Role of environmental vs. metabolic factors in the etiology of obesity: time to focus on the environment

Changes in the serum metabolomics of polycystic ovary syndrome before and after compound oral contraceptive treatment

Background

Polycystic ovary syndrome (PCOS) is both a common endocrine syndrome and a metabolic disorder that results in harm to the reproductive system and whole-body metabolism. This study aimed to investigate differences in the serum metabolic profiles of patients with PCOS compared with healthy controls, in addition to investigating the effects of compound oral contraceptive (COC) treatment in patients with PCOS.

Materials and methods

50 patients with PCOS and 50 sex-matched healthy controls were recruited. Patients with PCOS received three cycles of self-administered COC treatment. Clinical characteristics were recorded, and the laboratory biochemical data were detected. We utilized ultra-performance liquid chromatography-high-resolution mass spectrometry to study the serum metabolic changes between patients with PCOS, patients with PCOS following COC treatment, and healthy controls.

Result

Patients with PCOS who received COC treatment showed significant improvements in serum sex hormone levels, a reduction in luteinising hormone levels, and a significant reduction in the levels of biologically active free testosterone in the blood. Differential metabolite correlation analysis revealed differences between PCOS and healthy control groups in N-tetradecanamide, hexadecanamide, 10E,12Z-octadecadienoic acid, and 13-HOTrE(r); after 3 months of COC treatment, there were significant differences in benzoic acid, organic acid, and phenolamides. Using gas chromatography-mass spectrometry to analyse blood serum in each group, the characteristic changes in PCOS were metabolic disorders of amino acids, carbohydrates, and purines, with significant changes in the levels of total cholesterol, uric acid, phenylalanine, aspartic acid, and glutamate.

Conclusion

Following COC treatment, improvements in sex hormone levels, endocrine factor levels, and metabolic levels were better than in the group of PCOS patients receiving no COC treatment, indicating that COC treatment for PCOS could effectively regulate the levels of sex hormones, endocrine factors, and serum metabolic profiles.

Proposal of a Mathematical Model to Monitor Body Mass over Time in Subjects on a Diet

Nowadays, slimming diet methodology works within a reduction of body mass using a decrease of dietary energy intake. However, there is no suitable method for understanding the dynamic process of body mass metabolic transformation over time. In the present paper, we have developed a biomathematic model to explain the temporal trend of body mass and its variations of people who have undergone a change in their diet using the solving equation of the model. Data relating to sex, age, body mass, and BMI were collected, and the compartmental model used to interpret the body mass trends was constructed by assuming that the mass results from the sum of the metabolic processes: catabolic, anabolic, distributive. The validation of the model was carried out by variance analysis both on the total and individual data sets. The results confirm that the trend of body mass and its variations over time depends on metabolic rates. These are specific to each individual and characterize the distribution of nutritional molecules in the various body districts and the processes catabolic, anabolic, distributive. Body mass and its variations are justified by the metabolic transformations of the nutritional quantities. This would explain why energetically equal diets can correspond to people of different body mass and that energy-different diets can correspond to people of body mass at all similar.

Learned Overeating: Applying Principles of Pavlovian Conditioning to Explain and Treat Overeating

PURPOSE OF REVIEW

This review provides an overview of recent findings relating to the role of Pavlovian conditioning in food cue reactivity, including its application to overeating and weight loss interventions.

RECENT FINDINGS

Both in the laboratory and in real life, cue-elicited appetitive reactivity (e.g., eating desires) can be easily learned, but (long-term) extinction is more difficult. New findings suggest impaired appetitive learning in obesity, which might be causally related to overeating. The clinical analogue of extinction-cue exposure therapy-effectively reduces cue-elicited cravings and overeating. While its working mechanisms are still unclear, some studies suggest that reducing overeating expectancies is important.

SUMMARY

Pavlovian learning theory provides a still undervalued theoretical framework of how cravings and overeating can be learned and how they might be effectively tackled. Future studies should aim to elucidate inter-individual differences in Pavlovian conditioning, study ways to strengthen (long-term) extinction, and investigate the working mechanisms of cue exposure therapy.

Reducing Societal Obesity: Establishing a Separate Exercise Model through Studies of Group Behavior

The past 50 years has brought attention to high and increasing levels of human obesity in most of the industrialized world. The medical profession has noticed, has evaluated, and has developed models for studying, preventing, and reversing obesity. The current model prescribes activity in specific quantities such as days, minutes, heart rates, and footfalls. Although decreased levels of activity have come from changes revolving around built environments and social networks, the existing medical model to lower body weights by increasing activity remains individually prescriptive. It is not working. The study of societal obesity precludes the individual and must involve group behavioral studies. Such studies necessitate acquiring separate tools and, therefore, require a significant change in the evaluation and treatment of obesity. Finding groups with common activities and lower levels of obesity would allow the development of new models of land use and encourage active lifestyles through shared interests.

Does action planning moderate the intention-habit interaction in the exercise domain? A three-way interaction analysis investigation

Both habit strength and action planning have been found to moderate the intention-exercise behaviour relationship, but no research exists that has investigated how habit strength and action planning simultaneously influence this relationship. The present study was designed to explore this issue in a prospective sample of undergraduate students (N = 415): action planning, habit strength, intention, attitudes, subjective norms and perceived behavioural control were assessed at baseline and exercise behaviour was assessed 2 weeks later. Both habit strength and action planning moderated the intention-exercise relationship, with stronger relationship at higher levels of planning or habit strength. Decomposing a significant action planning × habit strength × intention interaction showed that the strength of the intention-exercise relationship progressed linearly through levels of action planning and habit strength. These novel results show that action planning strengthens the intention-habit strength interaction in the exercise domain: exercise interventions should therefore focus on simultaneously bolstering action planning and habit strength.

AFestschriftfor Roland L. Weinsier: Nutrition Scientist, Educator, and Clinician1

Roland L. Weinsier, M.D., Dr.P.H., devoted himself to the fields of nutrition and obesity for more than 35 years. He contributed outstanding work related to the treatment of obesity through dietary and lifestyle change; metabolic/energetic influences on obesity, weight loss, and weight regain; body composition changes accompanying weight loss and regain; the health benefits and risks of weight loss; nutrition education for physicians; and nutrition support of sick patients. He served on the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) National Task Force on Prevention and Treatment of Obesity, as Chair of the University of Alabama at Birmingham's Department of Nutrition Sciences, and as Founder and Director of its NIDDK-funded Clinical Nutrition Research Center. He was a long-time and active member of NAASO, serving in the roles of Councilor, Publications Committee Chair, Continuing Medical Education Course Director, Public Relations Committee Chair, and Membership Committee Co-Chair, to name just a few. He was well respected as a staunch defender of NAASO's scientific integrity in these roles. Sadly, Roland Weinsier died on November 27, 2002. He will be missed and remembered by many as a revered and beloved teacher, mentor, healer, and scholar.

The imperative of human obesity: an ethical reflection

Good health for all has become an accepted international goal. Arguably there have been broad gains in life expectancy over the past century. However, the escalating epidemic of adult obesity, estimated at more than 1 billion worldwide, has become a major public health concern. Obesity affects people of all ages and socioeconomic backgrounds. It is invariably perceived as a product of biological, psychological and social conditions, thereby casting aside its ethical imperatives. Without undermining the role of medicine in managing obesity, this article proposes to discuss the need for nurses to consider relevant ethical principles when supporting people with obesity.

Overweight in adolescents: differences per type of education. Does one size fit all?

OBJECTIVE

To assess the lifestyle and prevalence of overweight among 16- to 18-year-old adolescents attending 4 different types of secondary education (SE).

DESIGN

Cross-sectional school-based survey.

PARTICIPANTS

A community sample of 994 adolescents (body mass index [BMI]: 15-43 kg/m2).

VARIABLES MEASURED

Overweight and obesity were assessed by BMI. Health-related quality of life (HRQL) was assessed using the 36-item short-form (SF-36) questionnaire. The Dutch eating behavior questionnaire was administered. Lifestyle was assessed using the Baecke questionnaire and self-reported activities.

ANALYSIS

Prevalence of overweight, HRQL and lifestyle were assessed per type of education. Gender differences and differences between BMI-categories were analyzed.

RESULTS

Students in Vocational SE were significantly more likely to be overweight (18%) or obese (7.5%) compared to students in other types of SE (chi square-27.0, P < .001). HRQL was significantly lower among obese girls compared to overweight (P = .009) or normal weight girls (P < .01). Obese and overweight adolescents scored higher in restrained eating than their normal weight peers (P < .001) but lower in externally induced eating (P = .001).

CONCLUSIONS AND IMPLICATIONS

Lifestyle and prevalence of overweight and obesity seems to differ between different types of education. This could be of importance when making health policy decisions. Health programs should focus on types of education with the highest prevalence of overweight and obesity and should be tailor-made to the specific needs of the targeted type of education.

Children's dairy intake in the United States: too little, too fat?

OBJECTIVE

To compare reported dairy/calcium intake with intake recommendations and examination of food sources and fat levels of dairy intake in the National Health and Nutrition Examination Survey 1999-2002.

STUDY DESIGN

Dietary, anthropometric, and sociodemographic data for 2- to 18-year-olds (n = 7716) were evaluated to compare intakes of dairy (MyPyramid) and calcium (Adequate Intake [AI]) recommendations. US Department of Agriculture food codes were used to identify mutually exclusive food groups of dairy-contributing foods, which were ranked in descending order proportional to total intake. Complex sample survey Student t tests were used to determine statistical significance among intakes in 4 age groups and between reported and recommended intakes.

RESULTS

Dairy consumption was not significantly different among age groups, but only 2- to 3-year-olds met the MyPyramid recommendation. Calcium intake was significantly different among age groups, and 2- to 8-year-olds met the AI. Intake of flavored milk ranged from 9% to 18%. More than half of the milk consumed by 2- to 3-year-olds was whole milk, and, with the exception of yogurt consumption in 2- to 3-year-olds, children choose to consume more of the highest-fat varieties of cheese, yogurt, ice cream, and dairy-based toppings.

CONCLUSIONS

Dairy and calcium intakes are inadequate in 4- to 18-year-olds. Most children consume the high-fat varieties of milk and dairy products. Focusing nutrition guidance efforts on increasing the intake of the low-fat dairy products, with special emphasis on increasing calcium intake in school-age children and adolescents through flavored low-fat milk products, may be beneficial.

A combined 1H-NMR spectroscopy- and mass spectrometry-based metabolomic study of the PPAR-alpha null mutant mouse defines profound systemic changes in metabolism linked to the metabolic syndrome

The mobilization of triacylglycerides from storage in adipocytes to the liver is a vital response to the fasting state in mammalian metabolism. This is accompanied by a rapid translational activation of genes encoding mitochondrial, microsomal, and peroxisomal beta-oxidation in the liver, in part under the regulation of peroxisome proliferator-activated receptor-alpha (PPAR-alpha). A failure to express PPAR-alpha results in profound metabolic perturbations in muscle tissue as well as the liver. These changes represent a number of deficits that accompany diabetes, dyslipidemia, and the metabolic syndrome. In this study, the metabolic role of PPAR-alpha has been investigated in heart, skeletal muscle, liver, and adipose tissue of PPAR-alpha null mice at 1 mo of age using metabolomics. To maximize the coverage of the metabolome in these tissues, (1)H-NMR spectroscopy, magic angle spinning (1)H-NMR spectroscopy, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry were used to examine metabolites in aqueous tissue extracts and intact tissue. The data were analyzed by the multivariate approaches of principal components analysis and partial least squares. Across all tissues, there was a profound decrease in glucose and a number of amino acids, including glutamine and alanine, and an increase in lactate, demonstrating that a failure to express PPAR-alpha results in perturbations in glycolysis, the citric acid cycle, and gluconeogenesis. Furthermore, despite PPAR-alpha being weakly expressed in adipose tissue, a profound metabolic perturbation was detected in this tissue.

Eating in the absence of hunger: a genetic marker for childhood obesity in prepubertal boys?

OBJECTIVE

Eating in the absence of hunger (EAH) may be a behavioral trait through which obesity-promoting genes promote positive energy balance. The primary aim of this study was to compare children born at high vs. low risk for obesity with respect to EAH at 5 years of age.

RESEARCH METHODS AND PROCEDURES

This was an observational investigation of families enrolled in the University of Pennsylvania and The Children's Hospital of Philadelphia's Infant Growth Study. Five-year-old children born at high (N = 28) or low (N = 25) risk for obesity on the basis of maternal prepregnancy body weight were evaluated at a hospital-based laboratory. Children consumed 11 snack foods ad libitum after consuming an ad libitum dinner and reporting fullness. Parents reported on snack foods at home and their own eating styles. Nutritive sucking at 3 months of age was evaluated by computerized apparatus.

RESULTS

EAH in high-risk boys (mean +/- standard error = 326 +/- 66 kJ] was more than twice that of low-risk boys (mean +/- standard error = 151 +/- 39 kJ), p = 0.03. Among girls, there was a trend for EAH to be associated with increased parental limitations on daughter snack food consumption at home (p = 0.06). EAH was unrelated to 3-month sucking behavior.

DISCUSSION

Genes that promote childhood obesity may partially exert their influence through EAH, an effect that was limited to boys born at risk for obesity. The unique influences of genes and home environment on this trait should be disaggregated in subsequent studies.

Association between socioeconomic status and adiposity in urban Cameroon

BACKGROUND

As the relation between socioeconomic status (SES) and obesity may depend on the stage of development of a country, this relation is assessed in adults from urban Cameroon.

METHODS

A sample comprising 1530 women and 1301 men aged 25 years and above, from 1897 households in the Biyem-Assi health area in the capital of Cameroon, Yaoundé, were interviewed about their household amenities, occupation, and education. Weight, height, and waist circumference were measured and subjects were classified as obese if their BMI>or=30 kg/m2 or overweight if BMI was between 25.0 and 29.9 kg/m2. Abdominal obesity was defined by a waist circumference>or=80 cm in women and>or=94 cm in men.

RESULTS

Of the sample studied 33% of women and 30% of men were overweight (P<0.08), whereas 22% of women and 7% of men were obese (P<0.001). Abdominal obesity was present in 67% of women and 18% of men (P<0.001). After adjusting for age, leisure time physical activity, alcohol consumption, and tobacco smoking, the prevalence of overweight+obesity, obesity, and abdominal obesity increased with quartiles of household amenities in both genders and with occupational level in men.

CONCLUSION

SES is positively associated with adiposity in urban Cameroon after adjusting for confounding factors.

Resting Energy Expenditure: A Better Marker than BMI for BMD in African-American Women

PURPOSE

African-American women tend to be more overweight and to have lower resting energy expenditures (REE) compared with Caucasian women. Weight is associated with bone mineral density (BMD), but the relation between BMD and REE has not been reported.

METHODS

Four hundred postmenopausal African-American women aged 45-87 (yr) from San Diego, CA participated in this community-based cross-sectional study. Body composition (fat mass, lean body mass), bone mineral content (BMC) and BMD of the lumbar spine, hip (femoral neck, greater trochanter, intertrochanter), and total body were measured using dual energy x-ray absorptiometry (DXA). REE was calculated using the Harris-Benedict equation; grip strength was measured by isometric dynamometry.

RESULTS

REE (r range: 0.32-0.79) showed the strongest correlation with spine, total hip, and total body BMC and BMD. In stepwise multiple linear regressions adjusted for age and grip strength, REE explained 15% of the variance in spine BMD, 33% of the variance in total hip, and 32% of the total body BMD variance. REE explained 63% of the total body BMC variance. When body weight replaced REE in the models, weight became the strongest covariate of BMC and BMD but explained 1% less of the variance in spine BMD, 5% less of the variance in total hip BMD, 4% less of the variance in total body BMD, and 3% less of the variances in spine, total hip, and total body BMC than did REE.

CONCLUSION

In this cohort of African-American women, weight explained less of the BMC and BMD variance than REE. Poor energy economy may contribute to being overweight and may explain the lower rates of osteoporosis observed in African-American women.

Ethnic comparison of weight loss in the Trial of Nonpharmacologic Interventions in the Elderly

OBJECTIVE

To compare weight loss in blacks and whites in the Trial of Nonpharmacologic Interventions in the Elderly (TONE).

RESEARCH METHODS AND PROCEDURES

TONE enrolled 421 overweight white and 164 overweight black adults, 60 to 79 years old, with blood pressure well-controlled on a single, antihypertensive drug. Drug therapy withdrawal was attempted 3 months after randomization to counseling for weight loss, sodium reduction, both weight loss and sodium reduction, or to usual care, with follow-up for 15 to 36 months after enrollment. Statistical procedures included repeated measures analysis of covariance and logistic and proportional hazards regression.

RESULTS

In the weight-loss condition, net weight change (in kilograms) was -2.7 in blacks and -5.9 in whites (p < 0.001; ethnic difference, p = 0.0002) at 6 months and -2.0 (p < 0.05) in blacks and -4.9 (p < 0.001) in whites at the end of follow-up (ethnic difference, p = 0.007). In weight/sodium, net weight change was -2.1 (p < 0.01) in blacks and -2.8 (p < 0.001) in whites at 6 months, and -1.9 in blacks and -1.7 in whites at the end of follow-up (p < 0.05; ethnic difference, p > 0.5). Exploratory analyses suggested a more favorable pattern of weight change in blacks than in whites from 6 months onward. There was no ethnic difference in blood pressure outcomes.

DISCUSSION

Whites lost more weight than blacks without, but not with, a concurrent focus on sodium reduction.