Benefits of a year-long workplace weight loss program on cardiovascular risk factors. (Original Research).

Abstract

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)

Key words: workplace weight loss program, body weight, abdominal fat, blood pressure, blood lipids, lipoproteins, DXA 

Introduction

The economic cost of obesity associated with disease in Australia was estimated at $A840 million in 1992 to 1993 dollar terms (1) with few other morbid conditions incurring such high costs to the community. This cost could be considerably reduced with successful community weight loss programs in the workplace. Overweight and obesity are major risk factors for coronary heart disease (CHD) and are themselves responsible for other independent predictors of CHD such as hypertension, atherogenic dyslipidaemia and insulin resistance with glucose intolerance (2). Population levels of overweight and obesity among Australian men are disturbingly high with per capita body weight increasing at a rate of 1.7 kg per decade (3). By the beginning of the 1990s, one in six men had hypertension and a similar proportion had blood cholesterol concentrations of 6.5 mmol/L or more (4). With the marked rise in the number of people who have become overweight and obese in the last decade, the benefits from advances in the treatment o f cardiovascular health may be blunted.

Recent dietary trials (5,6) and meta-analysis of dietary interventions (7) and weight loss programs spanning two weeks to four years (8) have confirmed the earlier work of Keys et al. (9) that dietary modification can lessen the risk of CHD. Increased physical activity has been associated with reduced risk for cardiovascular disease (10). Aerobic exercise has been found to reduce blood pressure with weight loss (11) and without it (12) and to improve insulin sensitivity in Type 2 diabetes (13). Change in the lipoprotein profile (lowered triglycerides, total cholesterol and LDL cholesterol (LDL) concentrations with increases in HDL cholesterol (HDL)), is also described as a benefit of aerobic exercise (2,14).

Weight loss benefits have been described for hypertension (15), hyperinsulinaemia (16)and for lipidaemia (17) but the overall benefits to cardiovascular risk factors of a long-term Australian workplace weight loss program have not been reported. The aim of this study was to assess the health benefits (such as changes in blood pressure, insulin sensitivity, blood lipids and lipoproteins) associated with changes in body composition accompanying a year-long, self-directed weight loss program effected by reduction of dietary fat and increased exercise.

Methods

Subjects

Fifty-eight middle-aged, overweight men (mean [+ or -] SD: 43.4 [+ or -] 5.7 years, BMI 29.0 [+ or -] 2.6 kg/[m.sup.2]) of an original 66 who were recruited to participate in a year-long weight loss study completed the program. The subjects, employees of a national business corporation, previously screened as overweight (BMI 26 to 35) were accepted into the study following the completion of a satisfactory medical and cardiovascular fitness test. Using a system of random numbers (18) the men were randomly assigned into three groups for 12 months: diet (n = 18), exercise (n = 21) and control (n = 19). Sixteen of the original control subjects volunteered to follow a combined diet and exercise (n = 16) program for a subsequent 12 months.

The study was approved by both the Board of Medical Research and the Ethics Committee on Research at the Royal Melbourne Hospital. Informed written consent was obtained from each subject.

Interventions

Dietary intervention was a low-fat diet (25% of dietary energy), using the National Heart Foundation booklet, The Weight Loss Guide (19), the intervention being personalised according to the subject's usual dietary pattern. Energy intake and nutritional adequacy were assessed from analysis of 24-hour food recalls recorded monthly, confirmed in three-day food diaries at six and 12 months (Diet/l Software, Xyris Software, Brisbane, Queensland, version 3, 2000).

Exercise subjects selected their own intervention regimen to be undertaken in their leisure time. A minimum of three sessions of 30 minutes per week above their pre-study exercise level that achieved 65 to 75% of maximum heart rate was instituted. Personal heart rate target zones were determined by an initial heart rate recording over 33 hours of normal activity which included the selected exercise (Polar Sports Tester PE4000, Polar Electro Oy, Kempele, Finland). Of the 21 exercise subjects, 11 walked, four jogged (two alternated with swimming), three attended a gymnasium and three rode an exercise bike. The 16 diet and exercise subjects used cycling (three), walking (nine), jogging (three) and home gymnasium equipment (one). Participation rates were between three to seven sessions per week.

Control subjects were instructed to maintain their pre-study dietary and activity patterns. These were monitored at monthly measurement sessions similar to those of the intervention subjects.

Energy expenditure was estimated using an index of physical activity (PAL), assessed from 24-hour activity logs recorded monthly, confirmed in pedometer diaries and three-day activity diaries, expressed as a multiple of personal basal metabolic rate (BMR), according to Warwick (20). Energy balance was estimated monthly for all subjects as the difference between energy expenditure and intake.

Procedures

Monthly interviews for measurement of weight and blood pressure and monitoring of diet, exercise or weight maintenance were held prior to commencement of work at workplace locations. Blood pressure was measured after sitting for five minutes, and the mean of second and third measurements recorded (Dinamap autorecorder 8101, Johnson and Johnson, North Ryde, NSW). The data from eight subjects (three diet, three exercise, two control and one diet and exercise) on blood pressure medication were analysed separately. Blood, sampled at baseline and study's end, was analysed for serum insulin, lipid and lipoprotein concentrations. Lipid and lipoprotein analyses were undertaken in the Chemical Pathology Department of St Vincent's Hospital, Melbourne. Baseline analyses were unavailable for ten diet, six exercise and two control subjects as randomisation into intervention occurred before on-site facilities to collect blood samples were available to us. Post-intervention analyses were available for all participants but a re used here only for those with baseline data. Serum insulin was analysed in the Biochemistry and Endocrinology departments of Royal Melbourne Hospital. Only data from subjects considered to be in the fasting state by assessment of blood glucose concentrations below 7.0 mmol/L were used in the statistical analysis. Body composition was measured using an Hologic QDR W/1000 whole body X-ray absorptiometer in the Bone and Mineral Service of the Royal Melbourne Hospital. This technique (DXA) has the unique ability to produce precise regional measurements of body composition (21) and has previously identified progressive total, central and peripheral changes in fat and lean tissue accompanying weight change (22). Pre- and post-intervention measures of energy balance, body composition, blood pressure, serum insulin, lipid and lipoprotein analyses were assessed.

Statistical analysis

The SPSSx program (Norusis/SPSS Inc., Chicago, IL, release 4.0 for VAX/VMS, 1990) was used to determine: difference between groups, using analysis of variance (ANOVA) and the Scheffe post hoc test; within-group pre- and post-test differences using Students' paired t-tests; significant association between dependent variables, according to univariate linear regression and Pearson's correlation coefficient, and specific predictors using multiple stepwise regression. An alpha level of P < 0.05 was selected to determine statistical significance.

Results

Fifty-eight of the original 66 men recruited completed the year-long program. Two subjects withdrew before randomisation. Of the six subjects who did not complete the 12 months of the study, two (one control, one diet) withdrew through ill-health unrelated to the study, three diet subjects withdrew for personal, domestic reasons and one exercise subject through workplace difficulties.

Energy balance

The estimates of PAL, energy expenditure and energy balance are reported with the analyses of energy intake and the percentage dietary energy from fat intake in Table 1.

There were significant decreases in energy intake in the diet and in the diet and exercise groups, arising from a decrease in dietary fat, but not in the exercise nor control groups. Pre- and post-intervention diets of all participants were subjected to full nutritional analysis but no individual nutrient other than dietary fat was identified in association with the parameters of this study. With intervention energy expenditure estimates were significantly greater in exercising subjects only. No change in energy expenditure occurred in the diet or control groups. Energy balance for each intervention was negative, significantly different from control in the diet and the diet and exercise groups (P < 0.05), but not from each other (ANOVA, P = 0.06). When data from all interventions were compared with baseline data, energy intake, percentage dietary energy from fat, energy expenditure, PAL and energy balance were each significantly different.

Body composition

Changes in body weight, fat mass and lean mass are reported in Table 2. Weight loss with interventions produced changes in anthropometric characteristics, which differed from control. Baseline similarity in body weight and fat mass between groups changed with intervention and both were significantly different from control in the diet, exercise and diet and exercise groups and in all interventions together. Change in abdominal fat (-26.8 [+ or -] 3.6% in diet; -16.6 [+ or -] 4.5% in exercise; -21.0 [+ or -] 4.7% in diet and exercise; -21.5 [+ or -] 2.5% in all interventions) exceeded that in peripheral fat, both of which were greater with the dietary interventions. Loss of lean mass occurred with diet-induced weight loss and with all interventions together, loss of fat mass was significant in all intervention groups.

Risk factors

Table 3 shows cardiovascular risk factors measured in this study, blood pressure, serum insulin and blood lipids and lipoproteins concentrations at baseline and after the yearlong intervention.

Blood pressure

Although systolic (SBP) and diastolic (DBP) blood pressure did not show significant falls with any one intervention group there was significant change when all interventions were analysed together (SBP -3.3 [+ or -] 1.7%, DBP -4.8 [+ or -] 1.3%). The range of response was wide (overall mean loss of 4.6 mm Hg SBP, range -26.0 to +15.0 mm Hg, -4.0 mm Hg DBP, range - 18.0 to [+ or -] 11.0 mm Hg).

With pooled data from all groups, multivariate regression analysis identified baseline blood pressure as a significant predictor of change in SBP and DBP regardless of the method of weight loss: percentage change in SBP = 0.3 x baseline SBP -- 32; ([R.sup.2] = 0.25, b = 0.50, P < 0.0001), predicted that weight loss would induce a 4% (5 mm Hg) decrease in SBP in a man with 120 mm Hg initial SBP or a 16% (26 mm Hg) fall in a man whose pre-weight loss SBP was 160 mm Hg.

Multivariate regression analysis similarly identified abdominal fat loss as a predictor of change in both SBP and DBP with weight loss. The equation: percentage change in SBP = 0.l5 x % change in abdominal fat -- 0.6; ([R.sup.2] = 0.15, b = 0.39, P < 0.01) predicted that a modest 20% loss of abdominal fat would be accompanied by a percentage fall in SBP of 2.4 [+ or -] 0.05%. Similarly, percentage change in DBP = 0.17 x % change in abdominal fat + 2.0; ([R.sup.2] = 0.09, b = 0.29, P < 0.05) predicted that 20% loss of abdominal fat would be accompanied by a percentage decrease of 5.4 [+ or -] 0.07% in DBP. Figure 1 shows the linear relationship between change in SBP and change in abdominal fat (r = 0.38, P < 0.01).

Insulin

Table 3 shows fasting serum insulin concentrations at one year were significantly lower from baseline with exercise intervention (33.6 to 38.0%) and with all interventions together, (-31.0%). There was a correlation between insulin and abdominal fat before and after intervention (r = 0.37 and r = 0.30, respectively, both P < 0.05). The relationship is shown in Figure 2, with a greater fall in fasting serum insulin concentrations in those who lost most abdominal fat (P < 0.001).

Lipids and lipoproteins

Baseline and one-year total cholesterol, LDL and HDL and triglyceride concentrations are reported in Table 3. There was a fall in total and LDL cholesterol in diet and exercise and a fall in triglycerides in the exercise groups (exercise, diet and exercise). These changes were different from the controls for triglycerides only. The post-intervention trend to lower values in total and LDL cholesterol and to higher values in HDL in all groups including control effected significant improvement in the LDL/HDL ratio in all groups. Significant inverse correlation was identified between the change in HDL and change in body weight (r = -0.51, P < 0.001), fat mass (r = -0.50, P < 0.0001) and abdominal fat (r = -0.48, P < 0.01). Multiple regression analysis with pooled data from all interventions indicated loss of abdominal fat as the strongest predictor of change in HDL. Percentage change HDL = -2.2 - 0.48 x % abdominal fat loss ([R.sup.2] = 0.17, P = 0.002). Figure 3 shows the linear relationship between increase in HDL and loss of abdominal fat.

Discussion

This is one of the few long-term studies that has emphasised gradual weight loss through moderate lifestyle change in diet and exercise. Its findings have demonstrated that weight loss through a long-term change in energy balance using ad libitum low-fat dietary modification and/or moderate self-directed exercise results in significant health benefits. The high retention rate (overall 88%, which did not differ significantly between groups) reflected the effectiveness of a program conducted in the workplace. The convenience of clinical measurements being performed on-site and the influence of peer-group support for maintaining lifestyle change over one year assisted compliance. Equivalent benefit to compliance has been described in a recent Swedish workplace study that achieved improvements in cardiovascular risk factors (23) and in a similar approach towards lifestyle change over 12 months in a clinical setting that relied on encouragement from general medical practitioners (24).

Although the power of this study to detect changes in blood lipids was limited and did not allow us to assess the difference in cardiovascular risk factors effected by diet or exercise strategies, it did confirm that weight loss accompanying a combination of diet and exercise reduced total cholesterol concentration by 4.2% and triglycerides by 27.6%, and when all interventions were analysed together, a fall of 3.9% in LDL with a 10% rise in HDL. The National Nutrition Survey in 1995 found that 45% of middle-aged Australian men are overweight and 25% are obese (3), providing serious risk of CHD to this proportion of the population (4). Lifestyle change in diet and exercise may result in only a modest weight loss, yet a decrease in BMI from 28 to 27 kg/[m.sup.2] has been estimated to halve the relative risk of cardiovascular mortality in North American men and women (25). A meta-analysis of the USA's National Cholesterol Education Program found that every one kilogram weight loss consequent to dietary change ac hieved a fall in triglycerides of 0.011 mmol/L and a rise in HDL of 0.011 mmol/L while decrements in total and LDL cholesterol concentrations accompanied lower dietary fat intake (7).

An increase in HDL has been found to reduce mortality in CHD independently of total cholesterol concentration (26). Our findings of an increase of 0.03 mmol/L in HDL per kilogram of abdominal fat loss over the length of the study confirms reports from an array of international studies of the strong inverse association of HDL with central adiposity (27,33-35). From the meta-analysis of 70 studies Dattilo and Kris-Etherton predicted 0.009 mmol/L increase in HDL per kilogram weight loss in subjects at stabilised reduced weight (8). As abdominal obesity is now recognised as a major risk factor for CHD, the ability to predict the degree of elevation of the atherogenic-protecting HDL through loss of abdominal fat induced by modest lifestyle change is particularly useful in reducing CHD risk (26). Previous studies in men (38), and in women (39) used waist and hip circumferences to identify central adiposity as a predictor of CHD risk. As Walton and colleagues have previously described in their study of the associati on of dyslipidaemia with android fat distribution, we found that the DXA technique provided a precise measurement of abdominal fat (34).

However, it should be noted that changing to an excessively low fat diet to achieve loss of abdominal fat is contraindicated. Raised carbohydrate intakes have been found to produce a counter effect with HDL concentration falling and triglyceride concentrations rising (27-29). This compensatory change in higher carbohydrate intake to the lower dietary fat in our diet group may account for the failure of triglycerides to fall and the loss of abdominal fat to be effective in inducing significant HDL increments.

An additional achievement from our workplace program was the beneficial effect on blood pressure with a decline of 3.3 [+ or -] 1.7% in systolic and of 4.8 [+ or -] 1.3% in diastolic blood pressure when all interventions were analysed together. The relationship between blood pressure and weight change has been described previously (30) with emphasis more recently placed on gradual and moderate weight loss of 5% to 10% to normalise blood pressure without even reaching ideal weight (15). Although physical activity, especially regular aerobic exercise, has been found to reduce blood pressure in normotensive healthy young men (11) the change in blood pressure in the exercisers in this study was not correlated with change in energy expenditure but showed the greatest association with loss of abdominal fat, so that a modest loss of total body weight, resulting in loss of abdominal fat in exercising subjects, was associated with a reduction in blood pressure.

The loss of abdominal fat also improved insulin sensitivity. The relationship of both pre- and post-intervention serum insulin concentration with pre- and post-intervention abdominal fat was an expected confirmation of the association of centrally stored fat with hyperinsulinaemia (31). It is recognised that hyperinsulinaemia and hypertension are each components of the multiple metabolic syndrome that predisposes towards CHD. Abdominal fat is not dependent on increased insulin concentrations or on high blood pressure: the relationship is one of association and not causality. Loss of abdominal fat does not depend upon decrease in insulin, nor does it depend upon fall in blood pressure, yet both are predicted to accompany loss of abdominal fat, supporting the concept that hypertension, dyslipidaemia and insulin resistance are each 'spokes on the wheel', with central obesity as the postulated hub, the wheel being the clustering of CHD risk factors that comprise 'Syndrome X' (32).

The different interventions were accompanied by different changes in body composition. Where exercisers were able to achieve negative energy balance similar to that of dieters a similar loss of abdominal fat has been described (36). Greater energy expenditure, through higher levels of physical activity, would be required to achieve equivalent change in body composition (37). In our study self-directed exercise did not achieve equivalent negative energy balance or the same degree of weight loss. However, abdominal fat loss represented a greater proportion of total fat loss enabling concomitant elevation of HDL accompanied by the improved insulin sensitivity in both exercising groups.

Conclusion

This study demonstrated that a modest 5% weight loss, accompanied by a 20% loss of abdominal fat, consequent to moderate lifestyle change, achieved improvements in blood pressure, insulin sensitivity and the lipid profile of middle-aged overweight men. The program had a high retention rate and was achieved without severe dietary restriction, without participation in a supervised, structured exercise program and without great cost or medical supervision. The success of the program benefited from its workplace location to show that long-term change in lifestyle habits involving ad libitum low-fat dietary change and/or moderate self-directed exercise was sufficient to halt the progress of the atherogenic lipid pattern. As no one strategy showed significant benefit over the other, we recommend workplace education in the benefits of a moderate low-fat dietary pattern (30% dietary energy from fat) within a lifestyle involving regular exercise (at least four times per week) to reduce abdominal fat and lower risk of cardiovascular disease.

Table 1

Energy intake, energy expenditure and energy balance at baseline and
after 12 months intervention


                                   Control
                                   n = 19

Energy intake (MJ/day)

Baseline (a)                   9.3 [+ or -] 1.9
12 months (a)                  9.7 [+ or -] 1.8
% Change (b)                  +5.5 [+ or -] 4.7

Percentage energy as fat (%)

Baseline (a)                  38.5 [+ or -] 6.0
12 months (a)                 38.9 [+ or -] 5.9
% Change (b)                  +1.7 [+ or -] 2.6

Energy expended (MJ/day)

Baseline (a)                  10.6 [+ or -] 1.2
12 months (a)                 11.3 [+ or -] 1.4
% Change (b)                  +6.5 [+ or -] 1.5

Physical activity level

Baseline (a)                   1.3 [+ or -] 0.1
12 months (a)                  1.4 [+ or -] 0.1
% Change (b)                  +6.4 [+ or -] 1.7

Energy balance (MJ)

Baseline (a)                  -1.3 [+ or -] 1.8
12 months (b)                 -0.6 [+ or -] 2.3

                                     Diet
                                    n = 18

Energy intake (MJ/day)

Baseline (a)                   10.9 [+ or -] 2.4
12 months (a)                   7.5 [+ or -] 2.2 (e, f)
% Change (b)                  -30.4 [+ or -] 3.8 (f)

Percentage energy as fat (%)

Baseline (a)                   38.2 [+ or -] 5.8
12 months (a)                  25.4 [+ or -] 6.6 (e,f)
% Change (b)                  -32.0 [+ or -] 4.8 (f)

Energy expended (MJ/day)

Baseline (a)                   10.1 [+ or -] 0.6
12 months (a)                  10.8 [+ or -] 1.1
% Change (b)                   +5.9 [+ or -] 1.9

Physical activity level

Baseline (a)                    1.3 [+ or -] 0.2
12 months (a)                   1.3 [+ or -] 0.1
% Change (b)                   +3.4 [+ or -] 1.2

Energy balance (MJ)

Baseline (a)                    0.8 [+ or -] 0.8
12 months (b)                  -3.3 [+ or -] 1.8 (d)

                                     Exercise
                                      n = 21

Energy intake (MJ/day)

Baseline (a)                    10.4 [+ or -] 1.6
12 months (a)                   10.8 [+ or -] 2.3
% Change (b)                    +3.1 [+ or -] 2.7

Percentage energy as fat (%)

Baseline (a)                    38.9 [+ or -] 6.8
12 months (a)                   38.6 [+ or -] 6.1
% Change (b)                    +1.0 [+ or -] 3.8

Energy expended (MJ/day)

Baseline (a)                    10.8 [+ or -] 1.3
12 months (a)                   12.4 [+ or -] 1.7 (e)
% Change (b)                   +14.6 [+ or -] 2.0 (g)

Physical activity level

Baseline (a)                     1.3 [+ or -] 0.2
12 months (a)                    1.6 [+ or -] 0.2 (c)
% Change (b)                   +15.6 [+ or -] 2.2 (f)

Energy balance (MJ)

Baseline (a)                     0.4 [+ or -] 0.7
12 months (b)                   -1.6 [+ or -] 2.9 (g)

                                 Diet + Exercise
                                      n = 16

Energy intake (MJ/day)

Baseline (a)                   10.0 [+ or -] 1.4
12 months (a)                   7.6 [+ or -] 1.5 (c)
% Change (b)                  -23.0 [+ or -] 3.9 (f)

Percentage energy as fat (%)

Baseline (a)                   38.8 [+ or -] 5.8
12 months (a)                  31.2 [+ or -] 7.7 (d)
% Change (b)                  -19.8 [+ or -] 5.1 (f)

Energy expended (MJ/day)

Baseline (a)                   11.3 [+ or -] 1.4
12 months (a)                  12.8 [+ or -] 1.6 (c)
% Change (b)                  +13.0 [+ or -] 2.0

Physical activity level

Baseline (a)                    1.4 [+ or -] 0.1
12 months (a)                   1.6 [+ or -] 0.2 (c)
% Change (b)                   +7.2 [+ or -] 2.6 (f)

Energy balance (MJ)

Baseline (a)                   -1.3 [+ or -] 1.8
12 months (b)                  -4.8 [+ or -] 2.0 (c)

                                All interventions
                                     n = 55

Energy intake (MJ/day)

Baseline (a)                   10.4 [+ or -] 2.0
12 months (a)                   8.9 [+ or -] 2.6 (e)
% Change (b)                  -16.1 [+ or -] 2.8

Percentage energy as fat (%)

Baseline (a)                   38.7 [+ or -] 6.1
12 months (a)                  31.5 [+ or -] 8.5 (e)
% Change (b)                  -16.8 [+ or -] 3.4

Energy expended (MJ/day)

Baseline (a)                   10.4 [+ or -] 1.2
12 months (a)                  11.8 [+ or -] 1.7 (e)
% Change (b)                  +11.5 [+ or -] 1.4

Physical activity level

Baseline (a)                    1.3 [+ or -] 0.2
12 months (a)                   1.5 [+ or -] 0.2 (e)
% Change (b)                   +9.2 [+ or -] 1.4

Energy balance (MJ)

Baseline (a)                   -0.2 [+ or -] 2.1
12 months (b)                  -3.0 [+ or -] 2.7 (e)

(a) mean [+ or -] SD

(b) mean [+ or -] SEM

(c) significantly different from baseline P < 0.05 (t-test)

(d) significantly different from baseline P <0.01 (t-test)

(e) significantly different from baseline P < 0.0001 (t-test)

(f) significant difference between groups P < 0.05 (ANOVA, Scheffe post
hoc)

(g) significant difference of exercise from control, diet and diet and
exercise P < 0.05 (ANOVA)
Table 2

Total and regional body compostion at baseline and the change after 12
months intervention

                               Control               Diet
                                n = 19              n = 18

Body weight (kg)

 Baseline (a)             87.8 [+ or -] 10.9  87.8 [+ or -] 10.5
 Change at 12 months (a)    0.3 [+ or -] 2.4   -6.4 [+ or -] 3.3 (e)
 % Change (b)              +1.3 [+ or -] 0.6   -7.2 [+ or -] 0.9 (e)

Total fat (kg)

 Baseline (a)              19.2 [+ or -] 3.5   19.0 [+ or -] 4.2
 Change at 12 months (a)   -0.1 [+ or -] 1.3   -3.8 [+ or -] 2.1 (e)
 % Change (b)              -0.4 [+ or -] 1.6  -19.4 [+ or -] 2.3 (d,e)

Abdominal fat (kg)

 Baseline (a)              3.46 [+ or -] 1.1   3.91 [+ or -] 1.3
 Change at 12 months (a)  +0.07 [+ or -] 0.4   -1.0 [+ or -] 0.6 (e)
 % Change (b)              +0.1 [+ or -] 3.2  -26.8 [+ or -] 3.6 (d,e)

Peripheral fat (kg)

 Baseline (a)               9.2 [+ or -] 1.6    8.7 [+ or -] 1.9
 Change at 12 months (a)  -0.01 [+ or -] 0.6   -1.5 [+ or -] 0.9 (e)
 % Change (b)             -0.07 [+ or -] 1.4  -17.0 [+ or -] 2.1 (d,e)

Total lean (kg)

 Baseline (a)              65.6 [+ or -] 7.7   65.9 [+ or -] 7.3
 Change at 12 months (a)   +0.1 [+ or -] 1.3   -2.6 [+ or -] 1.4 (e)
 % Change (b)              +0.2 [+ or -] 1.9   -3.9 [+ or -] 2.1 (d,e)

                               Exercise
                                n = 21

Body weight (kg)

 Baseline (a)             88.1 [+ or -] 10.1
 Change at 12 months (a)   -2.6 [+ or -] 3.0 (e)
 % Change (b)              -3.0 [+ or -] 0.8 (e)

Total fat (kg)

 Baseline (a)              18.3 [+ or -] 4.5
 Change at 12 months (a)   -1.9 [+ or -] 1.9
 % Change (b)             -11.0 [+ or -] 2.7 (d,e)

Abdominal fat (kg)

 Baseline (a)              3.48 [+ or -] 1.5
 Change at 12 months (a)   -0.5 [+ or -] 0.5
 % Change (b)             -16.6 [+ or -] 4.5 (d,e)

Peripheral fat (kg)

 Baseline (a)               8.6 [+ or -] 2.5
 Change at 12 months (a)   -0.8 [+ or -] 0.9
 % Change (b)             -10.4 [+ or -] 2.4 (c,e)

Total lean (kg)

 Baseline (a)              66.0 [+ or -] 7.8
 Change at 12 months (a)   -0.7 [+ or -] 1.6
 % Change (b)              -1.0 [+ or -] 2.5

                           Diet + Exercise
                                n = 16

Body weight (kg)

 Baseline (a)             88.2 [+ or -] 10.8
 Change at 12 months (a)   -4.5 [+ or -] 3.5 (e)
 % Change (b)              -5.1 [+ or -] 1.0 (e)

Total fat (kg)

 Baseline (a)              19.3 [+ or -] 4.0
 Change at 12 months (a)   -3.1 [+ or -] 2.2 (e)
 % Change (b)             -15.9 [+ or -] 3.0 (c,e)

Abdominal fat (kg)

 Baseline (a)              3.53 [+ or -] 1.0
 Change at 12 months (a)   -1.0 [+ or -] 0.6 (e)
 % Change (b)             -21.0 [+ or -] 4.7 (d,e)

Peripheral fat (kg)

 Baseline (a)               9.2 [+ or -] 1.9
 Change at 12 months (a)   -1.3 [+ or -] 1.0
 % Change (b)             -15.0 [+ or -] 2.5 (c,e)

Total lean (kg)

 Baseline (a)              66.0 [+ or -] 7.1
 Change at 12 months (a)   -1.4 [+ or -] 1.7
 % Change (b)              -2.1 [+ or -] 0.7 (e)

                          All interventions
                                n = 55

Body weight (kg)

 Baseline (a)              88.2 [+ or -] 9.3
 Change at 12 months (a)   -4.2 [+ or -] 3.6 (d)
 % Change (b)              -4.9 [+ or -] 0.9

Total fat (kg)

 Baseline (a)              19.2 [+ or -] 4.2
 Change at 12 months (a)   -2.8 [+ or -] 2.2 (d)
 % Change (b)             -15.0 [+ or -] 1.6

Abdominal fat (kg)

 Baseline (a)              3.63 [+ or -] 1.3
 Change at 12 months (a)  -0.73 [+ or -] 0.6 (d)
 % Change (b)             -21.5 [+ or -] 2.5

Peripheral fat (kg)

 Baseline (a)               8.8 [+ or -] 2.0
 Change at 12 months (a)   -1.1 [+ or -] 1.0 (d)
 % Change (b)             -13.8 [+ or -] 1.4

Total lean (kg)

 Baseline (a)              66.2 [+ or -] 7.2
 Change at 12 months (a)   -1.5 [+ or -] 1.7 (d)
 % Change (b)              -2.2 [+ or -] 1.1

(a) mean [+ or -] SD

(b) mean [+ or -] SEM

(c) significantly different from control P < 0.01 (t-test)

(d) significantly different from control P < 0.001 (t-test)

(e) significant difference between groups P < 0.05 (ANOVA, Scheffe post
hoc)
Table 3

Cardiovascular risk factors at baseline and after 12 months intervention

                                                      Control
                                                       n = 19

Systolic blood pressure (a) (mm Hg)                    n = 17

 Baseline (b)                              126.8 [+ or -] 9.2
 12 months (b)                             125.4 [+ or -] 8.1
 % Change (c)                               -0.8 [+ or -] 1.5

Diastolic blood pressure (a)
 (mm Hg)                                               n = 17

 Baseline (b)                               78.0 [+ or -] 9.2
 12 months (b)                              74.5 [+ or -] 9.6
 % Change (c)                               -4.3 [+ or -] 1.7

Insulin (a) (mU/L)                                     n = 12

 Baseline (b)                               10.3 [+ or -] 4.7
 12 months (b)                               9.2 [+ or -] 3.9
 % Change (c)                             -10.6 [+ or -] 15.0

Total cholesterol (a) (mmol/L)                         n = 17

 Baseline (b)                                5.1 [+ or -] 1.4
 12 months (b)                               5.3 [+ or -] 0.7
 % Change (c)                               -1.4 [+ or -] 3.2

LDL cholesterol (a) (mmol/L)                           n = 17

 Baseline (b)                              3.74 [+ or -] 1.21
 12 months (b)                             3.28 [+ or -] 0.51
 % Change (c)                               -3.1 [+ or -] 4.7

HDL cholesterol (a) (mmol/L)                           n = 17

 Baseline (b)                              1.21 [+ or -] 0.27
 12 months (b)                             1.23 [+ or -] 0.30
 % Change (c)                               +1.6 [+ or -] 3.3

LDL:HDL ratio (a)                                      n = 17

Baseline (b)                                 3.0 [+ or -] 0.8
12 months (b)                            2.7 [+ or -] 1.0 (f)
% Change (c)                                -9.9 [+ or -] 6.1

Triglycerides (a) (mmol/L)                             n = 17

Baseline (b)                               1.76 [+ or -] 1.46
12 months (b)                              1.64 [+ or -] 0.94
% Change (c)                               -6.8 [+ or -] 12.8

                                                         Diet
                                                       n = 18

Systolic blood pressure (a) (mm Hg)                    n = 15

 Baseline (b)                              131.1 [+ or -] 9.5
 12 months (b)                             125.5 [+ or -] 7.6
 % Change (c)                               -4.0 [+ or -] 1.0

Diastolic blood pressure (a)
 (mm Hg)                                               n = 15

 Baseline (b)                               79.6 [+ or -] 9.8
 12 months (b)                              76.3 [+ or -] 5.9
 % Change (c)                               -3.7 [+ or -] 1.7

Insulin (a) (mU/L)                                     n = 12

 Baseline (b)                               11.7 [+ or -] 5.8
 12 months (b)                               9.6 [+ or -] 3.8
 % Change (c)                             -15.6 [+ or -] 18.2

Total cholesterol (a) (mmol/L)                          n = 8

 Baseline (b)                                6.3 [+ or -] 1.3
 12 months (b)                               5.5 [+ or -] 1.3
 % Change (c)                               -3.1 [+ or -] 2.4

LDL cholesterol (a) (mmol/L)                            n = 8

 Baseline (b)                              4.07 [+ or -] 1.31
 12 months (b)                             3.41 [+ or -] 1.00
 % Change (c)                               -4.8 [+ or -] 4.6

HDL cholesterol (a) (mmol/L)                            n = 8

 Baseline (b)                              1.09 [+ or -] 0.26
 12 months (b)                             1.12 [+ or -] 0.34
 % Change (c)                               +2.1 [+ or -] 4.9

LDL:HDL ratio (a)                                       n = 8

Baseline (b)                                 3.6 [+ or -] 1.0
12 months (b)                            3.3 [+ or -] 1.4 (f)
% Change (c)                               -10.9 [+ or -] 5.4

Triglycerides (a) (mmol/L)                              n = 8

Baseline (b)                               2.49 [+ or -] 2.13
12 months (b)                              2.75 [+ or -] 3.31
% Change (c)                               +5.6 [+ or -] 26.6

                                                       Exercise
                                                         n = 21

Systolic blood pressure (a) (mm Hg)                      n = 18

 Baseline (b)                               132.5 [+ or -] 13.2
 12 months (b)                              128.9 [+ or -] 12.1
 % Change (c)                                 -2.5 [+ or -] 1.3

Diastolic blood pressure (a)
 (mm Hg)                                                 n = 18

 Baseline (b)                                 79.6 [+ or -] 9.6
 12 months (b)                                76.1 [+ or -] 8.1
 % Change (c)                                 -4.4 [+ or -] 2.4

Insulin (a) (mU/L)                                       n = 17

 Baseline (b)                                 12.9 [+ or -] 7.3
 12 months (b)                             8.1 [+ or -] 4.3 (e)
 % Change (c)                               -38.0 [+ or -] 28.3

Total cholesterol (a) (mmol/L)                           n = 15

 Baseline (b)                                  6.1 [+ or -] 1.2
 12 months (b)                                 5.9 [+ or -] 1.1
 % Change (c)                                 -1.5 [+ or -] 2.6

LDL cholesterol (a) (mmol/L)                             n = 15

 Baseline (b)                                4.05 [+ or -] 1.19
 12 months (b)                               3.70 [+ or -] 1.02
 % Change (c)                                 -2.0 [+ or -] 6.7

HDL cholesterol (a) (mmol/L)                             n = 15

 Baseline (b)                                1.24 [+ or -] 0.28
 12 months (b)                               1.25 [+ or -] 0.29
 % Change (c)                                 +2.1 [+ or -] 3.6

LDL:HDL ratio (a)                                        n = 15

Baseline (b)                                   3.3 [+ or -] 1.0
12 months (b)                              3.1 [+ or -] 1.1 (f)
% Change (c)                                  -6.4 [+ or -] 6.6

Triglycerides (a) (mmol/L)                               n = 15

Baseline (b)                                 2.57 [+ or -] 1.60
12 months (b)                            1.85 [+ or -] 1.22 (d)
% Change (c)                             -19.3 [+ or -] 8.1 (g)

                                                Diet + Exercise
                                                         n = 16

Systolic blood pressure (a) (mm Hg)                      n = 15

 Baseline (b)                                122.5 [+ or -] 8.1
 12 months (b)                               122.3 [+ or -] 6.9
 % Change (c)                                 -2.9 [+ or -] 1.0

Diastolic blood pressure (a)
 (mm Hg)                                                 n = 15

 Baseline (b)                                 74.5 [+ or -] 9.6
 12 months (b)                                72.8 [+ or -] 8.3
 % Change (c)                                 -2.1 [+ or -] 2.0

Insulin (a) (mU/L)                                       n = 11

 Baseline (b)                                  8.3 [+ or -] 2.8
 12 months (b)                             5.5 [+ or -] 2.9 (e)
 % Change (c)                               -33.6 [+ or -] 23.1

Total cholesterol (a) (mmol/L)                           n = 16

 Baseline (b)                                  5.5 [+ or -] 0.8
 12 months (b)                             5.2 [+ or -] 1.0 (d)
 % Change (c)                                 -4.2 [+ or -] 2.0

LDL cholesterol (a) (mmol/L)                             n = 16

 Baseline (b)                                3.74 [+ or -] 0.56
 12 months (b)                           3.49 [+ or -] 0.78 (d)
 % Change (c)                                 -4.8 [+ or -] 4.6

HDL cholesterol (a) (mmol/L)                             n = 16

 Baseline (b)                                1.21 [+ or -] 0.29
 12 months (b)                               1.24 [+ or -] 0.55
 % Change (c)                                 +2.5 [+ or -] 4.6

LDL:HDL ratio (a)                                        n = 16

Baseline (b)                                   3.0 [+ or -] 1.1
12 months (b)                              2.8 [+ or -] 1.2 (f)
% Change (c)                                  -5.7 [+ or -] 6.6

Triglycerides (a) (mmol/L)                               n = 16

Baseline (b)                                 1.83 [+ or -] 1.17
12 months (b)                            1.18 [+ or -] 0.46 (d)
% Change (c)                             -27.6 [+ or -] 2.0 (g)

                                            All interventions
                                                       n = 55

Systolic blood pressure (a) (mm Hg)                    n = 48

 Baseline (b)                             130.5 [+ or -] 11.2
 12 months (b)                         125.9 [+ or -] 9.5 (f)
 % Change (c)                               -3.3 [+ or -] 1.7

Diastolic blood pressure (a)
 (mm Hg)                                               n = 48

 Baseline (b)                               79.2 [+ or -] 9.5
 12 months (b)                          75.2 [+ or -] 9.7 (f)
 % Change (c)                               -4.8 [+ or -] 1.3

Insulin (a) (mU/L)                                     n = 40

 Baseline (b)                               10.2 [+ or -] 5.0
 12 months (b)                           6.2 [+ or -] 2.3 (e)
 % Change (c)                              -31.0 [+ or -] 5.6

Total cholesterol (a) (mmol/L)                         n = 39

 Baseline (b)                                5.6 [+ or -] 1.1
 12 months (b)                               5.7 [+ or -] 1.1
 % Change (c)                               -3.7 [+ or -] 3.2

LDL cholesterol (a) (mmol/L)                           n = 39

 Baseline (b)                                3.7 [+ or -] 1.0
 12 months (b)                           3.5 [+ or -] 0.9 (e)
 % Change (c)                               -3.9 [+ or -] 2.8

HDL cholesterol (a) (mmol/L)                           n = 39

 Baseline (b)                              1.12 [+ or -] 0.27
 12 months (b)                         1.23 [+ or -] 0.40 (e)
 % Change (c)                              +1.00 [+ or -] 3.8

LDL:HDL ratio (a)                                      n = 39

Baseline (b)                                 3.4 [+ or -] 1.0
12 months (b)                            3.1 [+ or -] 1.2 (f)
% Change (c)                                -8.9 [+ or -] 3.5

Triglycerides (a) (mmol/L)                             n = 39

Baseline (b)                                 2.1 [+ or -] 1.5
12 months (b)                                2.0 [+ or -] 2.1
% Change (c)                               -25.7 [+ or -] 4.2

(a) data not available for some subjects

(b) mean [+ or -] SD

(c) mean [+ or -] SEM

(d) significantly different from baseline P < 0.05 (t-test)

(e) significantly different from baseline P < 0.001 (t-test)

(f) significantly different from
 baseline P < 0.001 (t-test)

(g) significanlty different from controls P < 0.05 (ANOVA; Scheffe post
hoc)

Acknowledgments

The following research grants:

The University of Melbourne Special Initiatives Grant; The Victorian Health Promotion Foundation; The William Buckland Foundation; Telecom (Telstra Corporation Limited, Melbourne); Weight Watchers Australia Inc. supported the employment of Anne (Harley) Barton and Nicole (Grojan) McGrath as Research Assistants to undertake the monthly clinical measurements and Andrew Saul, Medical X-ray Technologist, who administered the DXA scans. In addition the grants covered the costs of the biochemical analyses undertaken in the Biochemistry and Endocrinology departments of the Royal Melbourne Hospital and the Department of Chemical Pathology at St Vincent's Hospital, Melbourne. The overall management of the study and counselling of subjects for the interventions was undertaken by Janet Pritchard, a full-time member of the University of Melbourne academic staff. We thank Telecom (Melbourne) and the Telstra employees, who were the subjects of the study, for their agreeable participation.

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Department of Medicine, University of Melbourne, Parkville, Victoria 

J.E. Pritchard, PhD, MSc, APD Research Dietitian, Royal Melbourne Hospital, Honorary Fellow, Department of Physiology

J.D. Wark, MBBS, PhD, FRACP, Professor, Head of Bone and Mineral Service, Royal Melbourne Hospital

School of Health Sciences, Deakin University, Burwood, Victoria 

C.A. Nowson, PhD, APD, Senior Lecturer, Research Dietitian

T. Billiongton, Adjunct Professor, formerly Senior Research Scientist, Lipid Reference Laboratory, Department of Chemical Pathology, St Vincent's Hospital, Melbourne

Correspondence: J. Pritchard, Department of Physiology, University of Melbourne, Parkville, Vic 3010. Email: [e-mail]