Benefits of a year-long workplace weight loss program on cardiovascular risk factors

Objective: To assess the effectiveness of a year-long workplace weight loss program in reducing risk factors of coronary heart disease.

Design: A randomised, controlled study of low fat (25% of dietary energy) diet- and/or moderate exercise-induced weight loss interventions in free-living, middle-aged men. Compliance was monitored from food and activity diaries at monthly blood pressure measurement sessions. Blood was sampled and body composition determined from dual energy X-ray absorptiometry before and after 12 months.

Subjects and setting: Fifty-eight overweight men (mean [+ or -] SD age: 43.4 [+ or -] 5.7 years; BMI 29.0 [+ or -] 2.6 kg/[m.sup.2]), recruited from a national corporation, were instructed into diet (n = 18) exercise (a 21) or control (n = 19) groups over 12 months; 16 control subjects combined diet and exercise (n = 16) for the subsequent 12 months.

Main outcome measures: At 12 months, weight, total and regional fat and lean mass, dietary energy and percentage dietary fat intake, physical activity indices, systolic and diastolic blood pressure, serum insulin, blood lipids and lipoproteins.

Statistical analyses: Differences between groups were tested using analysis of variance with Scheffe post hoc test. Differences between pre- and post-intervention variables were tested using Students' paired t-tests. Pearson's correlation coefficient and univariate linear regression identified association between dependent variables, multiple stepwise regression identified specific predictors.

Results: Weight loss with either diet or exercise resulted in a reduction in systolic blood pressure (-3.3 [+ or -] 1.7%), diastolic blood pressure (-4.8 [+ or -] 1.3%) and LDL cholesterol (-3.9 [+ or -] 2.8%), a rise in HDL cholesterol (+10.0 [+ or -] 3.8%) and a change in the LDL/HDL ratio (-8.9 [+ or -] 3.5%). Abdominal fat loss (-26.8 [+ or -] 3.6% after diet; -16.6 [+ or -] 4.5% after exercise; -21.0 [+ or -] 4.7% after diet and exercise) was the strongest predictor of change in blood pressure: twenty percent abdominal fat loss predicted a percentage fall of 2.4 [+ or -] 0.05% in systolic blood pressure and 5.4 [+ or -] 0.07% in diastolic blood pressure. Greater abdominal fat loss was associated with the greatest decrease in serum insulin (P < 0.05).

Conclusion: Modest changes in diet and exercise effected by a low cost workplace-based education program achieved weight loss, loss of abdominal fat, reduced blood pressure and serum insulin and improved blood lipid concentrations. (Nutr Diet 2002;59:87-96)

Pyruvate dehydrogenase activation and kinase expression in human skeletal muscle during fasting

Fasting forces adaptive changes in whole body and skeletal muscle metabolism that increase fat oxidation and decrease the oxidation of carbohydrate. We tested the hypothesis that 40 h of fasting would decrease pyruvate dehydrogenase (PDH) activity and increase PDH kinase (PDK) isoform mRNA expression in human skeletal muscle. The putative transcriptional activators of PDK isozymes, peroxisome proliferator-activated receptor-α (PPAR-α) protein, and forkhead homolog in rhabdomyosarcoma (FKHR) mRNA were also measured. Eleven healthy adults fasted after a standard meal (25% fat, 60% carbohydrate, 15% protein) with blood and skeletal muscle samples taken at 3, 15, and 40 h postprandial. Fasting increased plasma free fatty acid, glycerol, and β-hydroxybutyrate concentrations and decreased glucose and insulin concentrations. PDH activity decreased from 0.88 ± 0.11 mmol acetyl-CoA · min^-1 · kg wet muscle wt^-1 at 3 h to 0.62 ± 0.10 (P = not significant) and 0.39 ± 0.06 (P < 0.05) mmol · min^-1 · kg wet mass^-1 after 15 and 40 h of fasting. Although all four PDK isoforms were expressed in human skeletal muscle, PDK^-2 and -4 mRNA were the most abundant. PDK^-1 and ^-3 mRNA abundance was ~1 and 15% of the PDK^-2 and 4^- levels, respectively. The 40-h fast had no effect on PDK^-1, ^-2, and ^-3 mRNA expression. PDK-4 mRNA was significantly increased ~3-fold after 15 h and ~14-fold after 40 h of fasting. Skeletal muscle PPAR-α protein and FKHR mRNA abundance were unaffected by the fast. The results suggest that decreased PDH activation after 40 h of fasting may have been a function of the large increase in PDK-4 mRNA expression and possible subsequent increase in PDK protein and activity. The changes in PDK-4 expression and PDH activity did not coincide with increases in the transcriptional activators PPAR-α and FKHR.

Regulation of metabolic genes in human skeletal muscle by short-term exercise and diet manipulation

Changes in dietary macronutrient intake alter muscle and blood substrate availability and are important for regulating gene expression. However, few studies have examined the effects of diet manipulation on gene expression in human skeletal muscle. The aim of this study was to quantify the extent to which altering substrate availability impacts on subsequent mRNA abundance of a subset of carbohydrate (CHO)- and fat-related genes. Seven subjects consumed either a low- (LOW; 0.7 g/kg body mass CHO) or high- (HIGH; 10 g/kg body mass CHO) CHO diet for 48 h after performing an exhaustive exercise bout to deplete muscle glycogen stores. After intervention, resting muscle and blood samples were taken. Muscle was analyzed for the gene abundances of GLUT4, glycogenin, pyruvate dehydrogenase kinase-4 (PDK-4), fatty acid translocase (FAT/CD36), carnitine palmitoyltransferase I (CPT I), hormone-sensitive lipase (HSL), β-hydroxyacyl-CoA dehydrogenase (΄β-HAD), and uncoupling binding protein-3 (UCP3), and blood samples for glucose, insulin, and free fatty acid (FFA) concentrations. Glycogen-depleting exercise and HIGH-CHO resulted in a 300% increase in muscle glycogen content (P < 0.001) relative to the LOW-CHO condition. FFA concentrations were twofold higher after LOW- vs. HIGH-CHO (P < 0.05). The exercise-diet manipulation exerted a significant effect on transcription of all carbohydrate-related genes, with an increase in GLUT4 and glycogenin mRNA abundance and a reduction in PDK-4 transcription after HIGH-CHO (all P < 0.05). FAT/CD36 (P < 0.05) and UCP3 (P < 0.01) gene transcriptions were increased following LOW-CHO. We conclude that 1) there was a rapid capacity for a short-term exercise and diet intervention to exert coordinated changes in the mRNA transcription of metabolic related genes, and 2) genes involved in glucose regulation are increased following a high-carbohydrate diet.

Relationship between platelet phospholipid FA and mean platelet volume in healthy men

Increased mean platelet volume (MPV) has been suggested as an independent risk factor for acute myocardial infarction and the increased reactivity of large platelets. The aim of this study was to investigate the correlation between platelet phospholipid (PL) PUFA composition and MPV in 139 free-living healthy men ages 20-55 yr (vegans, n = 18; ovolacto vegetarians, n = 43; moderate meat-eaters, n = 60; and high meateaters, n = 18). Each subject completed a semiquantitative Food Frequency Questionnaire and gave a blood sample. Platelet PL FA composition and MPV were determined by standard methods. MPV was significantly greater in the vegans than in the ovolacto vegetarian, moderate, or high meat-eater groups (P < 0.01). Both vegan and ovolacto vegetarian groups had significantly higher platelet PL 18:2n-6 and 22:4n-6, and lower 20:5n-3 and 22:6n-3 compared with the moderate and high meat-eater groups. The vegans demonstrated a significant reduction in 20:4n-6 and 22:5n-3 compared with the ovolacto vegetarian, high meat-eater, and moderate meat-eater groups. Bivariate analysis results showed that MPV was significantly positively correlated with platelet PL 18:2n-6 (P = 0.048) and negatively correlated with 20:3n-6 (P = 0.02), 20:5n-3 (P = 0.005), and 22:5n-3 (P< 0.0001), respectively. In a multiple linear regression analysis, after controlling for potential confounding factors such as dietary group, age, exercise, body mass index, and dietary polyunsaturated and saturated fat, cholesterol, carbohydrate, and fiber intake, the MPV was still strongly negatively correlated with platelet PL 20:3n-6 (P = 0.003) and 22:5n-3 (P = 0.001). The present data suggest that 22:5n-3 and 20:3n-6 may play a role in the structural function of the platelet membrane.

The influence of fish, meat and polyunsaturated fat intakes on platelet phopholipid polyunsaturated fatty acid in male Melbourne Chinese and Caucasian

Objective: The aims of this study were to investigate (1) platelet phospholipid (PL) polyunsaturated fatty acid (PUFA) composition in subjects who were the Melbourne Chinese migrants, compared with those who were the Melbourne Caucasians and (2) the relationship between platelet PL PUFA and intake of fish, meat and PUFA.

Design: Cross-sectional comparison of the Melbourne Chinese and Caucasians.

Setting: Free-living male subjects.

Subjects: Ninety-seven Melbourne Chinese migrants and 78 Melbourne Caucasians who were recruited in Melbourne.

Outcome measures: Dietary intake was assessed using a semi-quantitative food frequency questionnaire. The platelet PUFA was measured by gas-liquid chromatography.

Results: The Melbourne Chinese had significantly higher proportions of platelet PL 20:5n-3 (P=0.006), 22:6n-3 (P<0.0001), total n-3 (P=0.027) and 22:5n-6 (P=0.0002), and a significantly higher intake of fish (P=0.012) and white meat (P=0.0045) compared with the Melbourne Caucasians. In addition, the Melbourne Chinese had significantly lower proportions of 20:3n-6 (P=0.023), 20:4n-6 (P<0.002), 22:4n-6 (P<0.0001), total n-6 (P=0.037), 22:5n-3 (P<0.0001) and ratio of n-6/n-3 (P=0.011), and a significantly lower intake of red and total meat (P<0.0001) than the Melbourne Caucasians. Fish consumption was significantly positively correlated with platelet PL 20:5n-3 and 22:6n-3, and significantly negatively correlated with 22:5n-3 (P<0.05). Meat consumption was significantly positively correlated with 22:5n-3 and significantly negatively correlated with 22:5n-6, 20:5n-3 and 22:6n-3 (P<0.05). Dietary PUFA intake was significantly positively correlated with 20:3n-6, 22:4n-6 and 22:5n-3, and significantly negatively correlated with 22:5n-6, 20:5n-3 and 22:6n-3 (P<0.05).

Conclusions: Compared with Caucasians, the Melbourne Chinese had a significantly higher level of platelet PL n-3 PUFA, which might contribute to the low CVD mortality in this population. Platelet PL 20:5n-3 and 22:6n-3 were significantly positively correlated with fish intake, and negatively significantly correlated with dietary intake of meat and PUFA, while 22:5n-3 was significantly positively correlated with dietary meat and PUFA intake, and significantly negatively correlated with fish intake. Dietary intake of PUFA and fish are potential confounding factors for assessing the effects of meat consumption on platelet PL individual PUFA. Dietary intake of PUFA and meat did not influence the incorporation of fish long chain n-3 PUFA to platelet PL in this study population.

Thrifty metabolism that favors fat storage after caloric restriction: a role for skeletal muscle phosphatidylinositol-3-kinase activity and AMP-activated protein kinase

Energy conservation directed at accelerating body fat recovery (or catch-up fat) contributes to obesity relapse after slimming and to excess fat gain during catch-up growth after malnutrition. To investigate the mechanisms underlying such thrifty metabolism for catch-up fat, we tested whether during refeeding after caloric restriction rats exhibiting catch-up fat driven by suppressed thermogenesis have diminished skeletal muscle phosphatidylinositol-3-kinase (PI3K) activity or AMP-activated protein kinase (AMPK) signaling—two pathways required for hormone-induced thermogenesis in ex vivo muscle preparations. The results show that during isocaloric refeeding with a low-fat diet, at time points when body fat, circulating free fatty acids, and intramyocellular lipids in refed animals do not exceed those of controls, muscle insulin receptor substrate 1-associated PI3K activity (basal and in vivo insulin-stimulated) is lower than that in controls. Isocaloric refeeding with a high-fat diet, which exacerbates the suppression of thermogenesis, results in further reductions in muscle PI3K activity and in impaired AMPK phosphorylation (basal and in vivo leptin-stimulated). It is proposed that reduced skeletal muscle PI3K/AMPK signaling and suppressed thermogenesis are interdependent. Defective PI3K or AMPK signaling will reduce the rate of substrate cycling between de novo lipogenesis and lipid oxidation, leading to suppressed thermogenesis, which accelerates body fat recovery and furthermore sensitizes skeletal muscle to dietary fat-induced impairments in PI3K/AMPK signaling.—Summermatter, S., Mainieri, D., Russell, A. P., Seydoux, J., Montani, J. P., Buchala, A., Solinas, G., Dulloo, A. G. Thrifty metabolism that favors fat storage after caloric restriction: a role for skeletal muscle phosphatidylinositol-3-kinase activity and AMP-activated protein kinase.

Dietary approaches for weight loss with increased intakes of fruit, vegetables and dairy products

Aim: To assess the effectiveness of specific advice for increasing fruit, vegetable and dairy intake in free-living men participating in a weight loss study.

Methods: Subjects were randomised to one of two 12-week weight loss diets, either the WELL with daily targets of four serves of fruit, four serves of vegetables and three serves of dairy or a low fat diet (LF) with general advice to increase fruit and vegetable intake. Three-day food group diaries and a food frequency questionnaire assessed intake.

Results: Fifty-four overweight/obese male adults completed the study (WELL, n = 27; LF, n = 27; body mass index (mean ± standard deviation), 30.4 ± 2.5 kg/m²; age, 47.7 ± 9.5 years). There was no difference in mean weight change between groups (WELL, −4.8 ± 3.3 kg; LF, −4.6 ± 3.1 kg). Subjects on the WELL diet had greater (mean difference ± standard error) fruit (0.7 ± 0.2 serves/day), vegetable (1.2 ± 0.2 serves/day) and dairy (1.1 ± 0.1 serves/day) intakes than the LF group (measured by the food group diaries) (all P < 0.01). The WELL group reached the daily target for fruit from week 1 (4.7 ± 1.4 serves/day), vegetables by week 6 (4.1 ± 1.5 serves/day) and for dairy by week 8 (3.0 ± 0.8 serves/day).

Conclusions: Providing specific dietary targets to men for weight loss appears to promote greater consumption of fruit, vegetable and dairy foods than providing general dietary advice. Meeting dietary targets appears to require different adjustment periods depending on the food type.

The cost-effectiveness of removing television advertising of high-fat and/or high-sugar food and beverages to Australian children

Objective: To model the health benefits and cost-effectiveness of banning television (TV) advertisements in Australia for energy-dense, nutrient-poor food and beverages during children's peak viewing times.

Methods: Benefits were modelled as changes in body mass index (BMI) and disability-adjusted life years (DALYs) saved. Intervention costs (AUD$) were compared with future health-care cost offsets from reduced prevalence of obesity-related health conditions. Changes in BMI were assumed to be maintained through to adulthood. The comparator was current practice, the reference year was 2001, and the discount rate for costs and benefits was 3%. The impact of the withdrawal of non-core food and beverage advertisements on children's actual food consumption was drawn from the best available evidence (a randomized controlled trial of advertisement exposure and food consumption). Supporting evidence was found in ecological relationships between TV advertising and childhood obesity, and from the effects of marketing bans on other products. A Working Group of stakeholders provided input into decisions surrounding the modelling assumptions and second-stage filters of 'strength of evidence', 'equity', 'acceptability to stakeholders', 'feasibility of implementation', 'sustainability' and 'side-effects'.

Results: The intervention had a gross incremental cost-effectiveness ratio of AUD$ 3.70 (95% uncertainty interval (UI) $2.40, $7.70) per DALY. Total DALYs saved were 37 000 (95% UI 16 000, 59 000). When the present value of potential savings in future health-care costs was considered (AUD$ 300m (95% UI $130m, $480m), the intervention was 'dominant', because it resulted in both a health gain and a cost offset compared with current practice.

Conclusions: Although recognizing the limitations of the available evidence, restricting TV food advertising to children would be one of the most cost-effective population-based interventions available to governments today. Despite its economic credentials from a public health perspective, the initiative is strongly opposed by food and advertising industries and is under review by the current Australian government.

Green tea, black tea, and epigallocatechin modify body composition, improve glucose tolerance, and differentially alter metabolic gene expression in rats fed a high-fat diet

The mechanisms of how tea and epigallocatechin-3-gallate (EGCG) lower body fat are not completely understood. This study investigated long-term administration of green tea (GT), black tea (BT), or isolated EGCG (1 mg/kg per day) on body composition, glucose tolerance, and gene expression related to energy metabolism and lipid homeostasis; it was hypothesized that all treatments would improve the indicators of metabolic syndrome. Rats were fed a 15% fat diet for 6 months from 4 weeks of age and were supplied GT, BT, EGCG, or water. GT and BT reduced body fat, whereas GT and EGCG increased lean mass. At 16 weeks GT, BT, and EGCG improved glucose tolerance. In the liver, GT and BT increased the expression of genes involved in fatty acid synthesis (SREBP-1c, FAS, MCD, ACC) and oxidation (PPAR-α, CPT-1, ACO); however, EGCG had no effect. In perirenal fat, genes that mediate adipocyte differentiation were suppressed by GT (Pref-1, C/EBP-β, and PPAR-γ) and BT (C/EBP-β), while decreasing LPL, HSL, and UCP-2 expression; EGCG increased expression of UCP-2 and PPAR-γ genes. Liver triacylglycerol content was unchanged. The results suggest that GT and BT suppressed adipocyte differentiation and fatty acid uptake into adipose tissue, while increasing fat synthesis and oxidation by the liver, without inducing hepatic fat accumulation. In contrast, EGCG increased markers of thermogenesis and differentiation in adipose tissue, while having no effect on liver or muscle tissues at this dose. These results show novel and separate mechanisms by which tea and EGCG may improve glucose tolerance and support a role for these compounds in obesity prevention.

Regulation of fat oxidative genes in human skeletal muscle

The ability of skeletal muscle to adapt fat oxidation rates is important for human health. Lipid metabolism requires the involvement of many proteins encoded by their corresponding genes. This thesis demonstrates that manipulating plasma free fatty acid levels alters the expression of selected genes involved in regulating fatty acid metabolism.

Diet high in monounsaturated fat does not have a different effect on arterial elasticity than a low-fat, high-carbohydrate diet

Objective : To compare the effects of a modified-fat diet high in monounsaturated fat, and a low-fat/high-carbohydrate diet on arterial elasticity.
Design : Randomized crossover design; each diet period was 1 month and a 2-week wash out period occurred in between.
Subjects/setting : Thirty healthy, free-living, nonsmoking men and women were recruited from the Melbourne, Australia, metropolitan region of Australia. Men were aged 35 to 55 years and postmenopausal women were aged 50 to 60 years and were not taking hormone replacement therapy. Twenty-eight subjects completed the study.
Intervention : Two diets of equal energy value: a modified-fat diet and a low-fat/high-carbohydrate diet; the modified-fat diet had 3 times more energy from monounsaturated fat.
Main outcome measures : Arterial elasticity and serum lipoprotein concentrations.
Statistical analysis : The general linear model was used to investigate overall effect and any carryover or order effects. Paired t test and the general linear model were used to compare the results from the 2 diet periods.
Results : High-density lipoprotein cholesterol concentration was significantly higher on the modified-fat diet than on the low-fat/low-carbohydrate diet. Arterial elasticity and concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were not significantly different on the 2 diets.
Applications/conclusions : There is no evidence to favor a diet high in monounsaturated fat over a low-fat/high-carbohydrate diet because of an effect on arterial elasticity. Other changes in diet may be needed to cause a beneficial effect on arterial elasticity.

Effects of resistance exercise and fortified milk on skeletal muscle mass, muscle size, and functional performance in middle-aged and older men: an 18-mo randomized controlled trial

Limited data have suggested that the consumption of fluid milk after resistance training (RT) may promote skeletal muscle hypertrophy. The aim of this study was to assess whether a milk-based nutritional supplement could enhance the effects of RT on muscle mass, size, strength, and function in middle-aged and older men. This was an 18-mo factorial design (randomized control trial) in which 180 healthy men aged 50–79 yr were allocated to the following groups: 1) exercise + fortified milk, 2) exercise, 3) fortified milk, or 4) control. Exercise consisted of progressive RT with weight-bearing impact exercise. Men assigned to the fortified milk consumed 400 ml/day of low-fat milk, providing an additional 836 kJ, 1000 mg calcium, 800 IU vitamin D3, and 13.2 g protein per day. Total body lean mass (LM) and fat mass (FM) (dual-energy X-ray absorptiometry), midfemur muscle cross-sectional area (CSA) (quantitative computed tomography), muscle strength, and physical function were assessed. After 18 mo, there was no significant exercise by fortified milk interaction for total body LM, muscle CSA, or any functional measure. However, main effect analyses revealed that exercise significantly improved muscle strength (∼20–52%, P < 0.001), LM (0.6 kg, P < 0.05), FM (−1.1 kg, P < 0.001), muscle CSA (1.8%, P < 0.001), and gait speed (11%, P < 0.05) relative to no exercise. There were no effects of the fortified milk on muscle size, strength, or function. In conclusion, the daily consumption of low-fat fortified milk does not enhance the effects of RT on skeletal muscle size, strength, or function in healthy middle-aged and older men with adequate energy and nutrient intakes.

Solubilization of selected free fatty acids in palm oil by biodegradable ethoxylated surfactants

The solubilization of three major components, viz., palmitic, oleic, and linoleic acids, in palm oil by ethoxylated surfactants was investigated. The results were analyzed in terms of the molecular properties of surfactants and free fatty acids (FFAs). It was found that the solubilities of these FFAs in various micellar solutions depend not only on their octanol−water partition coefficients (Kow), but also on their physicochemical properties. The study on the solubilization kinetics was conducted by choosing palmitic acid as a model solubilizate and Tergitol 15-S-7 as the model surfactant. A first-order film diffusion model, which accounts for the direct uptake of organic molecules at a solid surface into surfactant micelles, was adopted to analyze the effect of surfactant on dissolution of palmitic acid. It was observed that the presence of surfactant reduced the mass-transfer coefficient. Instead, the overall mass-transfer rate was enhanced because of the much higher driving force from the increased solubilization capacity.

Serum leptin levels are associated with bone mass in nonobese women

Both serum leptin and bone mineral density are positively correlated with body fat, generating the hypothesis that leptin may be a systemic and/or local regulator of bone mass. We investigated 214 healthy, nonobese Australian women aged 20-91 yr. Bone mineral content, projected bone area, and body fat mass were measured by dual energy x-ray absorptiometry and fasting serum leptin levels by RIA. Associations between bone mineral content (adjusted for age, body weight, body fat mass, and bone area) and the natural logarithm of serum leptin concentrations were analyzed by multiple regression techniques. There was a significant positive association at the lateral spine, two proximal femur sites (Ward's triangle and trochanter), and whole body (partial r² = 0.019 to 0.036; all P < 0.05). Similar trends were observed at the femoral neck and posterior-anterior-spine. With bone mineral density the dependent variable (adjusted for age, body weight, and body fat mass), the association with the natural logarithm of leptin remained significant at the lateral spine (partial r² = 0.030; P = 0.011), was of borderline significance at the proximal femur sites (partial r² = 0.012 to 0.017; P = 0.058 to 0.120), and was not significant at the other sites. Our results demonstrate an association between serum leptin levels and bone mass consistent with the hypothesis that circulating leptin may play a role in regulating bone mass.

Relationship of serum leptin to total and truncal body fat

1. In this study we investigated the relationship between serum leptin levels and body fat distribution in a random sample of women of widely ranging age and body mass index. Anthropometry and dual energy X-ray absorptiometry were used to measure body fat and its distribution.

2. Leptin levels (log transformed) were not significantly correlated with age, but were significantly positively correlated (P < 0.001) with most anthropometric measures except waist-to-hip circumference ratio. The strongest correlations were with total grams of body fat and percentage body fat (r = 0.68 and 0.76 respectively, P < 0.001). When corrected for percentage body fat the partial correlation coefficients for all other measures became non-significant. The correlation with truncal body fat fell significantly from 0.66 to - 0.05 after correction, but the partial correlation with total body fat remained significant (P < 0.005) when grams of truncal fat were controlled for (r = 0.21).

3. These results indicate that the relationship of serum leptin to percentage body fat is the strongest, and that truncal body fat, although the most metabolically active, does not appear to have an independent association with serum leptin.