A Better Index of Body Adiposity Bergman, Richard N.; Stefanovski, Darko; Buchanan, Thomas A. ...
Obesity,
20/May , Volume:
19, Issue:
5
Journal Article
Peer reviewed
Open access
Obesity is a growing problem in the United States and throughout the world. It is a risk factor for many chronic diseases. The BMI has been used to assess body fat for almost 200 years. BMI is known ...to be of limited accuracy, and is different for males and females with similar %body adiposity. Here, we define an alternative parameter, the body adiposity index (BAI = ((hip circumference)/((height)1.5)–18)). The BAI can be used to reflect %body fat for adult men and women of differing ethnicities without numerical correction. We used a population study, the “BetaGene” study, to develop the new index of body adiposity. %Body fat, as measured by the dual‐energy X‐ray absorptiometry (DXA), was used as a “gold standard” for validation. Hip circumference (R = 0.602) and height (R = −0.524) are strongly correlated with %body fat and therefore chosen as principal anthropometric measures on which we base BAI. The BAI measure was validated in the “Triglyceride and Cardiovascular Risk in African‐Americans (TARA)” study of African Americans. Correlation between DXA‐derived %adiposity and the BAI was R = 0.85 for TARA with a concordance of C_b = 0.95. BAI can be measured without weighing, which may render it useful in settings where measuring accurate body weight is problematic. In summary, we have defined a new parameter, the BAI, which can be calculated from hip circumference and height only. It can be used in the clinical setting even in remote locations with very limited access to reliable scales. The BAI estimates %adiposity directly.
Metformin can decrease adiposity and ameliorate obesity-related comorbid conditions, including abnormalities in glucose homeostasis in adolescents, but there are few data evaluating the efficacy of ...metformin among younger children. Our objective was to determine whether metformin treatment causes weight loss and improves obesity-related comorbidities in obese children, who are insulin-resistant.
This study was a randomized double-blind placebo-controlled trial consisting of 100 severely obese (mean BMI 34.6 ± 6.6 kg/m(2)) insulin-resistant children aged 6-12 years, randomized to 1,000 mg metformin (n = 53) or placebo (n = 47) twice daily for 6 months, followed by open-label metformin treatment for 6 months. All children and their parents participated in a monthly dietitian-administered weight-reduction program.
Eighty-five percent completed the 6-month randomized phase. Children prescribed metformin had significantly greater decreases in BMI (difference -1.09 kg/m(2), CI -1.87 to -0.31, P = 0.006), body weight (difference -3.38 kg, CI -5.2 to -1.57, P < 0.001), BMI Z score (difference between metformin and placebo groups -0.07, CI -0.12 to -0.01, P = 0.02), and fat mass (difference -1.40 kg, CI -2.74 to -0.06, P = 0.04). Fasting plasma glucose (P = 0.007) and homeostasis model assessment (HOMA) insulin resistance index (P = 0.006) also improved more in metformin-treated children than in placebo-treated children. Gastrointestinal symptoms were significantly more prevalent in metformin-treated children, which limited maximal tolerated dosage in 17%. During the 6-month open-label phase, children treated previously with placebo decreased their BMI Z score; those treated continuously with metformin did not significantly change BMI Z score further.
Metformin had modest but favorable effects on body weight, body composition, and glucose homeostasis in obese insulin-resistant children participating in a low-intensity weight-reduction program.
Both human linkage studies and MC3R knockout mouse models suggest that the MC3R may play an important role in energy homeostasis. Here we show that among 355 overweight and nonoverweight children, ...8.2% were double homozygous for a pair of missense MC3R sequence variants (Thr6Lys and Val81Ile). Such children were significantly heavier (BMI and BMI SD score: P < 0.0001), had more body fat (body fat mass and percentage fat mass: P < 0.001), and had greater plasma leptin (P < 0.0001) and insulin concentrations (P < 0.001) and greater insulin resistance (P < 0.008) than wild-type or heterozygous children. Both sequence variants were more common in African-American than Caucasian children. In vitro expression studies found the double mutant MC3R was partially inactive, with significantly fewer receptor binding sites, decreased signal transduction, and less protein expression. We conclude that diminished MC3R expression in this double MC3R variant may be a predisposing factor for excessive body weight gain in children.
Context: Some studies suggest the presence of metabolic syndrome before adulthood may identify those at high risk for later cardiovascular morbidity, but there are few data examining the reliability ...of pediatric metabolic syndrome.
Objective: To examine the short- and long-term stability of pediatric metabolic syndrome.
Design: Metabolic syndrome was defined as having at least three of the following: waist circumference, blood pressure, and fasting serum triglycerides in the 90th or higher percentile for age/sex; high-density lipoprotein-cholesterol 10th or lower percentile for age/sex; and fasting serum glucose of at least 100 mg/dl. Short-term metabolic syndrome stability (repeated measurements within 60 d) was assessed in obese youth ages 6–17 yr. Long-term metabolic syndrome stability (repeated measurements more than 1.5 yr apart) was studied in 146 obese and nonobese children age 6–12 yr at baseline.
Patients and Setting: Convenience samples of obese and nonobese youth ages 6–17 yr participating in research studies were collected at a clinical research hospital.
Results: Short-term metabolic syndrome stability (repeat measurements performed 19.7 ± 13.1 d apart) was assessed in 220 children. The diagnosis of metabolic syndrome was unstable in 31.6% of cases. At their short-term follow-up visit, incidence of metabolic syndrome among participants who did not have metabolic syndrome at baseline was 24%. In the long term (repeat measurements performed 5.6 ± 1.9 yr apart), the diagnosis of metabolic syndrome was unstable in 45.5% of cases.
Conclusions: Cutoff-point-based definitions for pediatric metabolic syndrome have substantial instability in the short and long term. The value of making a cutoff-point-based diagnosis of metabolic syndrome during childhood or adolescence remains in question.
Cut-point-based definitions for pediatric metabolic syndrome have substantial instability in the short- and long-term that may limit the value of making this diagnosis.
Summary
Context Both obesity (body mass index, BMI ≥ 30 kg/m2) and Black race are associated with a higher risk of vitamin D deficiency and secondary hyperparathyroidism. We hypothesized the risk of ...hypovitaminosis D would therefore be extraordinarily high in obese Black adults.
Objective To study the effects of race and adiposity on 25‐hydroxyvitamin D 25(OH)D and parathyroid hormone (iPTH).
Design, Setting and Participants Cross‐sectional study of 379 Black and White adults from the Washington D.C. area. BMI ranged from 19·9 to 58·2 kg/m2.
Main Outcome Measures Prevalence of hypovitaminosis D 25(OH)D < 37·5 nmol/l and secondary hyperparathyroidism 25(OH)D < 37·5 nmol/l with iPTH > 4·2 pmol/l.
Results Obese Black subjects had lower mean 25(OH)D, 40·3 (SD, 20·3) nmol/l, compared with obese Whites, 64·5 (29·7), P < 0·001, nonobese Blacks, 53·3 (26·0), P = 0·0025 and nonobese Whites, 78·0 (33·5), P < 0·001. The prevalence of hypovitaminosis D increased with increasing BMI, and was greater (P < 0·001) in Blacks than Whites within all BMI categories examined. Among subjects with BMI ≥ 35 kg/m2, 59% of Blacks vs 18% of Whites had hypovitaminosis D (odds ratio 6·5, 95% confidence interval 3·0–14·2). iPTH was negatively correlated with 25(OH)D (r = –0·31, P < 0·0001), suggesting those with hypovitaminosis D had clinically important vitamin D deficiency with secondary hyperparathyroidism. For secondary hyperparathyroidism 35·2% of Blacks met the criteria, compared to 9·7% of Whites (OR 3·6, CI 1·5–98·8).
Conclusions Obese Black Americans are at particularly high risk for vitamin D deficiency and secondary hyperparathyroidism. Physicians should consider routinely supplementing such patients with vitamin D or screening them for hypovitaminosis D.
A prospective study of holiday weight gain Yanovski, J A; Yanovski, S Z; Sovik, K N ...
New England journal of medicine/The New England journal of medicine,
03/2000, Volume:
342, Issue:
12
Journal Article
Peer reviewed
Open access
It is commonly asserted that the average American gains 5 lb (2.3 kg) or more over the holiday period between Thanksgiving and New Year's Day, yet few data support this statement.
To estimate actual ...holiday-related weight variation, we measured body weight in a convenience sample of 195 adults. The subjects were weighed four times at intervals of six to eight weeks, so that weight change was determined for three periods: preholiday (from late September or early October to mid-November), holiday (from mid-November to early or mid-January), and postholiday (from early or mid-January to late February or early March). A final measurement of body weight was obtained in 165 subjects the following September or October. Data on other vital signs and self-reported health measures were obtained from the patients in order to mask the main outcome of interest.
The mean (+/-SD) weight increased significantly during the holiday period (gain, 0.37+/-1.52 kg; P<0.001), but not during the preholiday period (gain, 0.18+/-1.49 kg; P=0.09) or the postholiday period (loss, 0.07+/-1.14 kg; P=0.36). As compared with their weight in late September or early October, the study subjects had an average net weight gain of 0.48+/-2.22 kg in late February or March (P=0.003). Between February or March and the next September or early October, there was no significant additional change in weight (gain, 0.21 kg+/-2.3 kg; P=0.13) for the 165 participants who returned for follow-up.
The average holiday weight gain is less than commonly asserted. Since this gain is not reversed during the spring or summer months, the net 0.48-kg weight gain in the fall and winter probably contributes to the increase in body weight that frequently occurs during adulthood.
Background: Little is known about how simpler and more available methods to measure change in body fatness compare with criterion methods such as dual-energy X-ray absorptiometry (DXA) in children. ...Objective: Our objective was to determine the ability of air-displacement plethysmography (ADP) and formulas based on triceps skinfold thickness (TSF) and bioelectrical impedance analysis (BIA) to estimate changes in body fat over time in children. Design: Eighty-six nonoverweight and overweight boys (n = 34) and girls (n = 52) with an average age of 11.0 ± 2.4 y underwent ADP, TSF measurement, BIA, and DXA to estimate body fatness at baseline and 1 ± 0.3 y later. Recent equations were used to estimate percentage body fat by TSF measurement (Dezenberg equation) and by BIA (Suprasongsin and Lewy equations). Percentage body fat estimates by ADP, TSF measurement, and BIA were compared with those by DXA. Results: All methods were highly correlated with DXA (P < 0.001). No mean bias for estimates of percentage body fat change was found for ADP (Siri equation) compared with DXA for all subjects examined together, and agreement between body fat estimation by ADP and DXA did not vary with race or sex. Magnitude bias was present for ADP relative to DXA (P < 0.01). Estimates of change in percentage body fat were systematically overestimated by BIA equations (1.37 ± 6.98%; P < 0.001). TSF accounted for only 13% of the variance in percentage body fat change. Conclusion: Compared with DXA, there appears to be no noninvasive and simple method to measure changes in children's percentage body fat accurately and precisely, but ADP performed better than did TSF or BIA. ADP could prove useful for measuring changes in adiposity in children.
Some data suggest that increasing calcium intake may help prevent weight gain.
To test the hypothesis that calcium supplementation can prevent weight gain in persons who are overweight or obese.
...Randomized, placebo-controlled trial. Randomization was computer-generated, and allocation was assigned by pharmacy personnel who prepared intervention and placebo capsules. Participants, providers, and those who assessed outcomes were blinded to study group assignment.
Single research center.
340 overweight (body mass index BMI, 25 to <30 kg/m(2)) and obese (BMI > or =30 kg/m(2)) adults (mean age, 38.8 years SD, 10.5).
Calcium carbonate (elemental calcium, 1500 mg/d) (n = 170) or placebo (n = 170) with meals for 2 years.
Changes in body weight and fat mass (primary outcomes).
Seventy-five percent of participants completed the trial (78% received calcium; 73% received placebo). There were no statistically or clinically significant differences between the calcium and placebo groups in change in body weight (difference, 0.02 kg 95% CI, -1.64 to 1.69 kg; P = 0.98), BMI (difference, 0.32 kg/m(2) CI, -0.41 to 1.02 kg/m(2); P = 0.39), or body fat mass (difference, 0.39 kg CI, -1.04 to 1.92 kg; P = 0.55). Parathyroid hormone concentrations decreased in the calcium group compared with the placebo group (difference, -0.71 pmol/L CI, -1.28 to -0.13 pmol/L).
The study took place at a research center, and its sample was mostly women.
Dietary supplementation with elemental calcium, 1500 mg/d, for 2 years had no statistically or clinically significant effects on weight in overweight and obese adults. Calcium supplementation is unlikely to have clinically significant efficacy as a preventive measure against weight gain in such patients.
Total body size and central fat distribution are important determinants of insulin resistance. The BMI and waist circumference (WC) thresholds in African Americans that best predict insulin ...resistance are unknown. Our goal was to determine the BMI and WC values in African Americans, which optimally predict insulin resistance. The subjects were African Americans (68 men, 63 women), aged 35 ± 8 years (mean ± s.d.), with a BMI of 30.9 ± 7.5, in the range of 18.5–54.7 kg/m2, and with a WC of 98 ± 18, in the range of 69–173 cm. Insulin resistance was defined by the lowest tertile of the insulin sensitivity index (SI). The Youden index was calculated to determine the WC and BMI thresholds that predict insulin resistance with an optimal combination of sensitivity and specificity. In men the thresholds that optimally predicted insulin resistance were a BMI ≥30 kg/m2 or a WC ≥102 cm. For women, insulin resistance was best predicted by a BMI ≥32 kg/m2 or a WC ≥98 cm. In African Americans, insulin resistance (in men) was best predicted by a WC ≥102 cm, and in women by a WC ≥98 cm, or by a BMI value that fell in the obese category (men: ≥30 kg/m2, women: ≥32 kg/m2).
Objective: To study the safety, tolerability, and potential efficacy of orlistat in adolescents with obesity and its comorbid conditions.
Research Methods and Procedures: We studied 20 adolescents ...(age, 14.6 ± 2.0 years; body mass index, 44.1 ± 12.6 kg/m2). Subjects were evaluated before and after taking orlistat (120 mg three times daily) and a multivitamin for 3 months. Subjects were simultaneously enrolled in a 12‐week program emphasizing diet, exercise, and strategies for behavior change.
Results: Participants who completed treatment (85%) reported taking 80% of prescribed medication. Adverse effects were generally mild, limited to gastrointestinal effects observed in adults, and decreased with time. Three subjects required additional vitamin D supplementation despite the prescription of a daily multivitamin containing vitamin D. Weight decreased significantly (−4.4 ± 4.6 kg, p < 0.001; −3.8 ± 4.1% of initial weight), as did body mass index (−1.9 ± 2.5 kg/m2; p < 0.0002). Total cholesterol (−21.3 ± 24.7 mg/dL; p < 0.001), low‐density lipoprotein‐cholesterol (−17.3 ± 15.8 mg/dL; p < 0.0001), fasting insulin (−13.7 ± 19.0 μU/mL; p < 0.02), and fasting glucose (−15.4 ± 7.4 mg/dL; p < 0.003) were also significantly lower after orlistat. Insulin sensitivity, assessed by a frequently sampled intravenous glucose‐tolerance test, improved significantly (p < 0.02).
Discussion: We conclude that, in adolescents, short‐term treatment with orlistat, in the context of a behavioral program, is well‐tolerated and has a side‐effect profile similar to that observed in adults, but its true benefit versus conventional therapy remains to be determined in placebo‐controlled trials.
PDF
