Breast cancer risk among first-generation migrants in the Netherlands.

We investigated breast cancer incidence in migrants in the Netherlands in 1988-1998. The standardised incidence ratio for breast cancer in Northwest-Netherlands was statistically significantly reduced for women born in Surinam (0.56), Turkey (0.29) and Morocco (0.22). The proportion of women with advanced stages (III and IV) did not differ significantly between migrants and women born in the Netherlands.

Physical activity and breast cancer risk in women aged 20-54 years.

BACKGROUND/METHODS: Although several studies have suggested that physical activity is associated with a decreased risk of breast cancer, such a decrease has not been found consistently, perhaps because physical activity was assessed in different ways and for restricted periods. Few studies have assessed the risk of breast cancer in relation to lifetime physical activity. We used data from a population-based, case-control study, including 918 case subjects (aged 20-54 years) and 918 age-matched population control subjects, to examine associations between breast cancer risk and physical activity at ages 10-12 years and 13-15 years, lifetime recreational activity, and title of longest held job. RESULTS: Women who were more active than their peers at ages 10-12 years had a lower risk of breast cancer (odds ratio [OR] = 0.68; 95% confidence interval [CI] = 0.49-0.94). Women who had ever engaged in recreational physical activity had a reduced risk of breast cancer compared with inactive women (OR = 0.70; 95% CI = 0.56-0.88). Neither very early recreational activity (before age 20 years) nor recent activity (last 5 years) was associated with a greater reduction in risk than recreational activity in the intermediate period. Furthermore, women who started recreational activities after age 20 years and women who started earlier and continued their activities throughout adult life experienced a similar reduction in risk. Lean women, i.e., women with a body mass index (weight in kg/[height in m](2)) less than 21. 8 kg/m(2), appeared to have a lower risk associated with recreational physical activity than women with a body mass index greater than 24.5 kg/m(2) (OR = 0.57 [95% CI = 0.40-0.82] and OR = 0. 92 [95% CI = 0.65-1.29], respectively). CONCLUSIONS: Our findings support the hypothesis that recreational physical activity is associated with a decreased risk of breast cancer. Physical activity in early or recent life does not appear to be associated with additional beneficial effects.

p53 protein overexpression in relation to risk factors for breast cancer.

To investigate whether breast tumors developing through a pathway with p53 protein overexpression (p53+) show different risk factor associations compared with breast tumors without p53 overexpression (p53-), the authors determined p53 overexpression in tissue sections of 528 patients with invasive breast cancer by using immunohistochemistry. These patients and 918 healthy controls aged 20-54 years participated in a Netherlands population-based case-control study on oral contraceptives in 1986-1989. A total of 142 tumors (27%) demonstrated clear p53 overexpression (p53+). Most risk factors did not show different associations with p53+ and p53- tumors. However use of oral contraceptives for 9 or more years was associated with a 2.5-fold increase in the risk of p53+ tumors (95% confidence interval 1.4-4.4; test for trend with months of use, p = 0.01), whereas such use increase the risk of p53- tumors only 1.4-fold (95% confidence interval 0.9-2.1; test for trend p = 0.06). Prolonged lactation > or = 25 weeks) was associated with a 40% reduction in risk of p53+ tumors (odds ratio = 0.6; 95%, confidence interval 0.3-1.0; test for trend with weeks of lactation, p = 0.09), whereas the risk of p53- tumors was not associated with lactation. The authors conclude that p53+ and p53- breast tumors are not associated with very distinct risk profiles but that the stronger associations of p53+ tumors with oral contraceptive use and lactation suggest differences in risks that deserve further investigation. If these findings can be confirmed and possible molecular mechanisms explored, this may help to elucidate the associations between these risk factors and breast cancer in general.

Visceral fat accumulation in relation to sex hormones in obese men and women undergoing weight loss therapy.

In 70 healthy obese subjects (37 men and 33 premenopausal women; aged 27-51 yr; body mass index, 28-38 kg/m2), associations between the initial amount of visceral fat and sex hormone levels were studied as well as between changes that occurred in response to a 4.2 mJ/day deficit diet for 13 weeks. Magnetic resonance imaging was used to quantify the visceral fat depot. In women, an abundance of visceral fat was significantly associated with diminished levels of sex hormone-binding globulin and free 17 beta-estradiol/free testosterone (T) ratio and to elevated levels of free T after adjustment for age and total fat mass. In men, no significant relationships could be found between visceral fat accumulation and any of the sex hormones. Mean total fat loss was 11.3 +/- 3.3 (+/- SD) kg. In women, loss of visceral fat was significantly related to rises in the sex hormone-binding globulin level and the free 17 beta-estradiol/free T ratio independent of total fat loss, whereas in men, only the association between visceral fat loss and increased estrone level reached statistical significance. In conclusion, in obese premenopausal women, visceral fat predominance seems to be related to a relatively increased androgenicity. In obese men, sex steroid levels appear not to depend on the amount of visceral fat. In obese women, but not in obese men, visceral fat loss seems to be accompanied by a relative reduction in androgenicity.

Effect of a weight cycle on visceral fat accumulation.

Magnetic resonance imaging was used to study the effect of a single weight cycle on three fat depots: the visceral and subcutaneous abdominal depots and the subcutaneous depot at the trochanter level. Obese subjects (17 men, 15 women) were examined before and after weight-loss intervention and 67 wk after intervention. They lost 12.9 +/- 3.3 (mean +/- SD) kg body wt during intervention and regained 11.9 +/- 5.1 kg during follow-up. Weight regain did not result in greater body fatness than before weight loss (initial fat mass: 34.3 +/- 6.1 kg, final fat mass: 32.8 +/- 7.7 kg; P = 0.047). There was no indication of a preferential deposition of visceral fat after weight regain (initial visceral fat area: 120 +/- 41 cm2, final visceral fat area: 110 +/- 48 cm2; P = 0.087). On the contrary, there was a slight tendency to accumulate subcutaneous fat at the expense of visceral fat. It is concluded that weight loss followed by weight regain neither leads to a greater body fatness nor to a larger amount of visceral fat compared with before weight loss.

Relative effects of weight loss and dietary fat modification on serum lipid levels in the dietary treatment of obesity.

The independent effects of weight loss and dietary fat modification on serum lipids were investigated in two groups of healthy moderately obese men and women. In one group (sequential group, n = 19), a weight-stable low-fat, low-saturated-fat diet (Low-Sat) was given for 7 weeks (= dietary modification), followed by a 4.2 MJ/day deficit Low-Sat diet for 13 weeks (i.e., weight loss alone). Another group (simultaneous group, n = 22) received a 4.2 MJ/day deficit Low-Sat diet for 13 weeks (i.e., weight loss+dietary fat modification). Each group was subject to an initial weight-stable high-fat, high-saturated fat diet for 3 weeks and a final weight stable Low-Sat diet for 3 weeks. Both groups lost similar amounts of body weight, about 13 kg, and had similar overall changes in total cholesterol, low density lipoprotein (LDL), cholesterol, high density lipoprotein (HDL) cholesterol, the HDL/LDL ratio, and triglycerides. Analysis of the separate effects of the Low-Sat diet without energy restriction and of weight loss in the sequential group showed that weight loss per se was responsible for about 50% of the total reduction in total cholesterol, and for about 60% and 70% of the fall in LDL cholesterol and triglycerides, respectively. Fat modification without weight loss reduced HDL cholesterol by 11.1% and the HDL/LDL ratio by 7.7%, while weight loss per se led to increases in HDL cholesterol of 12.5% and in the HDL/LDL ratio of 24.0%. We conclude that the effects of reduction in fat and saturated fat intake and weight loss are additive.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian rhythms of appetite at different stages of a weight loss programme.

A group of 28 healthy obese people (16 women, 12 men) rated their appetite each whole hour of the day during nine separate days at three different stages of a dietary intervention study of 24 weeks. The first stage was an introduction period of eight weeks in which subjects were weight stable. The second stage was a weight reduction period of 13 weeks in which subjects lost about 0.85 kg/week of body weight. In the third stage of three weeks subjects were weight stable again. The slimming diet, which contained predominantly sweet items, had an energy content which was 1000 kcal (4.2 MJ) below the individually estimated daily energy expenditure. The results showed that appetite for a meal increased in the first week of the weight reduction period of 13 weeks but returned to the baseline level within 4-8 weeks. Appetite for something savoury remained elevated during the entire weight reduction period, and returned to the baseline level in the stabilization period. Appetite for something sweet did not change. The circadian rhythms of the different types of appetite remained unchanged at all stages during the diet intervention programme. Different types of appetite (e.g. sweet, savoury) had different patterns over the day.

Abdominal diameters as indicators of visceral fat: comparison between magnetic resonance imaging and anthropometry.

The aim of the present study was to investigate the usefulness of abdominal diameters to indicate visceral fat, their relationship with serum lipids and their capability of detecting changes in visceral fat. Before and after weight loss, visceral and subcutaneous fat, and the sagittal and transverse diameters were assessed by magnetic resonance imaging (MRI) in forty-seven obese men and forty-seven premenopausal obese women with an initial body mass index of 31.0 (SD 2.4) kg/m2. In a subsample (n 21), diameters, were also measured by anthropometry in the standing and supine positions. They were strongly correlated with the diameters derived from the MRI scans. Serum levels of total and HDL-cholesterol and triacylglycerol were measured before weight loss. In women the sagittal diameter correlated less strongly with visceral fat than anthropometrically-assessed waist circumference and waist:hip ratio (WHR). In men these associations were comparable. Changes in visceral fat with weight loss were more strongly correlated with changes in the sagittal diameter and sagittal:transverse diameter ratio (STR) than with changes in waist circumference or WHR in men. In women, changes in the anthropometric variables and the separate diameters (except STR) were not associated with visceral fat loss. In men, but not in women, both the sagittal diameter and the visceral fat area were related to serum lipids. It is concluded that the sagittal diameter and STR may have advantages over waist circumference and WHR in men, particularly in assessing changes in visceral fat, but this could not be demonstrated in women. The ability to predict visceral fat from circumferences and diameters or their ratios is, however, limited in obese men and women.

Techniques for the measurement of visceral fat: a practical guide.

The measurement of fat distribution has become an important issue in obesity research. Numerous techniques have been developed to assess visceral fat because this fat seems to be most strongly associated with metabolic disorders. This review focuses on methods for the direct and indirect assessment of visceral fat ranging from multiple-scan computerized tomography to anthropometric measurements. The principles of techniques, their accuracy and reproducibility as well as aspects of costs and safety are discussed. Comparison of the different methods shows that imaging techniques, such as computerized tomography and magnetic resonance imaging, are the optimal techniques available for accurate assessment of visceral fat. Methods other than imaging techniques have limited potential in the measurement of changes in visceral fat deposition. Anthropometric measurements can be useful to classify subjects into different types of fat distribution for diagnosis of abdominal obesity, and for general application in epidemiological studies. The choice of a particular technique should be based on a balance of practical and financial considerations and the aim of the study. Involvement of ionizing radiation exposure may be an important element in the decision-making process.

Visceral fat loss measured by magnetic resonance imaging in relation to changes in serum lipid levels of obese men and women.

The effect of weight reduction on serum lipids in relation to visceral fat accumulation was studied in 78 healthy obese subjects (40 premenopausal women and 38 men) aged 27-51 years and with an initial body mass index of 30.7 +/- 2.2 kg/m2 (mean +/- SD). The subjects received a 4.2 MJ/day energy-deficit diet for 13 weeks. Magnetic resonance imaging was used to assess abdominal fat areas before and after weight loss. Weight reductions of 12.6 +/- 3.2 kg in men and 11.7 +/- 3.8 kg in women resulted in larger reductions in the fasting serum levels of total cholesterol (p < 0.05), low density lipoprotein cholesterol (p = 0.06), and triglycerides (p < 0.01) and a larger increase in the high density lipoprotein cholesterol/low density lipoprotein cholesterol ratio (p = 0.05) in men compared with women. Men also lost more visceral fat (p < 0.0001), whereas the reductions in the total and subcutaneous abdominal fat depots were similar. In women, visceral fat loss was significantly related with an increase of the high density lipoprotein cholesterol level, independent of the degree of total fat loss. In men, however, no significant correlations were observed between changes in visceral fat and any of the serum lipids. Comparisons of average changes in obese men and women suggest that visceral fat loss is associated with an improvement of the serum lipid profile. However, correlation analysis does not support a critical role of visceral fat in determining serum lipid concentrations on an individual level, except for an improvement of the high density lipoprotein cholesterol level with visceral fat loss in obese women.

Waist-hip ratio is a poor predictor of changes in visceral fat.

Magnetic resonance imaging was used to study the effect of weight loss on three fat depots: the visceral and subcutaneous abdominal depots and the subcutaneous depot at trochanter level. Changes in fat depots were compared with changes in circumference measures and the waist-hip ratio (WHR) in obese men (n = 38) and women (n = 40). Mean weight loss was (mean +/- SD) 12.9 +/- 3.5 kg (P < 0.001). The proportional reduction of fat was largest in the visceral depot (men 40%, women 33%). Less fat was lost subcutaneously, especially at trochanter level (men 29%, women 26%). WHR decreased significantly in both sexes (P < 0.001). Change in WHR was not significantly related to the absolute reduction in visceral fat. Total body-fat loss showed a stronger association with subcutaneous fat loss than with visceral fat loss. The findings suggest that fat distribution may change with weight loss, particularly by the loss of visceral fat, but changes in WHR are not appropriate for evaluating changes in this fat depot.

Visceral fat accumulation in obese subjects: relation to energy expenditure and response to weight loss.

Seventy-eight healthy obese subjects, 40 premenopausal women and 38 men aged 27-51 yr received a 4.2 MJ/day energy-deficit diet for 13 wk. Resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) were measured by indirect calorimetry. Abdominal subcutaneous and visceral fat areas were calculated from magnetic resonance imaging scans before and after weight loss. Before weight loss, visceral fat accumulation was positively correlated with higher levels of RMR (P < 0.05) and DIT (P < 0.01) in women but not in men. The mean weight reduction was 12.2 +/- 3.5 (SD) kg. In men but not in women, an initially large visceral fat depot was associated with a reduced loss of weight and total fat mass (P < 0.05). Within each sex, an initial abundance of visceral fat was significantly related to a larger loss of visceral fat (P < 0.001) and in men to a smaller loss of subcutaneous fat (P < 0.05). These results suggest that there may be gender differences in the associations between visceral fat accumulation and components of energy expenditure (RMR and DIT) in obese subjects. Obese subjects with an initial abundance of visceral fat do not lose more body weight but more visceral fat than subjects with less visceral fat.

Changes in fat-free mass in obese subjects after weight loss: a comparison of body composition measures.

Estimates of body composition by densitometry were made in 84 apparently healthy subjects (42 men, 42 women) with a mean age of 40 +/- 6 years (mean +/- s.d.), before and after weight loss. The initial body mass index (BMI) was 30.7 +/- 2.3 kg/m2 and the achieved weight loss on a 4.2 MJ/day energy deficit diet for 13 weeks was 12.2 +/- 3.7 kg. The results by densitometry were compared with estimates obtained by four other techniques: deuterium oxide dilution, skinfold thickness, bioelectrical impedance (three equations) and BMI (two equations). The fat-free mass (FFM) loss estimated by densitometry in men and women was 2.8 +/- 1.8 kg and 1.3 +/- 1.3 kg respectively. The dilution technique gave comparable results with densitometry. The losses of FFM assessed by skinfold thicknesses, BMI and impedance equations were almost similar, but significantly larger than the reduction in FFM measured by densitometry. These deviations were mainly the result of significantly larger differences from densitometry before compared to after weight loss. No correlation was found between change in FFM by densitometry and change in resistance measured by the bioelectrical impedance method in both sexes. It is concluded that application of published prediction formulae in weight loss studies are less appropriate and will lead to changes in FFM that are significantly different from the changes estimated by densitometry or deuterium oxide dilution.

Visceral fat accumulation measured by magnetic resonance imaging in relation to serum lipids in obese men and women.

In 91 apparently healthy obese subjects (45 premenopausal women and 46 men) the associations between specific fat depots and serum lipids were studied. Magnetic resonance imaging was used to quantify fat depots at abdominal and hip level. In women, an accumulation of visceral fat was associated with a less favourable lipid profile, even after adjustment for age and body fat percentage: higher triglycerides levels (P less than 0.001), lower levels of HDL-cholesterol (P less than 0.01) and a diminished HDL-cholesterol/LDL-cholesterol ratio (P less than 0.01). In men, however, the significant inverse relationship between an abundance of visceral fat and the HDL-cholesterol/LDL-cholesterol ratio and the significant positive correlations with total-, LDL-cholesterol and triglycerides disappeared after adjustment for age and fat percentage. Within each sex, subcutaneous fat neither at abdominal level nor at hip level was significantly related to serum lipids. It is concluded that there are gender differences in the associations between visceral fat accumulation and serum lipids.

Sex and age specific prediction formulas for estimating body composition from bioelectrical impedance: a cross-validation study.

In 827 male and female subjects, with a large variation in body composition and an age range of 7-83 years, body composition was measured by densitometry, anthropometry and bioelectrical impedance. The relationship between densitometrically determined fat free mass (FFM) with body impedance (R), body weight (W) and body height (H) was analysed, taking age and sex into account. The intercept of the regression equation FFM = a x H2/R + b was found to be age, and (at older ages) sex dependent, increasing from age 7 to age 15, and slowly decreasing after age 16. Therefore the population was subdivided into two age categories, the one 15 years and younger, and the other 16 years and older. Each age category was randomly divided into two groups, A and B. In each age category the developed prediction formula for group A was cross-validated in group B, and vice versa. No statistically and biologically meaningful differences between predicted and measured FFM were observed in either group. Therefore the data of group A and B in each age category were combined. The best fitted prediction formula at ages less than or equal to 15 was: FFM = 0.406 x 10(4) x H2/R + 0.360 W + 5.58 H + 0.56 Sex - 6.48: n = 166, R2 = 0.97, SEE = 1.68 kg (cv% = 4.9 percent); and at ages greater than or equal to 16: FFM = 0.340 x 10(4) x H2/R + 15.34 H + 0.273 W - 0.127 age + 4.56 sex - 12.44: n = 661, R2 = 0.93, SEE = 2.63 kg (cv% = 5.0 percent).(ABSTRACT TRUNCATED AT 250 WORDS)

Imaging techniques for measuring adipose-tissue distribution--a comparison between computed tomography and 1.5-T magnetic resonance.

We developed a method for calculating adipose-tissue areas from transverse body scans by magnetic-resonance imaging (MRI). The method is based on an inversion recovery experiment (repetition time 820 ms, inversion delay time 300 ms, and echo time 20 ms). Total-fat areas and subcutaneous-fat areas were calculated by this method and by computed tomography (CT) from abdominal scans taken in seven male volunteers. The SEE ranged from 4.4 cm2 (CV 4.4%) for subcutaneous-fat areas to 8.3 cm2 (CV 12.8%) for visceral-fat areas. The reproducibility of measuring fat areas with MRI was assessed in seven other volunteers (four males, three females). The average errors of the method for different fat areas were 5.4%, 10.6%, and 10.1% for total-, visceral-, and subcutaneous-fat areas, respectively. We conclude that CT and MRI may yield different absolute values of fat areas (especially visceral fat) but that the ranking of individuals on the basis of their fat areas will be similar by both methods.

The effect of psychological stress on diet-induced thermogenesis and resting metabolic rate.

The effect of psychological stress on resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) was assessed in 12 healthy young non-obese men of body weight 70.2 +/- 1.2 kg (mean +/- s.e.m.) and age 25 +/- 0.6 years. Two types of commercially available motion pictures (video films) were shown to the subjects during the measurements, ie stress-inducing horror films and as a control, romantic family films. The study was conducted according to a cross-over design. RMR and respiratory quotients were not significantly influenced by the type of film shown to the subjects. DIT, assessed over 4 h, was significantly increased by the stress-inducing treatment, 0.95 +/- 0.05 kJ/min (mean +/- s.e.m.) versus 0.76 +/- 0.06 kJ/min (control). No significant effect was observed of psychological stress on postprandial substrate oxidation rates, nutrient balances, and urinary catecholamine excretion.

Body impedance is largely dependent on the intra- and extra-cellular water distribution.

Electrical impedance measurements were performed in fasting blood samples and analysed in relation to packed cell volume and calculated intra- and extra-cellular water distribution. The total blood impedance was shown to be strongly dependent on the ratio of intra-cellular water to total water (r = 0.97, P less than 0.0001). In a group of 515 subjects, with a large variation in age and body composition, the relation between the body impedence corrected for fat-free mass and body height (the specific body impedance) and the calculated ratio of intra-cellular water to total body water, was found to be similar to that in blood. From these observations a regression model was developed and applied to body compositional data of several groups of subjects before and after weight loss caused by water losses. It was possible to calculate at a group level the losses of intra- and extra-cellular water, which confirms the applicability of the model. It is concluded that the validity of the predicted fat-free mass or total body water from body impedance is largely dependent on the water distribution in the measured subjects. This means that age- and sex-specific prediction formulas have to be used for the assessment of the body composition and that the bio-electrical impedance method is only with caution applicable in subjects with a disturbed water distribution as in oedema, pregnancy and dehydration.