021 according to the PRISMA guidelines. Sixty-five studies were included. We found that the change in total body fat was associated with changes in both VAT and abdominal SAT areas, but the relationship between total body fat and the abdominal SAT area appeared stronger. Baseline values of VAT and abdominal SAT area were similar in the three treatment groups (calorie restriction, calorie restriction plus exercise, and exercise alone). The reduction in abdominal SAT area for a loss of 1 kg of total body fat was about 10 cm², which was similar among all the treatments. The change in VAT area (-26.3 cm²) was a similar level as the change in abdominal SAT area (-31.5 cm²) in the exercise, whereas in the calorie restriction with and without exercise, the change in VAT area (-33.6 and -51.6 cm², respectively) was approximately half of the reduction of SAT area (-65.1 and -87.2 cm², respectively). Absolute changes in VAT and abdominal SAT areas might differ between interventions for the exercise and calorie restriction with and without exercise.

A Correlational Study on Cardiopulmonary Endurance in Male Patients with New-Onset Type 2 Diabetes

BACKGROUND

Cardiopulmonary exercise tests (CPETs) are widely used non-invasive and reliable functional evaluation methods. This study investigated the correlation between cardiopulmonary endurance indices and plasma glucose levels and abdominal visceral fat in males with new-onset type 2 diabetes.

METHODS

A total of 136 male individuals, who had been treated in the First Hospital of Qinhuangdao City, were selected to form a new-onset type 2 diabetes group (66 cases) and a control group (70 cases); individuals were divided into three groups (Q1, Q2, and Q3) from low to high according to their anaerobic threshold (AT) oxygen uptake (VO₂), AT VO₂/kg (VO₂ per kg of body weight), peak VO₂, peak VO₂/kg, AT heart rate (HR), peak HR, and HR recovery after 1 minute. A cardiopulmonary exercise test was used to determine the VO₂ of each group of subjects for VO₂ max and AT VO₂/kg, HR, and HR recovery after 1 minute. The differences in fat areas and plasma glucose levels were compared under different cardiorespiratory endurance indicators.

RESULTS

Compared with the control group, the abdominal visceral fat (AVF) area, fasting plasma glucose (FPG), and postprandial plasma glucose (PPG) levels increased in the new-onset type 2 diabetes group. Concurrently, AT VO₂, AT VO₂/kg, peak VO₂, peak VO₂/kg, AT HR, peak HR, and 1-minute HR recovery all decreased, and the difference between the groups was statistically significant (P<0.05). The higher the AT VO₂ and peak VO₂ values, the lower the PPG level (P<0.05) and the smaller the area of abdominal visceral fat (P<0.05). The AT VO₂/kg and peak VO₂/kg values were negatively correlated with the abdominal visceral fat area, while other indicators had no obvious relationship with either plasma glucose levels or the area of fat.

CONCLUSION

The levels of blood glucose and visceral fat are correlated with cardiopulmonary function. With the increase in blood glucose levels and visceral fat, the indices of cardiopulmonary function gradually decrease. The correlation between different cardiopulmonary function indices and blood glucose levels and visceral fat was different.

Effects of Caloric Restriction on Cardiorespiratory Fitness, Fatigue, and Disability Responses to Aerobic Exercise in Older Adults With Obesity: A Randomized Controlled Trial

BACKGROUND

Obesity compounds aging-related declines in cardiorespiratory fitness, with accompanying fatigue and disability. This study determined the effects of two different levels of caloric restriction (CR) during aerobic training on cardiorespiratory fitness, fatigue, physical function, and cardiometabolic risk.

METHODS

The INFINITE study was a 20-week randomized trial in 180 older (65-79 years) men and women with obesity (body mass index = 30-45 kg/m2). Participants were randomly assigned to (i) aerobic training (EX; treadmill 4 days/wk for 30 minutes at 65%-70% of heart rate reserve), (ii) EX with moderate (-250 kcal/d) CR (EX + Mod-CR), or (iii) EX with more intensive (-600 kcal/d) CR (EX + High-CR). Cardiorespiratory fitness (peak aerobic capacity, VO2 peak, primary outcome) was determined during a graded exercise test.

RESULTS

One hundred and fifty-five participants returned for 20-week data collection (87% retention). VO2 peak increased by 7.7% with EX, by 13.8% with EX + Mod-CR, and by 16.0% with EX + High-CR, and there was a significant treatment effect (EX + High-CR = 21.5 mL/kg/min, 95% confidence interval = 19.8-23.2; EX + Mod-CR = 21.2 mL/kg/min, 95% confidence interval = 19.4-23.0; EX = 20.1 mL/kg/min, 95% confidence interval = 18.4-21.9). Both CR groups exhibited significantly greater improvement in self-reported fatigue and disability and in glucose control, compared with EX.

CONCLUSION

Combining aerobic exercise with even moderate CR is more efficacious for improving cardiorespiratory fitness, fatigue and disability, and glucose control than exercise alone and is as effective as higher-dose CR.

NAD+ precursor increases aerobic performance in mice

PURPOSE

Nicotinamide riboside (NR) acts as a potent NAD⁺ precursor and improves mitochondrial oxidative capacity and mitochondrial biogenesis in several organisms. However, the effects of NR supplementation on aerobic performance remain unclear. Here, we evaluated the effects of NR supplementation on the muscle metabolism and aerobic capacity of sedentary and trained mice.

METHODS

Male C57BL/6 J mice were supplemented with NR (400 mg/Kg/day) over 5 and 10 weeks. The training protocol consisted of 5 weeks of treadmill aerobic exercise, for 60 min a day, 5 days a week. Bioinformatic and physiological assays were combined with biochemical and molecular assays to evaluate the experimental groups.

RESULTS

NR supplementation by itself did not change the aerobic performance, even though 5 weeks of NR supplementation increased NAD⁺ levels in the skeletal muscle. However, combining NR supplementation and aerobic training increased the aerobic performance compared to the trained group. This was accompanied by an increased protein content of NMNAT3, the rate-limiting enzyme for NAD + biosynthesis and mitochondrial proteins, including MTCO1 and ATP5a. Interestingly, the transcriptomic analysis using a large panel of isogenic strains of BXD mice confirmed that the Nmnat3 gene in the skeletal muscle is correlated with several mitochondrial markers and with different phenotypes related to physical exercise. Finally, NR supplementation during aerobic training markedly increased the amount of type I fibers in the skeletal muscle.

CONCLUSION

Taken together, our results indicate that NR may be an interesting strategy to improve mitochondrial metabolism and aerobic capacity.

Cognitive Effects of Adding Caloric Restriction to Aerobic Exercise Training in Older Adults with Obesity

OBJECTIVE

This study examined the short- and long-term effects of adding caloric restriction to 5 months of aerobic exercise training on executive function in sedentary older adults with obesity.

METHODS

Sedentary adults with obesity aged 65 to 79 years completed a randomized trial investigating the cardiorespiratory benefits of adding moderate (~ 250 kcal) or high (~ 600 kcal) caloric restriction to a 20-week aerobic exercise program. Approximately half (n = 88) completed a cognitive assessment battery at baseline, post intervention, and 18 to 24 months after intervention completion. The primary outcome was an executive function composite score.

RESULTS

In the overall sample, the executive function composite increased 0.114 from baseline to postintervention (P = 0.01). Randomization to caloric restriction did not significantly alter executive function over aerobic exercise alone, nor were there between-group differences on any individual executive function test following the intervention or at long-term follow-up. Adding caloric restriction to exercise was associated with a modest increase in Mini-Mental State Examination score (P = 0.04). In the overall sample, increases from baseline at long-term follow-up were noted in digit symbol and word list recall performance as well.

CONCLUSIONS

Adding caloric restriction to a 20-week aerobic exercise program does not worsen or improve executive function more than exercise alone assessed up to 24 months post randomization.

Effects of a Hypocaloric, Nutritionally Complete, Higher Protein Meal Plan on Regional Body Fat and Cardiometabolic Biomarkers in Older Adults with Obesity

BACKGROUND

Whether improvements in cardiometabolic health following weight loss (WL) are associated with changes in regional body fat distribution (gluteal vs. -android) is not well documented.

METHODS

Older (age: 70 ± 4 years; mean ± SD) adults with obesity were randomized to a 6-month WL program (WL; n = 47), accomplished using a hypocaloric, nutritionally complete, higher protein -(targeting ≥1.0 g/kg/day) meal plan, or a weight stability (WS; n = 49) program. Android, gynoid, visceral, and subcutaneous abdominal fat masses (via dual energy X-ray absorptiometry ) and fasting glucose and lipid profiles were assessed at baseline and 6 months.

RESULTS

The WL group lost more body weight (WL: -8.6% vs. WS: -1.7%, p < 0.01), resulting in a reduction in fat mass at each region only following WL (all p < 0.05). The decline in the ratio of android/gynoid fat mass also was significant only following WL, resulting in greater declines than WS (mean [95% CI]; WL: -0.026 [-0.040 to -0.011] vs. WS: 0.003 [-0.012 to 0.019] g, p < 0.01). The change in the ratio of visceral/subcutaneous abdominal fat mass was not significant in either group and did not differ between groups (WL: 0.65 [-0.38 to 1.68] vs. WS: 0.05 [-1.00 to 1.10] g, p = 0.42). In general, the improvements in glucose and lipid profiles were associated with declines in fat mass at the gynoid and android regions (r's = 0.20-0.42, all p < 0.05), particularly the visceral depot but not the ratios.

CONCLUSION

WL achieved via a hypocaloric, nutritionally complete, higher protein meal plan is effective in reducing body fat in the android, gynoid, and visceral depots, which relate to cardiometabolic improvements.

Does Visceral Fat Estimated by Dual-Energy X-ray Absorptiometry Independently Predict Cardiometabolic Risks in Adults?

BACKGROUND

Abdominal visceral fat, typically measured by computer tomography (CT) or magnetic resonance imaging (MRI), has been shown to correlate with cardiometabolic risks. The purpose of this study was to examine whether a newly developed and validated visceral fat measurement from dual-energy X-ray absorptiometry (DXA) provides added predictive value to the cross-sectional differences of cardiometabolic parameters beyond the traditional anthropometric and DXA adiposity parameters.

METHOD

A heterogeneous cohort of 194 adults (81 males and 113 females) with a BMI of 19 to 54 kg/m(2) participated in this cross-sectional study. Body composition was measured with a DXA densitometer. Visceral fat was then computed with a proprietary algorithm. Insulin sensitivity index (SI, measured by intravenous glucose tolerance test), blood pressures, and lipid profiles, and peak oxygen uptake were also measured as cardiometabolic risk parameters.

RESULTS

DXA-estimated visceral fat mass was associated with HDL cholesterol (regression coefficient [β] = -5.15, P < .01, adjusted R(2) = .21), triglyceride (β = 26.01, P < .01, adjusted R(2) = .14), and peak oxygen uptake (β = -3.15, P < .01, adjusted R(2) = .57) after adjusting for age, gender, and ethnicity. A subanalysis stratifying gender-specific BMI tertiles showed visceral fat, together with ethnicity, was independently associated with SI in overweight men and moderately obese women (second tertile).

CONCLUSIONS

Without requiring additional CT or MRI-based measurements, visceral fat detected by DXA might offer certain advantages over the traditional DXA adiposity parameters as means of assessing cardiometabolic risks.

Pericardial fat loss in postmenopausal women under conditions of equal energy deficit

Weight loss induced by caloric restriction (CR) or aerobic exercise can reduce pericardial fat, and these reductions may help improve cardiovascular health.

PURPOSE

We examined whether combining CR with aerobic exercise enhances pericardial fat loss compared with a CR-only intervention designed to elicit equivalent reductions in body weight. We also examined the relationship between changes in pericardial fat and changes in maximal oxygen consumption (V˙O2max), a measure of cardiorespiratory fitness.

METHODS

Thirty-two abdominally obese postmenopausal women (mean age=58 yr; 78% Caucasian) were randomly assigned to one of three interventions of equal energy deficit (∼2800 kcal·wk) for 20 wk: CR only (n=8), CR + moderate-intensity exercise (n=15), or CR + vigorous-intensity exercise (n=9). The volume of pericardial fat around the coronary arteries was measured by computed tomography.

RESULTS

Women in the CR, CR + moderate-intensity, and CR + vigorous-intensity groups had similar baseline characteristics. The mean ± SD value for pericardial fat before weight loss was 79.07 ± 32.90 cm (range=34.04-152.74 cm), with no difference among groups (P=0.89). All three interventions significantly reduced body weight (15%), waist circumference (10%), and abdominal visceral fat (28%) to a similar degree. There was also a 17% reduction in pericardial fat (-12.75 ± 6.29 cm, P<0.0001), which did not differ among groups (P=0.84). Changes in pericardial fat were inversely correlated with changes in V˙O2max (r=-0.37, P=0.05), but not after adjusting for intervention group and change in body weight.

CONCLUSIONS

Weight loss interventions of equal energy deficit have similar effects on pericardial fat in postmenopausal women, regardless of whether the energy deficit is due to CR alone or CR plus aerobic exercise.

Effects of regular exercise combined with ingestion of vespa amino acid mixture on aerobic fitness and cardiovascular disease risk factors in sedentary older women: a preliminary study

AIM

Vespa amino acid mixture (VAAM) is a nutrient liquid with an amino acid composition that is similar to that produced by hornet (Vespa mandarina) larvae. Animal studies have shown that VAAM may enhance fat metabolism and exercise tolerance. Whether these effects are evident in humans, however, remains to be fully elucidated, especially in older women. The purpose of this study was to investigate whether regular exercise combined with oral ingestion of VAAM improves aerobic fitness and cardiovascular disease risk factors in sedentary older women.

METHODS

Twenty-four older women (aged 63.5±2.6 years) were randomly assigned to either the VAAM ingestion (3000 mg/day, n=12) or placebo (n=12) group. Subjects in both groups participated in 90-min exercise sessions consisting of aerobic exercise and light resistance training on a regular basis two times per week for 12 weeks.

RESULTS

After the 12-week exercise regimen, maximal oxygen uptake was significantly increased in those who ingested VAAM (from 25.3 to 27.7 mL/kg per min), but not in those who ingested the placebo (from 25.4 to 26.9 mL/kg per min). Intra-abdominal fat estimated by computed tomography was significantly reduced in those who ingested VAAM (from 102.0 to 83.3 cm2), but not in those who ingested the placebo (from 92.1 to 82.6 cm2). Total cholesterol, low-density lipoprotein cholesterol and triglyceride levels remained unchanged in both groups.

CONCLUSION

Regular exercise combined with VAAM ingestion may slightly increase aerobic fitness and decrease intra-abdominal fat in sedentary older women. Further investigations with a large sample, however, would be warranted.

The effects of vigorous physical activity on intra-abdominal fat levels: a preliminary study of middle-aged Japanese men

AIM

To examine the effects of vigorous physical activity (PA) on intra-abdominal fat (IF) levels in obese men.

METHODS

Thirty-seven obese men (mean age: 47.6+/-8.6 years) engaged in a 12-week aerobic exercise program on a regular basis (3 days/week). We divided them into low volume of vigorous PA group (n=19) or high volume of vigorous PA group (n=18), based on the median time spent (34.3min/week) in vigorous PA (over 6.1 metabolic equivalents assessed by a single-axis accelerometer) throughout the program.

RESULTS

Regular exercise reduced IF levels (measured by computed tomography) from 188.1+/-53.9cm(2) to 170.3+/-46.6cm(2) for the low volume of vigorous PA group and from 167.9+/-44.3cm(2) to 137.9+/-40.6cm(2) for the high volume of vigorous PA group. Two-way (time x group) ANOVA revealed no significant interactions for the IF level. However, correlation analysis for all participants showed that time spent in vigorous PA throughout the program significantly correlated to IF reductions after adjusting for initial levels of IF, vigorous PA and weight changes (r=-0.42, P=0.02).

CONCLUSION

This study suggests that vigorous PA may affect IF reductions in obese men.

Ovarian function and obesity--interrelationship, impact on women's reproductive lifespan and treatment options

Insulin resistance (IR) is a consequence of obesity, and in women it is often inextricably linked with ovarian function leading to clinical reproductive manifestations such as early menarche onset, subfertility and polycystic ovary syndrome (PCOS). Likewise, the dramatic fall in oestrogen production after menopause may contribute to weight gain and changes in adipose tissue distribution. Overall, women who are obese, especially those with reproductive complications including PCOS, have been identified as specific high risk subgroups for further progression through to prediabetes, type 2 diabetes mellitus (T2DM) and potentially cardiovascular disease (CVD). This review focuses on the interrelationship between the ovarian function and obesity as well as its treatment strategies.

Association between habitual physical activity and parameters of physical fitness in postmenopausal women

OBJECTIVE

To evaluate the association between physical activity and the morphological, functional and physiological components of physical fitness in postmenopausal women.

METHODS

A cross-sectional study of 162 postmenopausal women, 40-65 years of age, who verbally responded to the International Physical Activity Questionnaire applied to evaluate their level of physical activity. Physical fitness was evaluated by measuring body mass index, waist circumference, body fat percentage, maximum oxygen consumption, plasma levels of total and fractional cholesterol, triglycerides and fasting glucose, as well as blood pressure.

RESULTS

Approximately 83.5% of the women were active, principal physical activities being household chores and transportation walking. Approximately 80% of the women were overweight or obese and presented a waist circumference indicative of high or very high risk for cardiovascular disease, and fat percentage above 33%. Over 50% were found to have low oxygen consumption. There were no significant differences between the groups of active and inactive women with respect to mean body mass index (p = 0.43), percentage of body fat (p = 0.60), hip-to-waist ratio (p = 0.93), waist circumference (p = 0.44), maximum VO2 (p = 0.32), total cholesterol (p = 0.43), fasting glucose (p = 0.73), and systolic (p = 0.79) or diastolic blood pressure (p = 0.48). Adjusted prevalence ratios also showed no significant differences between the groups.

CONCLUSIONS

Habitual physical activity is not associated with variations in the components that are used to describe physical fitness. It is important to encourage physical activity and provide guidelines to ensure that it is carried out in the quantity, duration and intensity required for improving physical fitness level and obtaining health benefits.

Comparable reduction of the visceral adipose tissue depot after a diet-induced weight loss with or without aerobic exercise in obese subjects: a 12-week randomized intervention study

OBJECTIVE

Weight loss with preferential effect on the visceral adipose tissue (VAT) depot could have important clinical benefits. In this study, we investigated the independent and combined effect of regular exercise and diet induced weight loss on body fat distribution. DESIGN; Randomized control design of i) exercise-only (EXO; 12 weeks of exercise without diet-restriction), ii) hypocaloric-diet (DIO; 8 weeks of very low energy diet (VLED 600 kcal/day) followed by 4-weeks weight maintenance diet) and iii) hypocaloric-diet and exercise (DEX; 8 weeks VLED 800 kcal/day+a 4-week weight maintenance diet combined with exercise throughout the 12 weeks).

SUBJECTS

Seventy-nine obese males and females were included.

MEASUREMENTS

Body fat distribution was quantified by magnetic resonance imaging (MRI)-technology.

RESULTS

In the EXO group, the weight loss (3.5 kg) and the relative reduction in VAT (18%) was significantly lower compared with the weight losses in the DIO and DEX groups (12.3 kg; P<0.01) and to the reduction in VAT (30-37%; P<0.01). In all the three groups, the relative reduction of VAT was higher as compared with the reduction in fat mass (FM; combining all fat depots determined by MRI; P<0.01 for all comparisons). The changes in VAT were associated with changes in FM and related to the initial VAT/FM ratio (r(2)=0.72; P<0.01).

CONCLUSION

Exercise has no additional effects in reduction of the VAT depot, compared with the major effects of hypocaloric diet alone. In addition, the effects of exercise per se on VAT are relatively limited. The effects on the VAT depot are closely associated with changes in total FM.

Allometric relationship between changes of visceral fat and total fat mass

OBJECTIVE

To elucidate the mathematical relationship between changes of visceral adipose tissue (VAT) and total body fat mass (FM) during weight loss.

DESIGN

We hypothesized that changes of VAT mass are allometrically related to changes of FM, regardless of the type of weight-loss intervention, as defined by the differential equation dVAT/dFM=k x VAT/FM, where k is a dimensionless constant. We performed a systematic search of the published literature for studies that included measurements of VAT changes via magnetic resonance imaging (MRI) or computed tomography (CT) imaging along with measurements of FM changes by dual-energy X-ray absorptiometry, hydrodensitometry, air-displacement plethysmography or whole-body MRI or CT imaging. We then examined whether or not the data could be explained by the allometric model.

RESULT

We found 37 published studies satisfying our search criteria, representing 1407 men and women of various ethnicities, degrees of adiposity and weight-loss interventions. The hypothesized allometric equation relating changes of VAT and FM accurately modeled the data for both men and women and for all methods of weight loss studied. The best-fit value for the dimensionless constant was k=1.3+/-0.1 and the resulting model had an R(2)=0.73.

CONCLUSION

This is the first report to reveal an allometric relationship between changes of VAT and FM that holds for both genders as well as a wide variety of weight-loss interventions including bariatric surgery, caloric restriction with or without exercise and exercise alone. We conclude that changes of VAT are primarily determined by FM changes as well as the initial VAT to FM ratio.

Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets

BACKGROUND

Consuming foods low in energy density (kcal/g) decreases energy intake over several days, but the effectiveness of this strategy for weight loss has not been tested.

OBJECTIVE

The effects on weight loss of 2 strategies for reducing the energy density of the diet were compared over 1 y.

DESIGN

Obese women (n = 97) were randomly assigned to groups counseled either to reduce their fat intake (RF group) or to reduce their fat intake and increase their intake of water-rich foods, particularly fruit and vegetables (RF+FV group). No goals for energy or fat intake were assigned; the subjects were instructed to eat ad libitum amounts of food while following the principles of their diet.

RESULTS

After 1 y, study completers (n = 71) in both groups had significant decreases in body weight (P < 0.0001). Subjects in the RF+FV group, however, had a significantly different pattern of weight loss (P = 0.002) than did subjects in the RF group. After 1 y, the RF+FV group lost 7.9 +/- 0.9 kg and the RF group lost 6.4 +/- 0.9 kg. Analysis of all randomly assigned subjects also showed a different pattern of weight loss between groups (P = 0.021). Diet records indicated that both groups had similar reductions in fat intake. The RF+FV group, however, had a lower dietary energy density than did the RF group (P = 0.019) as the result of consuming a greater weight of food (P = 0.025), especially fruit and vegetables (P = 0.037). The RF+FV group also reported less hunger (P = 0.003).

CONCLUSION

Reducing dietary energy density, particularly by combining increased fruit and vegetable intakes with decreased fat intake, is an effective strategy for managing body weight while controlling hunger.

The relative benefits of endurance and strength training on the metabolic factors and muscle function of people with type 2 diabetes mellitus

OBJECTIVE

To compare the effects of a 4-month strength training (ST) versus aerobic endurance training (ET) program on metabolic control, muscle strength, and cardiovascular endurance in subjects with type 2 diabetes mellitus (T2D).

DESIGN

Randomized controlled trial.

SETTING

Large public tertiary hospital.

PARTICIPANTS

Twenty-two T2D participants (11 men, 11 women; mean age +/- standard error, 56.2+/-1.1 y; diabetes duration, 8.8+/-3.5 y) were randomized into a 4-month ST program and 17 T2D participants (9 men, 8 women; mean age, 57.9+/-1.4 y; diabetes duration, 9.2+/-1.7 y) into a 4-month ET program.

INTERVENTIONS

ST (up to 6 sets per muscle group per week) and ET (with an intensity of maximal oxygen consumption of 60% and a volume beginning at 15 min and advancing to a maximum of 30 min 3x/wk) for 4 months.

MAIN OUTCOME MEASURES

Laboratory tests included determinations of blood glucose, glycosylated hemoglobin (Hb A1c), insulin, and lipid assays.

RESULTS

A significant decline in Hb A1c was only observed in the ST group (8.3%+/-1.7% to 7.1%+/-0.2%, P=.001). Blood glucose (204+/-16 mg/dL to 147+/-8 mg/dL, P<.001) and insulin resistance (9.11+/-1.51 to 7.15+/-1.15, P=.04) improved significantly in the ST group, whereas no significant changes were observed in the ET group. Baseline levels of total cholesterol (207+/-8 mg/dL to 184+/-7 mg/dL, P<.001), low-density lipoprotein cholesterol (120+/-8 mg/dL to 106+/-8 mg/dL, P=.001), and triglyceride levels (229+/-25 mg/dL to 150+/-15 mg/dL, P=.001) were significantly reduced and high-density lipoprotein cholesterol (43+/-3 mg/dL to 48+/-2 mg/dL, P=.004) was significantly increased in the ST group; in contrast, no such changes were seen in the ET group.

CONCLUSIONS

ST was more effective than ET in improving glycemic control. With the added advantage of an improved lipid profile, we conclude that ST may play an important role in the treatment of T2D.

Quantitative trait loci for abdominal fat and BMI in Hispanic-Americans and African-Americans: the IRAS Family study

OBJECTIVE

To conduct linkage analysis for body mass index (BMI, kg/m2), waist-to-hip ratio (WHR), visceral adipose tissue mass (VAT, cm2) and subcutaneous adipose tissue mass (SAT, cm2) using a whole genome scan.

DESIGN

Cross-sectional family study.

STUDY SUBJECTS

African-American families from Los Angeles (AA, n=21 extended pedigrees) and Hispanic-American families (HA) from San Antonio, TX (HA-SA, n=33 extended pedigrees) and San Luis Valley, CO (HA-SLV, n=12 extended pedigrees), totaling 1049 individuals in the Insulin Resistance and Atherosclerosis (IRAS) Family Study.

MEASUREMENTS

VAT and SAT were measured using a computed tomography scan obtained at the fourth and fifth lumbar vertebrae. All phenotypes were adjusted for age, gender, and study center. VAT, SAT, and WHR were analyzed both unadjusted and adjusted for BMI.

RESULTS

Significant linkage to BMI was found at D3S2387 (LOD=3.67) in African-Americans, and at D17S1290 in Hispanic-Americans (LOD=2.76). BMI-adjusted WHR was linked to 12q13-21 (D12S297 (LOD=2.67) and D12S1052 (LOD=2.60)) in Hispanic-Americans. The peak LOD score for BMI-adjusted VAT was found at D11S2006 (2.36) in Hispanic families from San Antonio. BMI-adjusted SAT was linked to D5S820 in Hispanic families (LOD=2.64). Evidence supporting linkage of WHR at D11S2006, VAT at D17S1290, and SAT at D1S1609, D3S2387, and D6S1056 was dependent on BMI, such that the LOD scores became nonsignificant after adjustment of these phenotypes for BMI.

CONCLUSIONS

Our findings both replicate previous linkage regions and suggest novel regions in the genome that may harbor quantitative trait locis contributing to variation in measures of adiposity.

Treatment of insulin resistance in diabetes mellitus

Insulin resistance is a condition in which the glycemic response to insulin is less than normal. The change in insulin sensitivity leads to several sets of responses. One set effects the beta cell and leads to its accelerated destruction and the development of diabetes mellitus. The other set generates a series of nontraditional cardiovascular risk factors that result in accelerated atherosclerosis. Both of these sets of responses may have impacts on other tissues such as the nervous system. Insulin resistance is probably the result of increased visceral adiposity with increased release of free fatty acids and cytokines and a decreased release of adiponectin. Treatment of insulin resistance and its associated abnormalities can be achieved by lifestyle modification which results in weight loss, by drugs that reverse the abnormal adipocyte effects, by drugs that improve insulin sensitivity at the level of the liver and by anti-inflammatory agents that block activation of the nuclear factor kappa B cascade.

Measurement of abdominal fat by CT compared to waist circumference and BMI in explaining the presence of coronary calcium

OBJECTIVE

To evaluate the association between standard and computed tomography (CT)-based measures of obesity and subclinical atherosclerosis, defined as coronary artery calcium (CAC) by Electron Beam Computed Tomography (EBCT).

DESIGN

Cross-sectional, observational study of anthropometric and CT obesity measures and presence of CAC.

SUBJECTS

Participants were 383 men and 379 women, aged 20-58 y and asymptomatic for coronary artery disease (CAD).

MEASUREMENTS

Intra-abdominal fat (IAF) and subcutaneous fat (SQF) were measured at the level of lumbar 2-3 and 4-5 spaces, using EBCT. Body mass index (BMI) was calculated from height and weight, and minimum waist circumference and maximum hip circumference were measured. CAC was measured by EBCT.

RESULTS

In both men and women, BMI, waist circumference, IAF, and SQF were significantly related to CAC. However, BMI or waist circumference explained variation in the presence of CAC as well as IAF or SQF, univariately and after adjustment for additional cardiovascular risk factors.

CONCLUSION

CT-based obesity exposure measures are not superior to BMI or waist circumference in association studies of subclinical CAD.

Low intensity endurance exercise targeted for lipid oxidation improves body composition and insulin sensitivity in patients with the metabolic syndrome

BACKGROUND

To investigate the effects of individualized training on the metabolic syndrome.

METHODS

Twenty-eight patients, suffering from the metabolic syndrome were studied before and after 2 months of training and compared to eleven patients who did not follow any training. All the patients were overweight. Training was individualized at the point where fat oxidation was maximal (LIPOX(max)) as determined by calorimetry.

RESULTS

The patients exhibited a significant reduction in body weight (- 2.6 +/- 0.7 kg; P=0.002), fat mass (- 1.55 +/- 0.5 kg; P=0.009), waist (- 3.53 +/- 1.3 cm; P<0.05) and hip (- 2.21 +/- 0.9 cm; P<0.05) circumferences, and improved the ability to oxidize lipids at exercise (crossover point: + 31.7 +/- 5.8 W; P<0.0001; LIPOX(max): + 23.5 +/- 5.6 W; P<0.0001; lipid oxidation: + 68.5 +/- 15.4 mg.min(-1); P=0.0001). No clear improvement in either lipid parameters or fibrinogen were observed. The surrogates of insulin sensitivity evidenced a decrease in insulin resistance: HOMA%S (software): + 72.93 +/- 32.64; p<0.05; HOMA-IR (simplified formula): - 2.42 +/- 1.07; P<0.05; QUICKI: + 0.02 +/- 0.004; P<0.01; SI=40/I: + 3.28 +/- 1.5; P<0.05. Significant correlations were found between changes in body weight and HOMA-IR and between changes in LIPOX(max) and QUICKI.

CONCLUSIONS

Individualized aerobic training improves lipid oxidation, body composition and insulin resistance.

Central abdominal fat and endogenous hormones during the menopausal transition

OBJECTIVE

To investigate the effect of endogenous hormone levels on central abdominal fat during the menopausal transition in a population-based cohort of Australian-born women.

DESIGN

Prospective observational study.

SETTING

Population-based sample. Body composition was assessed in the Royal Melbourne Hospital, and interviews were conducted at the patient's home.

SUBJECT(S)

One hundred two women from the Melbourne Women's Midlife Health Project. Data, physical measures, and blood were obtained by interview when the longitudinal study commenced (baseline) and at the time of the total body scan approximately 5 years later. Body composition was measured using dual-energy X-ray absorptiometry.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURES

Total body fat and central abdominal fat.

RESULT(S)

The 102 women were either premenopausal or in the early menopausal transition at baseline. At the time of their dual-energy X-ray absorptiometry scan, 31 were in the early menopausal transition, 22 were in the late menopausal transition, and 49 were postmenopausal. Multiple regression analysis found that total percentage of body fat was associated with weight measures, whereas central abdominal fat was also positively associated with baseline free T index (FTI) and with the increase in FTI since baseline.

CONCLUSION(S)

The major hormonal change associated with central adiposity during the menopausal transition is the increase in the FTI. This effect is significant even after allowing for baseline and final weight.

Comparison of VO2max and disease risk factors between perimenopausal and postmenopausal women

OBJECTIVE

This study determines whether maximal oxygen consumption (VO2 max) is higher in perimenopausal women compared with similarly aged postmenopausal women and whether the lower VO2 max in postmenopausal women is associated with a higher total and visceral fat mass, less favorable lipid and glucose metabolism, and lower bone mineral density (BMD).

DESIGN

Participants were 18 perimenopausal women (mean +/- SD; irregular menstrual cycle in the past 6 months) aged 49 +/- 4 years and 18 postmenopausal women (no menstrual cycle in the past year) aged 52 +/- 2 years who were matched for body mass index and race. Women were sedentary, and none were on hormone replacement therapy. Body composition (dual-energy x-ray absorptiometry and CT), VO2 max, fasting concentrations of sex steroid hormones, lipoproteins, insulin, and glucose were determined.

RESULTS

VO2 max was 17% lower (22 +/- 3 v 27 +/- 7 mL.kg.min; P </= 0.01) and resting metabolic rate was 5% lower (P = 0.06) in postmenopausal women compared with perimenopausal women. Percent body fat was 11% higher, and visceral fat area was 42% higher in postmenopausal women, whereas total body and lumbar spine (L2 -L4) BMD were 5% and 11% lower, respectively (P < 0.05). Low-density lipoprotein cholesterol, low-density lipoprotein cholesterol.high-density lipoprotein cholesterol ratio, and fasting glucose concentrations were 21%, 20%, and 8% higher, respectively, in postmenopausal versus perimenopausal women (P < 0.05). Except for total body and lumbar spine BMD, the effect of menopause status on these variables is independent of age. In all women, percent body fat, visceral adipose tissue, and low-density lipoprotein cholesterol.high-density lipoprotein cholesterol ratios related indirectly to VO2 max (P < 0.05).

CONCLUSIONS

Our data suggest that postmenopausal women have a lower VO2 max than perimenopausal women of a similar age and adiposity, which may be associated with an increased risk of total and central obesity and cardiovascular disease.