Obesity: Overview of Weight Management

IntroductionObesity is a chronic illness that requires a multifaceted personalized treatment approach.Methods & FindingsUsing current guidelines and recent studies in weight management, this article reviews the multiple components of weight management: lifestyle intervention (dietary intervention, physical activity, and behavioral interventions), pharmacotherapy, endoscopic procedures, and surgical procedures. This review briefly discusses specific diets and dietary strategies, compensatory mechanisms acting against weight loss, recent changes to Food and Drug Administration approved antiobesity medications, and technological advances in weight management delivery.ConclusionCurrent literature is lacking large studies on the safety and efficacy of combination therapies involving pharmacotherapy plus 1 or more procedures.     

Association of maternal lifestyles including smoking during pregnancy with childhood obesity

Objective: To examine the extent to which maternal smoking during early pregnancy and other prepregnancy lifestyle habits are associated with obesity and overweight in 5‐year‐old Japanese children. Research Method and Procedures: We studied 1417 mother‐child pairs enrolled in Project Enzan—a prospective cohort study. The dependent variables, childhood overweight and obesity, were defined with an international cut‐off value. Maternal smoking during early pregnancy and other prepregnancy lifestyle habits were used as independent variables. Results: Maternal smoking habits were associated with overweight in the 5‐year‐old children [adjusted odds ratio (OR): 2.15; 95% confidence interval (CI): 1.12 to 4.11]. Maternal sleep duration of ≥8 h/d negatively affected childhood overweight (adjusted OR: 0.71; 95% CI: 0.49 to 1.04). Children whose mothers skipped breakfast were likely to become overweight (adjusted OR: 1.78; 95% CI: 1.14 to 2.77). The results of childhood obesity analysis were similar to those of childhood overweight analysis. Discussion: The results of this study suggest that there are effects of smoking during early pregnancy and other maternal lifestyle habits on the onset of childhood obesity in Japan. Therefore, interventions in maternal lifestyle habits are required to prevent childhood obesity, and these interventions should be initiated before pregnancy.     

Male inclusion in randomized controlled trials of lifestyle weight loss interventions

The prevalence of obesity is similar for men (32.2%) and women (35.5%). It has been assumed that lifestyle weight loss interventions have been developed and tested in predominately female samples, but this has not been systematically investigated. The aim of this review was to investigate total and ethnic male inclusion in randomized controlled trials of lifestyle interventions. PUBMED, MEDLINE, and PSYCHINFO were searched for randomized controlled trials of lifestyle weight loss interventions (N = 244 studies with a total of 95,207 participants) published in the last 10 years (1999-2009). A trial must be in English, included weight loss as an outcome, and tested a dietary, exercise, and/or other behavioral intervention for weight loss. Results revealed samples were on average 27% male vs. 73% female (P < 0.001). Trials recruiting a diseased sample included a larger proportion of males than those not targeting a disease (35% vs. 21%; P < 0.001). About 32% of trials used exclusively female samples, whereas only 5% used exclusively male samples (P < 0.001). No studies in the past 10 years specifically targeted minority males. Ethnic males identified composed 1.8% of total participants in US studies. Only 24% of studies that underrepresented males provided a reason. Males, especially ethnic males, are underrepresented in lifestyle weight loss trials.     

Effects of Growth Hormone Administration in Human Obesity

Objective: To summarize the reports in the literature regarding the effect of growth hormone (GH) treatment of obesity. Research Methods and Procedures: Clinical trials of GH treatment of obese adults were reviewed and summarized. Specifically, information regarding the effects of GH on body fat and body fat distribution, glucose tolerance/insulin resistance, and adverse consequences of treatment were recorded. Results: GH administered together with hypocaloric diets did not enhance fat loss or preserve lean tissue mass. No studies provided strong evidence for an independent beneficial effect of GH on visceral adiposity. In all but one study, glucose tolerance during GH treatment suffered relative to placebo. Conclusion: The bulk of studies indicate little or no beneficial effects of GH treatment of obesity despite the low serum GH concentrations associated with obesity.     

A Food and Drug Administration-approved Asthma Therapeutic Agent Impacts Amyloid β in the Brain in a Transgenic Model of Alzheimer Disease

Interfering with the assembly of Amyloid β (Aβ) peptides from monomer to oligomeric species and fibrils or promoting their clearance from the brain are targets of anti-Aβ-directed therapies in Alzheimer disease. Here we demonstrate that cromolyn sodium (disodium cromoglycate), a Food and Drug Administration-approved drug already in use for the treatment of asthma, efficiently inhibits the aggregation of Aβ monomers into higher-order oligomers and fibrils in vitro without affecting Aβ production. In vivo, the levels of soluble Aβ are decreased by over 50% after only 1 week of daily intraperitoneally administered cromolyn sodium. Additional in vivo microdialysis studies also show that this compound decreases the half-life of soluble Aβ in the brain. These data suggest a clear effect of a peripherally administered, Food and Drug Administration-approved medication on Aβ economy, supporting further investigation of the potential long-term efficacy of cromolyn sodium in Alzheimer disease.     

Biology and therapy of fibromyalgia. New therapies in fibromyalgia

Fibromyalgia is a chronic, musculoskeletal pain condition that predominately affects women. Although fibromyalgia is common and associated with substantial morbidity and disability, there are no US Food and Drug Administration-approved treatments. However, progress has been made in identifying pharmacological and non-pharmacological treatments for fibromyalgia. Recent pharmacological treatment studies have focused on selective serotonin and norepinephrine reuptake inhibitors, which enhance serotonin and norepinephrine neurotransmission in the descending pain pathways and lack many of the adverse side effects associated with tricyclic medications. Promising results have also been reported for medications that bind to the α₂δ subunit of voltage-gated calcium channels, resulting in decreased calcium influx at nerve terminals and subsequent reduction in the release of several neurotransmitters thought to play a role in pain processing. There is also evidence to support exercise, cognitive behavioral therapy, education, and social support in the management of fibromyalgia. It is likely that many patients would benefit from combinations of pharmacological and non-pharmacological treatments, but more study is needed.     

Passing the Red Pen: EvoS Journal Offers an Early Education in Peer Review

EvoS Journal: The Journal of the Evolutionary Studies Consortium is the open-access, peer-reviewed journal borne of the EvoS (Evolutionary Studies) Consortium movement. The journal has two separate, yet related goals: to publish scholarly articles regarding the intersection of higher education and evolutionary theory, and to publish articles written and reviewed by undergraduates that incorporate an evolutionary perspective. Undergraduates who publish and review for EvoS Journal get the chance to see their work published alongside that of experts within the field of evolutionary studies, and to see the interdisciplinary and widespread applications of evolutionary theory to human life and beyond. The current study examines whether the interdisciplinary nature of EvoS Journal and its initiation of students into the peer-review process set EvoS Journal apart from more traditional undergraduate journals. EvoS Journal was compared to other journals listed by the Council for Undergraduate Research. While EvoS Journal mirrors many traditional undergraduate journals in their employment of student reviewers and publishing work originating from any U.S. institution, it differs by both its interdisciplinary focus and by serving as an outlet for both student and professional publications. The implications are discussed in terms of the benefits of interdisciplinary and peer-review training to students in the classroom, including improvements in writing, interpersonal relations, and real-world skills.     

Prevalence and Covariates of Obesity in Lebanon: Findings from the First Epidemiological Study

Objective: To estimate the prevalence of overweight and obesity and examine associated covariates in the Lebanese population. Research Methods and Procedures: A cross‐sectional survey of a representative sample of 2104 individuals, 3 years of age and older. Anthropometric measurements and dietary assessments were conducted following standard methods and techniques. Overweight and obesity (classes I to III) were defined according to internationally standardized criteria for classification of BMI. Results: For children 3 to 19 years of age, prevalence rates of overweight and obesity were higher overall for boys than girls (22.5% vs. 16.1% and 7.5% vs. 3.2%, respectively). For adult men and women (age ≥ 20 years), the prevalence of overweight was 57.7% and 49.4%, respectively. In contrast, obesity (BMI ≥ 30 kg/m²) was higher overall among women (18.8%) than men (14.3%), a trend that became more evident with increasing obesity class. BMI, percentage of body fat, and waist circumference increased to middle age and declined thereafter. Whereas lack of exercise associated significantly with obesity among children, obesity in older adults was more prevalent among the least educated, nonsmokers, and those reporting a family history of obesity. Discussion: The results from this national population‐based study in Lebanon show high prevalence rates of overweight and obesity comparable with those observed in developed countries such as the United States. While further studies are needed to examine the underlying social and cultural factors associated with lifestyle and nutritional habits, now is the time to institute multicomponent interventions promoting physical activity and weight control nationwide.     

American Association of Clinical Endocrinology Clinical Practice Guideline for the Diagnosis and Management of Nonalcoholic Fatty Liver Disease in Primary Care and Endocrinology Clinical Settings: Co-Sponsored by the American Association for the Study of Liver Diseases (AASLD)

ObjectiveTo provide evidence-based recommendations regarding the diagnosis and management of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) to endocrinologists, primary care clinicians, health care professionals, and other stakeholders.MethodsThe American Association of Clinical Endocrinology conducted literature searches for relevant articles published from January 1, 2010, to November 15, 2021. A task force of medical experts developed evidence-based guideline recommendations based on a review of clinical evidence, expertise, and informal consensus, according to established American Association of Clinical Endocrinology protocol for guideline development.Recommendation SummaryThis guideline includes 34 evidence-based clinical practice recommendations for the diagnosis and management of persons with NAFLD and/or NASH and contains 385 citations that inform the evidence base.ConclusionNAFLD is a major public health problem that will only worsen in the future, as it is closely linked to the epidemics of obesity and type 2 diabetes mellitus. Given this link, endocrinologists and primary care physicians are in an ideal position to identify persons at risk on to prevent the development of cirrhosis and comorbidities. While no U.S. Food and Drug Administration-approved medications to treat NAFLD are currently available, management can include lifestyle changes that promote an energy deficit leading to weight loss; consideration of weight loss medications, particularly glucagon-like peptide-1 receptor agonists; and bariatric surgery, for persons who have obesity, as well as some diabetes medications, such as pioglitazone and glucagon-like peptide-1 receptor agonists, for those with type 2 diabetes mellitus and NASH. Management should also promote cardiometabolic health and reduce the increased cardiovascular risk associated with this complex disease.     

RECENT ORNITHOLOGICAL LITERATURE

Beginning in 1983 (Auk 100, Ibis 125) the AOU and BOU combined their Recent Literature sections, to publish a single supplement of ornithological literature to which members of both unions contribute. The RAOU joined this partnership in 1987 (Emu 87). The AOU covers journals published in the Americas and The Philippines. The BOU covers journals published in Europe, Africa, and mainland Asia. The RAOU covers journals published in Australasia and other island nations of the Pacific. More than 150 volunteers scan about 650 titles and contribute abstracts regularly. Authors' addresses are included, if the journal lists them, to facilitate communication between readers and authors Recent Ornithological Literature strives for comprehensive coverage of the world's periodical literature of interest to persons studying wild birds. Readers are encouraged to consult the “List of Journals Scanned” published annually in the October supplement and to make recommendations for increasing journal coverage.     

Long-term obesity levels in female OLETF rats following time-specific post-weaning food restriction

Obesity and the metabolic syndrome represent serious health threats affecting increasing numbers of individuals, with females being more affected than males and with growing incidence among children and adolescents. In the present study, we used the OLETF rat model of early-onset obesity to examine the influence of different timing of food restriction on long-term obesity levels in females. Food restriction took place at different time windows: from weaning until postnatal day (PND) 45 (early); from weaning until PND90 (chronic); or from PND45 until PND70 (late). Follow-up continued until PND90. During and after the termination of the diet-restriction period, we focused on peripheral adiposity-related measures such as fat pad weight (brown, retroperitoneal and inguinal); inguinal adipocyte size and number; and leptin, oxytocin and glucose levels. We also examined body weight, feeding efficiency, spontaneous intake after release from diet-restriction, and plasma creatinine levels and estrous cycle characteristics as a result of the chronic diet. The results suggest that while food restriction produced significant weight and adiposity loss, OLETF females presented poor weight loss retention after the early and late short-term diets. The estrous cycle structure and time of first estrous of the OLETF rats were normalized by chronic food restriction. Females responded to early food restriction in a different manner than males did in previous studies, further emphasizing the importance of sex-appropriate approaches in the investigation and treatment of the pathologies related to obesity and the metabolic syndrome.     

Lifestyle Intervention Decreases Urine Trimethylamine N‐Oxide Levels in Prepubertal Children with Obesity

Objective

Early lifestyle interventions in children with obesity decrease risk of obesity and metabolic disorders during adulthood. This study aimed to identify metabolic signatures associated with lifestyle intervention in urine samples from prepubertal children with obesity.

Methods

Thirty‐four prepubertal children with obesity were studied before and after a 6‐month lifestyle intervention program, and anthropometric, metabolic, and nutritional variables were collected. A nuclear magnetic resonance approach was applied to obtain the metabolomic profile from urine samples. Partial least squares‐discriminant analysis (PLS‐DA) was used to achieve group classification and variable importance on projection (VIP) for biomarker selection.

Results

The intervention reduced caloric intake by 10% (P < 0.05) and BMI standard deviation score by 0.47 SD (P < 0.001). PLS‐DA identified trimethylamine N‐oxide (TMAO, VIP = 2.21) as the metabolite with the highest discrimination properties between groups. Urine TMAO levels were reduced after the intervention (P < 0.05). TMAO is a biomarker of cardiovascular disease risk and is a product of gut microbiota‐dependent metabolism of certain dietary compounds, including choline. Notably, changes in TMAO levels after the intervention did not correlate to differences in choline intake but were inversely associated with fiber intake (P < 0.05).

Conclusions

These results indicate that lifestyle intervention decreases TMAO levels in children with obesity.

     

Lifestyle interventions in the management of hypertension: a survey based on the opinion of 105 practitioners

Background Lifestyle interventions in the management of hypertension were beneficial in published studies. ObjectiveTo evaluate (1) which lifestyle recommendations are given by physicians and to what extent the possibility of drug-induced hypertension is addressed; (2) to study the characteristics of the physicians who more often perform lifestyle interventions. MethodsGeneral practitioners in the area of Dordrecht were asked whether or not they included lifestyle advice in the management of their patients' hypertension. ResultsOf the 176 physicians invited, 105 consented to take part. Measures to reduce body weight, stopping smoking, and physical exercise advice were given by 94, 92, and 92% of the physicians, respectively. Advice on psychological relaxation and reducing liquorice (Dutch: drop) intake was only given by 23 and 32%. Rural physicians were more active: they more often recommended quitting smoking (p<0.02), reducing weight (p<0.02), and participating in sporting activities (p<0.02). And so were older physicians: they more often recommended starting low-calorie diets (p<0.05), stopping liquorice consumption (p<0.04) and emphasised drug compliance (p<0.02). Increased blood pressure as a side effect of concomitant medications, other than nonsteroidal anti-inflammatory drugs and oral contraceptives, was virtually never addressed. Conclusions(1) Advice to reduce body weight, stop smoking, and increase physical exercise are the only lifestyle recommendations routinely given, (2) rural physicians and older physicians were more active in giving non-drug treatments, (3) increased blood pressure as a side effect of medications was virtually never addressed. (Neth Heart J 2009;17:9-12.)     

Lifestyle Interventions Limit Gestational Weight Gain in Women with Overweight or Obesity: LIFE‐Moms Prospective Meta‐Analysis

Objective

This study aimed to evaluate the effects of varied lifestyle intervention programs designed to ameliorate excess gestational weight gain (GWG) in pregnant women with overweight or obesity compared with standard care, including effects on pregnancy outcomes.

Methods

Seven clinical centers conducted separate randomized clinical trials to test different lifestyle intervention strategies to modify GWG in diverse populations. Eligibility criteria, specific outcome measures, and assessment procedures were standardized across trials. The results of the separate trials were combined using an individual‐participant data meta‐analysis.

Results

For the 1,150 women randomized, the percent with excess GWG per week was significantly lower in the intervention group compared with the standard care group (61.8% vs. 75.0%; odds ratio [95% CI]: 0.52 [0.40 to 0.67]). Total GWG from enrollment to 36 weeks' gestation was also lower in the intervention group (8.1 ± 5.2 vs. 9.7 ± 5.4 kg; mean difference: ?1.59 kg [95% CI:?2.18 to ?0.99 kg]). The results from the individual trials were similar. The intervention and standard care groups did not differ in preeclampsia, gestational diabetes, cesarean delivery, or birth weight.

Conclusions

Behavioral lifestyle interventions focusing primarily on diet and physical activity among women with overweight and obesity resulted in a significantly lower proportion of women with excess GWG. This modest beneficial effect was consistent across diverse intervention modalities in a large, racially and socioeconomically diverse US population of pregnant women.

     

Dietary effects on fatty acid composition in muscle tissue of juvenile European eel, <Emphasis Type="Italic">Anguilla anguilla</Emphasis> (L.)

The role of intracontinental migration patterns of European eel (Anguilla anguilla) receives more and more recognition in both ecological studies of the European eel and possible management measures, but small-scale patterns proved to be challenging to study. We experimentally investigated the suitability of fatty acid trophic markers to elucidate the utilization of feeding habitats. Eight groups of juvenile European eels were fed on eight different diets in a freshwater recirculation system at 20°C for 56 days. Three groups were fed on freshwater diets (Rutilus rutilus, Chironomidae larvae, and Gammarus pulex) and four groups were reared on diets of a marine origin (Clupea harengus, Crangon crangon, Mysis spec., and Euphausia superba) and one on commercial pellets used in eel aquaculture. Fatty acid composition (FAC) of diets differed significantly with habitat. FAC of eel muscle tissue seemed to be rather insensitive to fatty acids supplied with diet, but the general pattern of lower n3:n6 and EPA:ARA ratios in freshwater prey organisms could be traced in the respective eels. Multivariate statistics of the fatty acid composition of the eels resulted in two distinct groups representing freshwater and marine treatments. Results further indicate the capability of selectively restraining certain fatty acids in eel, as e.g. the n3:n6 ratio in all treatments was <4, regardless of dietary n3:n6. In future studies on wild eel, these measures can be used to elucidate the utilization of feeding habitats of individual European eel.     

Toenail mercury levels positively correlate with obesity and abdominal obesity among Korean adults

BackgroundAlthough previous studies have shown that short-term exposure to mercury is associated with obesity, it should be noted that mercury is not easily released and that it constantly accumulates in the body. However, few studies have explored the association between chronic mercury exposure and obesity. This study aimed to examine the association between chronic mercury exposure and obesity in Korean adults.MethodsThe study used baseline data from the Trace Element Study of Korean Adults in Yeungnam area. A total of 495 participants aged 40–69 years who provided the required information (demographic, diet, lifestyle, toenail mercury levels, and health examination results) were included. Toenail mercury levels were measured using neutron-activation analysis. Body mass index and waist circumference were obtained from medical examination. Multivariable-adjusted logistic regression and restricted cubic spline regression were used in the analysis.ResultsIn the fully adjusted logistic regression models, participants with the highest toenail mercury levels had a higher prevalence of obesity (odds ratio [OR]: 3.26, 95 % confidence interval [CI]: 1.79–5.93) and abdominal obesity (OR: 2.30, 95 % CI: 1.15–4.59). In the cubic spline regression model, linear relationships were confirmed between increased toenail mercury levels and higher prevalence of obesity and abdominal obesity (all p > 0.05 for nonlinearity).ConclusionsIn summary, chronic mercury exposure was associated with higher prevalence of obesity and abdominal obesity in Korean adults. Therefore, the development of public health interventions against environmental exposure of foods is required to manage and prevent obesity.     

Plasma levels of resistin-like molecule beta in humans

Background: Resistin-like molecules (RELM) are expressed in many tissues and among those, RELMβ is most abundantly expressed in the colon. Based on animal studies, RELMβ is induced by high fat diets, obesity, and intestinal microflora and may play a role in insulin resistance and intestinal inflammation. In the present study, we evaluated whether RELMβ could be measured in human plasma and the influence of selected host and behavioral factors on RELMβ levels, including known risk factors for colorectal cancer. Methods: The subjects for this pilot study were derived from healthy controls who participated in a population-based case–control study of colorectal cancer in Metropolitan Detroit. The subjects were 45–80 years of age without history of cancer or colorectal resection. Results: RELMβ was present in human plasma, with levels in the range of 0.08–0.26 ng/mL. Lower RELMβ levels were found in subjects with non-Caucasian race, lower pack-years of smoking, and higher physical activity index scores. Other variables such as dietary intakes, gender, obesity, use of non-steroidal anti-inflammatory agents and history of polyps were not associated with RELMβ levels. Conclusions: The direct association of RELMβ with smoking and inverse association with physical activity, both of which are risk factors for colon cancer, indicates that RELMβ may be involved in mediating the effects of these two lifestyle factors on risk of colon cancer.     

Dietary Patterns and the Metabolic Syndrome in Obese and Non‐obese Framingham Women**

Objectives: To examine the relationship between habitual dietary patterns and the metabolic syndrome (MetS) in women and to identify foci for preventive nutrition interventions. Research Methods and Procedures: Dietary patterns, nutrient intake, cardiovascular disease (CVD), and MetS risk factors were characterized in 1615 Framingham Offspring‐Spouse Study (FOS) women. Dietary pattern subgroups were compared for MetS prevalence and CVD risk factor status using logistic regression and analysis of covariance. Analyses were performed overall in women and stratified on obesity status; multivariate models controlled for age, apolipoprotein E (APOE) genotypes, and CVD risk factors. Results: Food and nutrient profiles and overall nutritional risk of five non‐overlapping habitual dietary patterns of women were identified including Heart Healthier, Lighter Eating, Wine and Moderate Eating, Higher Fat, and Empty Calories. Rates of hypertension and low high‐density lipoprotein levels were high in non‐obese women, but individual MetS risk factor levels were substantially increased in obese women. Overall MetS risk varied by dietary pattern and obesity status, independently of APOE and CVD risk factors. Compared with obese or non‐obese women and women overall with other dietary patterns, MetS was highest in those with the Empty Calorie pattern (contrast p value: p < 0.05). Discussion: This research shows the independent relationship between habitual dietary patterns and MetS risk in FOS women and the influence of obesity status. High overall MetS risk and the varying prevalence of individual MetS risk factors in female subgroups emphasize the importance of preventive nutrition interventions and suggest potential benefits of targeted behavior change in both obese and non‐obese women by dietary pattern.     

Overweight in Swiss children and associations with children's and parents' characteristics

Objective: The objective was to assess the prevalence of overweight and obesity in children in a canton of Switzerland and the association with various characteristics of the parents and the children. Research Methods and Procedures: A cross‐sectional survey was conducted in all children of the sixth school grade of the canton of Vaud, Switzerland. Weight and height were measured, and selected lifestyle variables were assessed with a self‐administered semiquantitative questionnaire. Information on children's parents was gathered through a mailed structured questionnaire. Overweight and obesity were based on the International Obesity Task Force criteria. Results: Of 6873 eligible children, 5207 (76%) participated (2621 boys, 2586 girls; mean age, 12.3 years; standard deviation, 0.5 year). The prevalence of overweight (including obesity) was 15.0% (95% confidence interval, 13.7% to 16.4%) in boys and 12.4% (11.1% to 13.7%) in girls, and the prevalence of obesity was 1.8% (1.3% to 2.3%) and 1.7% (1.2% to 2.2%), respectively. In both univariate and multivariate analyses, overweight was strongly associated with high television viewing time and selected characteristics of the parents (overweight, low educational level, and foreign nationality). Discussion: The prevalence of pediatric overweight and obesity was lower in this region of Switzerland than in several European countries. The correlates of overweight found in this region suggest areas for potential interventions.     

Effects of dietary thymol‐carvacrol on growth performance,hematological parameters and tissue composition of juvenile rainbow trout,Oncorhynchus mykiss

Growth performance, carcass quality, survival and hematological responses of Oncorhynchus mykiss juveniles (initial weight 8.4 ± 0.1 g) fed diets containing thymol‐carvacrol powder at the levels of 0, 1.0, 2.0, 3.0 g kg^?1 were tested. Thymol‐carvacrol powder originated from Origanum vulgare, a Mediterranean plant, added to diets. Each diet was fed to triplicate groups of fish for 45 days. Fish fed diets containing thymol‐carvacrol had significantly higher final weight and growth than the control group. Food conversion ratio in fish fed diets containing 2.0 and 3.0 g kg^?1 thymol‐carvacrol was statistically better than in other treatments. Survival was not different among all treatments. The number of lymphocytes increased when thymol‐carvacrol was used at higher levels. Furthermore, whole body lipid content was higher in fish fed 1.0 and 2.0 g kg^?1 thymol‐carvacrol than the other groups, but body protein in the group fed 3.0 g kg^?1 was higher than in other groups. Also, body ash in control and 1.0 g kg^?1 was higher than in other groups. Whole body dry matter was not affected by dietary treatments. These results indicated that dietary administration of thymol‐carvacrol can influence some growth, hematological parameters and tissue composition in rainbow trout juveniles.