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Träfflista för sökning "WFRF:(Löf Marie) srt2:(2002-2004)"

Sökning: WFRF:(Löf Marie) > (2002-2004)

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1.
  • Löf, Marie, 1971-, et al. (författare)
  • Assessing physical activity of women of childbearing age. Ongoing work to develop and evaluate simple methods
  • 2002
  • Ingår i: Food and Nutrition Bulletin. - 0379-5721 .- 1564-8265. ; 23:3 SUPP, s. 30-33
  • Tidskriftsartikel (refereegranskat)abstract
    • Simple methods were developed and evaluated to assess total energy expenditure in 24 healthy, Swedish women planning pregnancy. Total energy expenditure was measured by the doubly-labeled water method (reference method) and three simple methods: heart rate recording, movement registration by an accelerometer, and a questionnaire. Mean total energy expenditure obtained by the four methods varied between 2,530 kcal per 24 hours (10,570 kJ/24 hours) and 2,730 kcal per 24 hours (11,420 kJ/24 hours). No significant difference between the results obtained by the different methods was found. The mean difference between the simple method and the reference method was for the questionnaire 204 +/- 508 kcal per 24 hours (853 +/- 2,124 kJ/24 hours), for the heart rate recorder 58 +/- 338 kcal per 24 hours (241 +/- 1,416 kJ/24 hours) and for the accelerometer 6 +/- 325 kcal per 24 hours (25 +/- 1,360 kJ/24 hours). The heart rate recorder and the questionnaire overestimated high and underestimated low energy expenditures. The accelerometer and the heart rate recorder were able to assess mean total energy expenditure of groups. No systematic bias was found when the accelerometer was used.
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2.
  • Löf, Marie, 1971-, et al. (författare)
  • Comparison of commonly used procedures, including the doubly-labelled water technique, in the estimation of total energy expenditure of women with special reference to the significance of body fatness
  • 2003
  • Ingår i: British Journal of Nutrition. - 0007-1145 .- 1475-2662. ; 90:5, s. 961-968
  • Tidskriftsartikel (refereegranskat)abstract
    • According to the report of the World Health Organization (1985), total energy expenditure (TEE) in human subjects can be calculated as BMR × physical activity level (PAL). However, other reports have pointed out limitations in the suggested procedure related to the % body fat of the subjects. The purpose of the present study was to evaluate the World Health Organization (1985) procedure in thirty-four healthy women with BMI 18-39 kg/m2. BMR and TEE were measured using indirect calorimetry (BMRmeas) and the doubly-labelled water method (TEEref) respectively. When assessed using the doubly-labelled water and skinfold-thickness methods, the women had 34 (SD 8) and 33 (SD 6) % body fat respectively. On the basis of guidelines provided by the World Health Organization (1985), 1.64 was selected to represent the average PAL of the women. Furthermore, PAL was also assessed by means of an accelerometer (PALacc), heart-rate recordings (PALHR) and a questionnaire (PALq). These estimates were: PALacc 1.71 (SD 0.17), PALHR 1.76 (SD 0.24), PALq 1.86 (SD 0.27). These values were lower than TEEref/BMRref, which was 1.98 (SD 0.21). BMR assessed using equations recommended by the World Health Organization (1985) (BMRpredicted) overestimated BMR by 594 (SD 431) kj/24 h. However, when TEE was calculated as BMRpredicted × PALacc, BMRpredicted × PALHR and BMRpredicted × PALq respectively, average results were in agreement with TEEref. Furthermore, TEE values based on BMRpredicted and PALacc, PALHR, PALq as well as on PAL = 1.64, minus TEEref, were significantly correlated with body fatness. When the same PAL value (1.64) was used for all subjects, this correlation was particularly strong. Thus, the World Health Organization (1985) procedure may give TEE results that are biased with respect to the body fatness of subjects.
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3.
  • Löf, Marie, 1971-, et al. (författare)
  • Evaluation of bioimpedance spectroscopy for measurements of body water distribution in healthy women before, during, and after pregnancy
  • 2004
  • Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 96:3, s. 967-973
  • Tidskriftsartikel (refereegranskat)abstract
    • Bioimpedance spectroscopy (BIS) is a technique of interest in the study of human pregnancy because it can assess extracellular (ECW), intracellular (ICW), and total body water (TBW) as ECW plus ICW. The technique requires appropriate resistivity coefficients and has not been sufficiently evaluated during the reproductive cycle. Therefore, in a methodological study, we estimated ECW, ICW, and TBW, by means of BIS, and compared the results with the corresponding estimates obtained by using reference methods. Furthermore, results obtained by means of population-specific resistivity coefficients were compared with results obtained by means of general resistivity coefficients. These comparisons were made before pregnancy, in gestational weeks 14 and 32, as well as 2 wk postpartum in 21 healthy women. The reference methods were isotope and bromide dilution. Average ICW, ECW, and TBW, estimated by means of BIS, were in agreement with reference data before pregnancy, in gestational week 14, and postpartum. The corresponding comparison in gestational week 32 showed good agreement for ICW, whereas estimates by means of BIS were significantly (P < 0.001) lower than the corresponding reference values for ECW and TBW. Thus the BIS technique, which was based on a model developed for the nonpregnant body, estimated increases in ICW accurately, whereas increases in ECW and TBW tended to be underestimated. Estimates obtained by using population-specific and general resistivity coefficients were very similar. In conclusion, the results indicated that BIS is potentially useful for studies during pregnancy but that further work is needed before it can be generally applied in such studies.
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4.
  • Löf, Marie, 1971-, et al. (författare)
  • Hydration of fat-free mass in healthy women with special reference to the effect of pregnancy
  • 2004
  • Ingår i: American Journal of Clinical Nutrition. - 0002-9165 .- 1938-3207. ; 80:4, s. 960-965
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Knowledge of the biological variability of the hydration factor (HF), ie, the ratio between total body water and fat-free mass, is important when calculating total body fat by means of the commonly used two-component model, which is based on estimates of body weight and total body water. The effect of pregnancy on the biological variability of HF, and consequently on the precision of the two-component model, is unknown.Objective: Our goal was to assess the effect of pregnancy on HF and its biological variability.Design: HF was assessed in 33 women planning pregnancy and in 17 of these women during gestational weeks 14 and 32 and 2 wk postpartum. HF was calculated by using estimates of body weight, total body water obtained by means of deuterium dilution, and body volume measured by using underwater weighing.Results: In the 17 women who became pregnant, HF was 0.718 ± 0.023, 0.723 ± 0.031, 0.747 ± 0.017, and 0.734 ± 0.020 before pregnancy, in gestational week 14, in gestational week 32, and 2 wk postpartum, respectively. The biological variability represented ≈2% of average HF in the nonpregnant state. The corresponding figure was >3% in gestational week 14 but ≤1.7% in gestational week 32.Conclusion: The two-component model for assessing body fat is as appropriate during late gestation as it is in the nonpregnant state, although its precision may be impaired when applied during the first part of pregnancy.
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5.
  • Löf, Marie, 1971- (författare)
  • Studies on energy metabolism and body composition of healthy women before, during and after pregnancy
  • 2004
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Current recommendations propose that an entire pregnancy requires an additional amount of energy from the diet equivalent to 335 000 kJ. This figure is mainly based on increases in the basal metabolic rate (BMR) and retention of total body fat (TBF). The BMR response to pregnancy varies considerably among women, but the factors responsible for this variability are unknown. TBF can be calculated from total body water (TBW) and the hydration factor (HF), using the so-called two-component model. However, the validity of this model during pregnancy has been questioned. Furthermore, current recommendations propose that energy needs during pregnancy may be partly offset by reductions in physical activity, but this statement is supported by little experimental evidence. The aims of this thesis were: to evaluate if the physical activity level (PAL) can be estimated by means of heart rate recording, accelerometry, and a questionnaire in women planning pregnancy; to assess the effect of pregnancy on energy expenditure due to physical activity, on activity pattern and on the biological variability of HF; to evaluate the use of bioimpedance spectroscopy (BIS) for assessing TBW during pregnancy; and to identifY factors explaining the variability of the BMR response to pregnancy.Healthy women were studied before pregnancy (n=38), and in gestational weeks 8, 14, 20, 32, 35 and 2 weeks post partum (n=23). Total energy expenditure (TEE), BMR, TEE/BMR, activity pattern, body composition, circulatory variables and serum levels of thyroid hormones and insulin growth factor-I (IGF-1) were measured. Foetal weight in gestational week 31 and infant birth weight were assessed.All estimates of PAL were imprecise and too low in women planning pregnancy. There was little change in TEE/BMR in gestational week 14, but it was significantly reduced in gestational week 32. However, activity pattern was largely unaffected by pregnancy. The biological variability of HF was 2%, 3% and 1.7% or less of average HF before pregnancy and in gestational weeks 14 and 32, respectively. BIS underestimated TBW during pregnancy. In gestational week 14, the increase in BMR correlated significantly with the increase in body weight and with TBF (%)before pregnancy. Together these variables explained about 40% of the variability in the BMR response. In gestational week 32, the increase in BMR correlated significantly with changes in body weight, TBF, fat-free mass, IGF-I, cardiac output and free triiodothyronine. At this stage of gestation the increase in body weight in combination with foetal weight or with the increased levels of IGF-I in serum explained about 60% of the variability of the increased BMR.In conclusion: I) Heart rate recording, accelerometry and the questionnaire produced inappropriate PAL estimates. 2) In women maintaining their pre-pregnant activity pattern the increase in BMR represents the major component of the increased energy expenditure during pregnancy. 3) The two-component model for assessing TBF is appropriate in late gestation, while its precision may be impaired in early pregnancy. 4) BIS in its present form is not appropriate for assessing TBW during pregnancy. 5) Nutritional factors are important regarding the variability in the BMR response to pregnancy.
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7.
  • Löf, Marie, 1971-, et al. (författare)
  • Validation of energy intake by dietary recall against different methods to assess energy expenditure
  • 2004
  • Ingår i: Journal of human nutrition and dietetics (Print). - 0952-3871 .- 1365-277X. ; 17:5, s. 471-480
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives. To compare the validity of dietary recalls and physical activity recalls and investigate some factors influencing this validity. To provide an example showing how procedures based on recalls of physical activity can assess the validity of dietary recalls and identify subjects constantly underreporting their energy intake (EI). Design and subjects. Thirty-seven women were studied using three 24-h dietary recalls, two kinds of physical activity recalls, indirect calorimetry and the doubly labelled water method. Results. The EI obtained using dietary recalls were biased with respect to body mass index (BMI) and attitudes towards body weight and dieting, whereas results obtained using a physical activity recall were not. Eighteen women produced underreports (UR), i.e. their average EI was below 76% of total energy expenditure (TEE), whereas 24 women reported an EI that was lower than TEE on all three recall days, i.e. constantly underreporting subjects. A physical activity recall identified 13 URs and 20 of the constantly underreporting subjects. Conclusions. In contrast to estimates of EI, TEE assessed using physical activity recalls was not biased with respect to BMI or attitudes towards body weight and dieting. Recalls of physical activity represent potentially useful procedures for identifying URs and constantly underreporting subjects but are not accurate enough for individuals.
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