Jennifer C. Lovejoy

Increased visceral fat and decreased energy expenditure during the menopausal transition

Objective:This study assessed longitudinal changes in body composition, fat distribution and energy balance in perimenopausal women. We hypothesized that total fat and abdominal body fat would increase at menopause due to decreased energy expenditure (EE) and declining estrogen, respectively.Design:Observational, longitudinal study with annual measurements for 4 years.Subjects:Healthy women (103 Caucasian; 53 African-American), initially premenopausal. During follow-up, lack of menstruation for 1 year and follicle-stimulating hormone >30u2009mIUu2009ml−1 defined a subject as postmenopausal.Measurements:Fat and lean mass (dual-energy X-ray absorptiometry), visceral (VAT) and subcutaneous abdominal fat (SAT) (computed tomography), dietary intake (4-day food record), serum sex hormones and physical activity (tri-axial accelerometry). Twenty-four hour EE was measured by whole-room calorimeter in a subset of 34 women at baseline and at year 4.Results:Body fat and weight increased significantly over time only in those women who became postmenopausal by year 4 (n=51). All women gained SAT over time; however, only those who became postmenopausal had a significant increase in VAT. The postmenopausal group also exhibited a significant decrease in serum estradiol. Physical activity decreased significantly 2 years before menopause and remained low. Dietary energy, protein, carbohydrate and fiber intake were significantly higher 3–4 years before the onset of menopause compared with menopause onset. Twenty-four hour EE and sleeping EE decreased significantly with age; however, the decrease in sleeping EE was 1.5-fold greater in women who became postmenopausal compared with premenopausal controls (−7.9 vs −5.3%). Fat oxidation decreased by 32% in women who became postmenopausal (P<0.05), but did not change in those who remained premenopausal.Conclusion:Middle-aged women gained SAT with age, whereas menopause per se was associated with an increase in total body fat and VAT. Menopause onset is associated with decreased EE and fat oxidation that can predispose to obesity if lifestyle changes are not made.

Abdominal fat distribution and metabolic risk factors: Effects of race☆

Previous studies have shown differences between African-American and Caucasian populations in the prevalence of obesity and obesity-related diseases such as type IIoffabetes. The purpose of this study was (1) to compare the insulin sensitivity index (SI) from the minimal model in 37 African-American and 22 Caucasian women matched for age and obesity, and (2) to determine whether the relationship between intraabdominal fat distribution and SI (and other health risk factors) was similar in both races. To address the second question, intraabdominal fat distribution was assessed by computed tomographic (CT) scans in a subset of 23 African-American and 15 Caucasian women. Despite having a similar body mass index ([BMI] weight in kilograms divided by height in meters squared) and waist to hip ratio (WHR), African-American women had a mean SI value that was approximately 36% lower than in the Caucasian women (3.45 +/- 0.42 v 5.40 +/- 0.55 x 10(-5) min(-1) / pmol x L, P = .007). Visceral fat area was smaller in African-American women (98.0 +/- 8.5 CM2) than in Caucasian women (117.3 +/- 12.4 CM2) despite similar BMI and WHR. Visceral fat area was strongly correlated with WHR in the Caucasian women (r = .76, P < .001), as previously observed, but not in the African-American women (r = .24, NS). WHR was significantly correlated with fasting insulin and serum cholesterol in the Caucasian women but not in the African-Americans. Visceral fat was correlated with metabolic risk factors in both groups, but subcutaneous abdominal fat was significantly correlated with SI and fasting insulin only in the African-American women. These results suggest that the relationship between body fat distribution and health risk factors may be different in African-Americans and Caucasians. Additionally, reduced insulin sensitivity in African-American women may in part explain the high diabetes rate in this population.

The relation of gender, race and socioeconomic status to obesity and obesity comorbidities in a sample of US adults

OBJECTIVE: To examine the obesity-related chronic diseases in the US adult population according to gender, race and socioeconomic status.METHODS: Data from the 1994–1996 Continuing Survey of Food Intakes by Individuals (1994–1996 CSFII) conducted by the US Department of Agriculture/Agricultural Research Service (USDA/ARS) were used in the analysis. Relevant data included self-reported weight and height, self-reported physician-diagnosed diabetes mellitus, hypertension, heart disease and high serum cholesterol. Analysis was conducted according to gender, race, income level and education level.RESULTS: There was a graded increase in diabetes, hypertension and high serum cholesterol with increasing body weight in nearly all gender, racial and socioeconomic groups. Among the obese individuals, the prevalence of hypertension was higher in black subjects and the prevalence of diabetes, hypertension and heart disease was higher in individuals with lower education compared to their counterparts. The odds of having diabetes, hypertension, heart disease and high serum cholesterol increased with increasing body weight after adjusting for age, gender, race, income, education and smoking.CONCLUSION: Although cross-sectional in nature, our results suggest that the disease burden associated with obesity in the population may be substantial. This burden increases with increasing severity of obesity. Our findings support the current opinion that, although the nature of obesity-related health risks is similar in all populations, the specific level of risk associated with a given level of obesity may be different depending on gender, race and socioeconomic condition.

The menopause and obesity

In summary, menopause tends to be associated with an increased risk of obesity and a shift to an abdominal fat distribution with associated increase in health risks. Changes in body composition at menopause may be caused by the decrease in circulating estrogen, and, for fat distribution shifts, the relative increase in the androgen-estrogen ratio is likely to be important. Clinicians need to be aware of the likelihood of weight gain during the perimenopausal and postmenopausal years because behavioral strategies for weight loss can be effectively used in this population. Weight loss or prevention of weight gain is likely to have significant health benefits for older women.

Effect of a controlled high-fat versus low-fat diet on insulin sensitivity and leptin levels in African-American and Caucasian women

African-American women have been shown to be more insulin-resistant than age- and weight-matched Caucasian women, but the reasons for this difference are unclear. The purpose of the present study was to determine whether experimental manipulation of dietary fat intake has differential effects by race on insulin sensitivity (S(I)) in 20 African-American and 11 Caucasian women. Additionally, leptin levels before and after 3 weeks of an isocaloric high-fat ([HF] 50% fat, 35% carbohydrate, and 15% protein) or low-fat ([LF] 20% fat, 55% carbohydrate, and 15% protein) diet were compared. African-American and Caucasian women did not differ significantly in the body mass index (BMI) or percentage body fat at baseline. S(I) (adjusted for BMI) decreased on the HF diet and increased on the LF diet in both races combined relative to the baseline control (control, 2.42 +/- 0.22; HF, 2.29 +/- 0.22; LF, 2.75 +/- 0.21 x 10(-4) min(-1)/microU x mL; main effect of diet, P = .04). There was a 6% decrease in S(I) on the HF diet compared with the control in women of both races, while the LF diet increased S(I) by 6% in African-American and 20% in Caucasian women. Leptin levels increased by 14% on the HF versus control diet in African-Americans (35.2 +/- 3.0 v 30.8 +/- 3.0 ng/mL, P < .01), but did not change with diet in Caucasian women. Glucose and insulin administration had no effect on leptin levels. We conclude that a HF diet consumed over several weeks reduces S(I) in healthy women of both races; however, the magnitude of increase in S(I) on a LF diet is greater in Caucasian women. The HF diet significantly increased leptin levels in African-American women, although there were no other influences of diet, insulin, or race on serum leptin.

Effects of consuming mycoprotein, tofu or chicken upon subsequent eating behaviour, hunger and safety

This study tested if: (1) a preload of mycoprotein and tofu consumed before a lunch meal have a greater effect on satiety when compared to a chicken preload, (2) the mycoprotein and tofu preloads, compared to chicken, are not associated with compensation or eating more food at a subsequent dinner meal. These hypotheses were tested in a controlled laboratory study using universal eating monitors to measure food intake and visual analogue scales to monitor hunger and satiety. Forty-two overweight adult females consumed three meals in the laboratory on 3 test days. At lunch, isocaloric pasta preloads, containing mycoprotein, tofu, or chicken, varied across the days in a balanced order. The findings of the study supported the two hypotheses. Mycoprotein and tofu preloads, in comparison to the chicken preload, were associated with lower food intake shortly after consuming the preload at lunch. Food intake following consumption of mycoprotein and tofu did not differ, and participants did not compensate for lower food intake at lunch by consuming more food at dinner. The findings suggest that mycoprotein and tofu have satiating properties that persist for several hours after a meal. These findings have significant implications for the development of foods that are low in kilojoules, but are also filling.

Impact of adopting a vegan diet or an olestra supplementation on plasma organochlorine concentrations: results from two pilot studies.

The aim of these studies was to evaluate the potential of some nutritional approaches to prevent or reduce the body load of organochlorines (OC) in humans. Study 1 compared plasma OC concentrations between vegans and omnivores while study 2 verified if the dietary fat substitute olestra could prevent the increase in OC concentrations that is generally observed in response to a weight-reducing programme. In study 1, nine vegans and fifteen omnivores were recruited and the concentrations of twenty-six OC (beta-hexachlorocyclohexane (beta-HCH), p, p-dichlorodiphenyldichloroethane (p, p-DDE), p, p-dichlorodiphenyltrichloroethane (p, p-DDT), hexachlorobenzene, mirex, aldrin, alpha-chlordane, gamma-chlordane, oxychlordane, cis-nonachlor, trans-nonachlor, polychlorinated biphenyl (PCB) nos. 28, 52, 99, 101, 105, 118, 128, 138, 153, 156, 170, 180, 183 and 187, and aroclor 1260) were determined. In study 2, the concentrations of these twenty-six OC were measured before and after weight loss over 3 months in thirty-seven obese men assigned to one of the following treatments: standard group (33 % fat diet; n 13), fat-reduced group (25 % fat diet; n 14) or fat-substituted group (1/3 of dietary lipids substituted by olestra; n 10). In study 1, plasma concentrations of five OC compounds (aroclor 1260 and PCB 99, PCB 138, PCB 153 and PCB 180) were significantly lower in vegans compared with omnivores. In study 2, beta-HCH was the only OC which decreased in the fat-substituted group while increasing in the other two groups (P = 0.045). In conclusion, there was a trend toward lesser contamination in vegans than in omnivores, and olestra had a favourable influence on beta-HCH but did not prevent plasma hyperconcentration of the other OC during ongoing weight loss.

Effect on Body Weight of Replacing Dietary Fat with Olestra for Two or Ten Weeks in Healthy Men and Women

Objective: To examine in two separate studies the effects of replacing dietary fat with Olestra on body composition and weight change in healthy young men and women. Methods: Ten healthy, lean young men participated in Study One that was a 22-day single blind, within-subject design. After a control diet (40% fat) for eight days Study One subjects received an Olestra-substituted diet (31% metabolizable fat) for 14 days. Study Two was a randomized parallel-arm clinical trial with 15 healthy, lean and overweight young women. These subjects were randomly assigned to receive a control diet (40% fat), an Olestra-containing diet (31% metabolizable fat) or a reduced-fat diet (31% fat) for 10 weeks. All foods were provided to the subjects, and energy intakes were not restricted. The primary endpoint in both studies was change from baseline in body weight. In Study Two, body composition was measured by dual energy x-ray absorptiometry. In both studies, food intake and nutrient compensation were assessed. Results: In Study One fat substitution by Olestra resulted in a significant 1.7 kg weight loss from baseline. In Study Two, change in body weight and body fat from baseline were statistically significant in all groups, but the group with Olestra lost significantly more weight from baseline (−5.0 kg) than the other two groups. In Study One there was partial compensation for the decreased energy intake, while in Study Two, compensation was seen only for those on the reduced-fat diet. Conclusion: Replacement of ⅓ of dietary fat with Olestra in periods of up to 10 weeks results in weight loss in men and women.

Common apolipoprotein A-IV variants are associated with differences in body mass index levels and percentage body fat.

OBJECTIVE: To determine the relationship between two common apoA-IV variants (Thr347→Ser; Gln360→His), and body mass index (BMI) and percentage body fat.DESIGN: Cross-sectional study.SUBJECTS: Eight-hundred and forty-eight subjects screened for participation in ongoing clinical studies.MEASUREMENTS: ApoA-IV genotype, body mass index, waist-to-hip ratio and percentage body fat by bioelectric impedance.RESULTS: Participants had an average age of 41±12u2005y and an average BMI of 28.2±5.5u2005kg/m2. Individuals homozygous for the Ser347 allele had higher BMI (32.3±6.6 vs 28.6±5.3u2005kg/m2;u2005P<0.01) and percentage body fat (36.9±7.8 vs 31.0±9.6%;u2005P<0.05) compared with individuals homozygous for Thr347. In contrast, the presence of at least one copy of the His360 allele was associated with lower BMI (27.2±5.0 vs 28.4±5.6u2005kg/m2;u2005P<0.05) and percentage body fat (28.6±8.2 vs 30.7±9.1%;u2005P<0.05). The genotype effects persisted after normalization of the data for the potential confounding effects of gender, age and race. When grouped by BMI percentile, the frequency of the Ser347/Ser347 genotype increased while the frequency of the His360 allele decreased with increasing BMI.CONCLUSIONS: These data suggest a role for apoA-IV in fat storage or mobilization and that genetic variations in the apoA-IV gene may play a role in the development of obesity.

Low-dose T3 improves the bed rest model of simulated weightlessness in men and women

This study tested the hypothesis that low-dose 3,5,3-triiodothyronine (T3) administration during prolonged bed rest improves the ground-based model of spaceflight. Nine men (36.4 ± 1.3 yr) and five women (34.2 ± 2.1 yr) were studied. After a 5-day inpatient baseline period, subjects were placed at total bed rest with 6° head-down tilt for 28 days followed by 5-day recovery. Fifty micrograms per day of T3( n = 8) or placebo ( n = 6) were given during bed rest. Serum T3 concentrations increased twofold, whereas thyroid-stimulating hormone was suppressed in treated subjects. T3-treated subjects showed significantly greater negative nitrogen balance and lost more weight ( P = 0.02) and lean mass ( P < 0.0001) than placebo subjects. Protein breakdown (whole body [13C]leucine kinetics) increased 31% in the T3 group but only 8% in the placebo group. T3-treated women experienced greater changes in leucine turnover than men, despite equivalent weight loss. Insulin sensitivity fell by 50% during bed rest in all subjects ( P = 0.005), but growth hormone release and insulin release were largely unaffected. In conclusion, addition of low-dose T3 to the bed rest model of muscle unloading improves the ground-based simulation of spaceflight and unmasks several important gender differences.This study tested the hypothesis that low-dose 3,5, 3-triiodothyronine (T(3)) administration during prolonged bed rest improves the ground-based model of spaceflight. Nine men (36.4 +/- 1. 3 yr) and five women (34.2 +/- 2.1 yr) were studied. After a 5-day inpatient baseline period, subjects were placed at total bed rest with 6 degrees head-down tilt for 28 days followed by 5-day recovery. Fifty micrograms per day of T(3) (n = 8) or placebo (n = 6) were given during bed rest. Serum T(3) concentrations increased twofold, whereas thyroid-stimulating hormone was suppressed in treated subjects. T(3)-treated subjects showed significantly greater negative nitrogen balance and lost more weight (P = 0.02) and lean mass (P < 0.0001) than placebo subjects. Protein breakdown (whole body [(13)C]leucine kinetics) increased 31% in the T(3) group but only 8% in the placebo group. T(3)-treated women experienced greater changes in leucine turnover than men, despite equivalent weight loss. Insulin sensitivity fell by 50% during bed rest in all subjects (P = 0.005), but growth hormone release and insulin release were largely unaffected. In conclusion, addition of low-dose T(3) to the bed rest model of muscle unloading improves the ground-based simulation of spaceflight and unmasks several important gender differences.