Decreased Body Fat Mass Research Articles

Functional changes in adipose tissue in a randomised controlled trial of physical activity.

BackgroundA sedentary lifestyle predisposes to cardiometabolic diseases. Lifestyle changes such as increased physical activity improve a range of cardiometabolic risk factors. The objective of this study was to examine whether functional changes in adipose tissue were related to these improvements.MethodsSeventy-three sedentary, overweight (mean BMI 29.9 ± 3.2 kg/m2) and abdominally obese, but otherwise healthy men and women (67.6 ± 0.5 years) from a randomised controlled trial of physical activity on prescription over a 6-month period were included (control n = 43, intervention n = 30). Detailed examinations were carried out at baseline and at follow-up, including fasting blood samples, a comprehensive questionnaire and subcutaneous adipose tissue biopsies for fatty acid composition analysis (n = 73) and quantification of mRNA expression levels of 13 candidate genes (n = 51), including adiponectin, leptin and inflammatory cytokines.ResultsAt follow-up, the intervention group had a greater increase in exercise time (+137 min/week) and a greater decrease in body fat mass (−1.5 kg) compared to the control subjects (changes of 0 min/week and −0.5 kg respectively). Circulating concentrations of adiponectin were unchanged, but those of leptin decreased significantly more in the intervention group (−1.8 vs −1.1 ng/mL for intervention vs control, P < 0.05). The w6-polyunsaturated fatty acid content, in particular linoleic acid (18:2w6), of adipose tissue increased significantly more in the intervention group, but the magnitude of the change was small (+0.17 vs +0.02 percentage points for intervention vs control, P < 0.05). Surprisingly leptin mRNA levels in adipose tissue increased in the intervention group (+107% intervention vs −20% control, P < 0.05), but changes in expression of the remaining genes did not differ between the groups.ConclusionsAfter a 6-month period of increased physical activity in overweight elderly individuals, circulating leptin concentrations decreased despite increased levels of leptin mRNA in adipose tissue. Otherwise, only minor changes occurred in adipose tissue, although several improvements in metabolic parameters accompanied the modest increase in physical activity.

Seasonal variations of body mass, thermogenesis and digestive tract morphology in Apodemus chevrieri in Hengduan mountain region

Seasonal changes in an animal’s morphology, physiology, and behavior are considered to be an adaptive strategy for survival and reproductive success. We hypothesize thatApodemus chevrieriwill change their thermogenesis seasonally and serum leptin will change with body mass or body fat mass. Seasonal variations in body mass (BM), basal metabolic rate (BMR), nonshivering thermogenesis (NST), digestive tract morphology, serum leptin and uncoupling protein 1 (UCP1) were measured in wild-trappedA. chevrieriin Hengduan mountain region. The results showed that the body weight ofA. chevrieriwas lowest in winter and highest in summer. Decreased BM in the winter was accompanied by increased energy intake and enhanced NST and UCP1 as well as by decreased body fat mass, adjusted digestive tract morphology and reduced levels of circulating leptin. Further, serum leptin were positively correlated with body weight and body fat mass, and negatively correlated with energy intake and UCP1 contents. These data suggest that wildA. chevrierido not depend on a decrease in BM, but instead increase their thermogenic capacity to cope with cold stress. Leptin may be involved in the seasonal regulation in energy balance and thermogenesis in fieldA. chevrieri.

P2-427 Body mass analysis in primary school age children in Latvia

IntroductionThe prevalence of excessive and insufficient body mass in children is increasing worldwide according to epidemiologic researches. There is a risk of health disorder with the fluctuation of body mass.AimTo...

Differential effect of weight loss with low-fat diet or high-fat diet restriction on inflammation in the liver and adipose tissue of mice with diet-induced obesity

ObjectiveWe studied the effects of weight loss induced by either a low-fat normal diet (ND) or restriction of high-fat diet (HFD) on hepatic steatosis, inflammation in the liver and adipose tissue (AT), and blood monocytes of obese mice. MethodsIn mice with HFD-induced obesity, weight loss was achieved by switching from HFD to ND and maintaining on ND ad libitum or by restricting HFD intake to match body weight of mice with ND-induced weight loss. After diet interventions for 4 weeks, hepatic steatosis, hepatic and AT inflammation, and blood CD11c+ monocytes were examined. ResultsAt 4 weeks after switching diets, body weight was reduced by 23% from baseline. To achieve the same reduced body weight required restricting calorie intake from HFD. Weight loss with either ND or HFD restriction decreased body fat mass and ameliorated liver steatosis; both effects were greater with ND-induced weight loss than HFD restriction-induced weight loss. Weight loss with ND but not HFD restriction normalized blood CD11c+ monocytes and attenuated hepatic inflammation assessed by chemokine and CD11c expression. In contrast, weight loss with HFD restriction significantly reduced chemokine levels and CD11c+ cells in AT compared to obese controls, and tended to reduce AT chemokines and CD11c+ cells more than ND-induced weight loss. ConclusionIn mice with diet-induced obesity, weight loss with ND was superior in alleviating hepatic inflammation and steatosis, whereas weight loss with HFD calorie restriction provided greater amelioration of AT inflammation.

Salzburg Skiing for the Elderly Study: changes in cardiovascular risk factors through skiing in the elderly

Numerous studies have shown that treatment of the modifiable cardiovascular risk factors (CVRF) results in a decreased risk to suffer from stroke or myocardial infarction. Despite the fact that exercise training is a potent treatment choice for CVRF, this is the first randomized study to assess the effects of alpine skiing on CVRF in elderly skiers. Subjects (n=42) were randomized into an intervention group (IG; n=22; 12 males/10 females; age: 66.6 ± 2.1 years) completing 12 weeks of guided skiing or a control group (CG; n=20; 10 males/10 females; age: 67.3 ± 4.4 years). CVRF were assessed before and after the intervention period. No cardiovascular event occurred within a total of 795.1 h of skiing. A significant increase in exercise capacity in IG (ΔVO(2 max) : +2.0 mL/kg/min, P=0.005) but not in CG (ΔVO(2 max) : -0.1 mL/kg/min, P=0.858; IG vs CG: P=0.008) as well as a decrease in body fat mass [IG: -2.3%, P<0.0001; CG: ± 0.0%, P=0.866; IG vs CG: P<0.0001] was achieved. Blood pressure, blood lipids, heart rate and everyday physical activity remained essentially unchanged. Alpine skiing in the elderly is safe with respect to cardiovascular events, and improves some, but not all CVRF.

Compliance with Mediterranean Diet Quality Index (KIDMED) and nutrition knowledge levels in adolescents. A case study from Turkey

Adopting an eating pattern complying with the Mediterranean diet not only decreases body fat mass and obesity risk, but also reduces development of various health problems. This study investigated the nutritional awareness and diet quality Mediterranean Diet Quality Index (KIDMED) of Turkish adolescents. The study was conducted with 890 voluntary participants (464 boys and 426 girls) aged 10–14 years. A questionnaire form was used to learn demographic characteristics of the participants. Participants’ nutritional awareness was determined through a 20-item knowledge form and their nutritional habits through a 16-item Mediterranean Diet Quality Index (KIDMED). The average nutritional knowledge score was X = 82.22 ± 0.42. Results indicated that 17.9% of the participants had a low quality diet (≤3 points), 59.2% had a mid-quality/needs-improvement diet (4–7 points) and 22.9% had an optimal quality diet (≥8 points). The study results showed that the subjects’ diet quality was low and that their nutrition knowledge levels were related to their nutritional habits.

Pomegranate seed oil, a rich source of punicic acid, prevents diet-induced obesity and insulin resistance in mice

BackgroundPomegranate seed oil has been shown to protect against diet induced obesity and insulin resistance. ObjectiveTo characterize the metabolic effects of punicic acid on high fat diet induced obesity and insulin resistance. DesignHigh-fat diet or high-fat diet with 1% Pomegranate seed oil (PUA) was fed for 12weeks to induce obesity and insulin resistance. We assessed body weight and composition (pSABRE DEXA-scan), energy expenditure (Columbus Instruments) and insulin sensitivity at the end of the 12weeks. ResultsPSO intake resulted in a lower body weight, 30.5±2.9 vs 33.8±3.2g PSO vs HFD respectively, p=0.02, without affecting food intake or energy expenditure. The lower body weight was fully explained by a decreased body fat mass, 3.3±2.3 vs 6.7±2.7g for PSO and HFD fed mice, respectively, p=0.02. Insulin clamps showed that PSO did not affect liver insulin sensitivity but clearly improved peripheral insulin sensitivity, 164±52% vs 92±24% for PSO and HFD fed mice respectively, p=0.01. ConclusionsWe conclude that dietary PSO ameliorates high-fat diet induced obesity and insulin resistance in mice, independent of changes in food intake or energy expenditure.

Maximal fat oxidation at the different exercise intensity in obese and normal weight men in the morning and evening

Mohebbi H, Azizi M. Maximal fat oxidation at the different exercise intensity in obese and normal weight men in the morning and evening. J. Hum. Sport Exerc. Vol. 6, No. 1, pp. 49-58, 2011. Introduction: Circadian rhythms regulate some metabolic and hormonal variables that affect fat oxidation rates. Thus, the purpose of this study was to investigate Maximal fat oxidation (MFO) at a different exercise intensity in obese and normal weight men in the morning and evening. Methods: MFO was measured in 12 normal weight (BMI 20-25 kg/m 2 ; VO2max 45.7±3.44 ml/min/kg) and 10 obese (BMI >30 kg/m 2 ; VO2max 37.2±3.6 ml/min/kg) men during incremental running exercise test with 3 min stages on the treadmill by indirect calorimetry method. Student’s t-test and one-way ANOVA with repeated measures were used to analysis variables. Results: We found that fat oxidation rates and energy expenditure in both groups in the evening were higher than morning; there were no significant differences in MFO between obese and normal groups. Furthermore, the fat oxidation rate in low intensity exercise (<60% VO2max) was similar in obese and normal weight groups, but in high exercise intensities, in normal weight men were significantly higher than obese men. Conclusion: Our results suggest that independent of exercise intensity and body fat mass, exercising in the evening is more effective on fat oxidation and decrease body fat mass; therefore, it is

Chronic Effect of Light Resistance Exercise after Ingestion of a High-Protein Snack on Increase of Skeletal Muscle Mass and Strength in Young Adults

We have previously reported on the possibility that light resistance exercise performed with a high plasma amino acid concentration resulting from the ingestion of a high-protein snack (HPS; 15 g protein, 18 g sugar) 3 h after a basal meal promotes the utilization of amino acids in peripheral tissues such as muscle in both rats and humans. In the present study, we further examined the effectiveness of a daily routine involving ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise (dumbbell exercise) in increasing the mass and strength of human muscle. Ten young adult males were subject to the following 3 conditions for 5 wk each, with sufficient recovery period between each condition: (1) Snack-Exercise (SE), (2) Snack-Sedentary (SS), and (3) No snack-Exercise (NE). The SE group showed a significant increase in lean body mass and total cross-sectional area (CSA) of the right forearm muscles along with a significant decrease in body fat mass. The SS group showed no change in body composition. Furthermore, the SE group showed significant increase in grip strength and isometric knee extensor muscle strength, while the SS group showed no increase in muscle strength. The NE group showed significant increase in grip strength. In conclusion, daily routine ingestion of HPS 3 h after a basal meal and subsequent light resistance exercise is effective in increasing the mass and strength of human muscle.

Peroxisome proliferator-activated receptor β/δ: a master regulator of metabolic pathways in skeletal muscle.

Skeletal muscle is considered to be a major site of energy expenditure and thus is important in regulating events affecting metabolic disorders. Over the years, both in vitro and in vivo approaches have established the role of peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) in fatty acid metabolism and energy expenditure in skeletal muscles. Pharmacological activation of PPARβ/δ by specific ligands regulates the expression of genes involved in lipid use, triglyceride hydrolysis, fatty acid oxidation, energy expenditure, and lipid efflux in muscles, in turn resulting in decreased body fat mass and enhanced insulin sensitivity. Both the lipid-lowering and the anti-diabetic effects exerted by the induction of PPARβ/δ result in the amelioration of symptoms of metabolic disorders. This review summarizes the action of PPARβ/δ activation in energy metabolism in skeletal muscles and also highlights the unexplored pathways in which it might have potential effects in the context of muscular disorders. Numerous preclinical studies have identified PPARβ/δ as a probable potential target for therapeutic interventions. Although PPARβ/δ agonists have not yet reached the market, several are presently being investigated in clinical trials.

Effect of Oligomerised Polyphenol Supplementation on Lipid Metabolism during Aerobic Exercise in Young Subjects

PURPOSE: Foods rich in polyphenols, especially flavonoids, have been shown to improve endothelial function, insulin sensitivity, and decrease body fat mass, although mechanisms involved are mostly unknown. Therefore, the purpose of the current study was to determine the short-term (14days) supplementation of oligomerized polyphenol on lipid metabolism during submaximal aerobic exercise in healthy young subjects. METHODS: Eight healthy young males were studied in a double blind manner and given either oligomerized polyphenol (100mg/day) or placebo for 14 days. Before and after the supplementation period, each subject performed an aerobic exercise (30min bicycle ergometer at 50%VO2peak). Blood samples were taken to assess glycerol, free fatty acid, growth hormone, and cortisol to assess the lipid metabolism during and following the bout of exercise. RESULTS: In response to a 30min aerobic exercise, growth hormone and lactate increased significantly during exercise in both groups, while no significant group differences were observed. Free fatty acid tended to increase 15min post-exercise in both groups with no significant group differences. Plasma concentrations of glycerol increased significantly in CON group during exercise, and glycerol concentration of OLG group were even higher as compared to CON at 15min and 30min post-exercise (6.5±0.62 and 15.2±3.64 mg/dl at 15min-post, 5.1±0.83 and 11.8±2.36 mg/dl at 30min-post for CON and OLG, respectively; P<0.05). CONCLUSIONS: In conclusion, supplementation of origomerized polyphenol for 14 days increased glycerol concentration following a bout of moderate-intensity aerobic exercise, indicating an increased lipolysis.FIGURE

Influencia pronóstica del índice de masa corporal y su relación con la composición corporal en pacientes con insuficiencia cardiaca

Introduction and objectives Observational data suggest a protective effect of obesity in heart failure but the relationship with body composition has not yet been studied. The objective of our study is to examine the prognosis influence of body mass index and body composition. Methods Baseline body mass index, tricipital skin-fold and brachial muscle circumference were recorded in 208 patients admitted due to heart failure. They were divided into four groups according to BMI: low weight (<20.5), normal weight (20.5 to <25.5), overweight (25.5 to <30), and obese (≥30) and in three groups according to tricipital skin fold and brachial muscle circumference (p<5, p 5–94, p≥95). Results There was a difference in the mortality rate at 1 year ( P<0.001) between low-weight patients and the other groups, with no differences between them: 80% for low-weight patients, 32.6% for normal-weight patients, 21.6% for overweight patients, and 17.9% for obese patients. The same was observed between p<5 tricipital skin fold patients and the other groups (64.3% p<5, 19.1% p 5–95 and 25.4% p≥95, P=0.002). No differences were observed between brachial muscle circumference groups. After adjusting for different prognosis variables, body mass index and tricipital skin fold remained as independent predictor of reduced mortality at 1 year in multivariate analysis (Hazard ratio=0.93 [0.87–0.98]). Conclusions In our study, body mass index is an independent risk factor in heart failure due to the group of low weight patients. The poor survival of this group is associated with a decrease in body composition characterised by a decreased body fat mass.

Possible regulatory factors for intra-abdominal fat mass in a rat model of Parkinson's disease

Objective Patients with Parkinson's disease (PD) lose body weight primarily due to decreased body fat mass. The purpose of this study was to elucidate possible factors related to reduction in the intra-abdominal fat mass of 6-hydroxydopamine (6-OHDA)-treated rats, which are frequently used as an animal model for PD. Methods Sham-operated (NPD: n = 4) and unilaterally 6-OHDA-injected (PD: n = 4) 14-wk-old male Sprague-Dawley rats were fed a relatively high-fat diet for 2 wk, during which food intake and body weight were measured. After the 2-wk feeding period, intra-abdominal fat was dissected out and weighed. Carbohydrate and fat absorption-related gene expressions in the jejunum and serum insulin and glucose concentrations were analyzed. Results Although final body weights did not differ, total intra-abdominal fat weight, expressed relative to body weight, was significantly lower in the PD group than in the NPD group ( P < 0.05). There were no significant differences between the two groups in the mRNA expression of carbohydrate and fat digestion/absorption-related genes in the jejunum, or in fat absorption efficacy assessed by fecal fat excretion. However, PD rats showed significantly lower serum insulin and higher glucose concentrations than NPD rats ( P < 0.05). Conclusion PD model rats displayed loss of intra-abdominal fat, similar to the progressive loss of fat in PD patients. Our results provide preliminary evidence that reduced lipogenesis due to lower insulin levels, rather than impaired digestion/absorption, might have been involved in this decrease in intra-abdominal fat mass.

Acipimox, an Inhibitor of Lipolysis, Attenuates Atherogenesis in LDLR-Null Mice Treated With HIV Protease Inhibitor Ritonavir

The advent of HIV protease inhibitors has greatly extended the life span of AIDS patients. With an aging HIV(+) population, the cardiometabolic side effects of these drugs are becoming increasingly important clinical concerns. The purpose of this study was to test the hypothesis that inhibition of adipose lipolysis will retard atherogenic lesion development induced by the antiviral protease inhibitors. LDLR-null mice receiving ritonavir were compared with those receiving ritonavir plus lipolysis inhibitor acipimox or vehicle alone to determine how acipimox would affect ritonavir-induced atherogenesis. Intermittent high-fat high-cholesterol diet was used to facilitate optimal atheromatous lesion development. Drug effects were assessed as changes in aortic lesion score, plasma lipid and lipoprotein profile, body fat mass, and insulin-induced suppression of plasma fatty acid concentrations. Ritonavir increased aortic lesions, in association with decreased body fat mass, impaired antilipolysis action of insulin, and increased proatherogenic plasma lipoproteins. All these adverse effects were attenuated by cotreatment with acipimox. Our results provide the first direct evidence that supports the hypothesis that dysregulation of adipose lipolysis is an important contributor to the proatherogenic role of selected HIV protease inhibitors.

Impact of diet and exercise intervention on breast ductal fluid among overweight postmenopausal women

Obesity and adulthood weight gain, operating through production of estrone in adipose tissue, inflammation, and obesity-related growth factors, increase breast cancer risk after menopause. Many studies have determined the systemic effects of excess adipose tissue on plasma and serum-based biomarkers, but few studies have determined the localized impact on biomarkers contained in breast ductal fluid. We are currently conducting a pilot 12-week diet and exercise weight-loss intervention among overweight postmenopausal women to evaluate changes in ductal fluid as a result of the intervention. To date, five women completed the study. We successfully obtained breast ductal fluid both before and after the intervention from four of the five women. Fluid was transferred into tubes and frozen in a -80° freezer. We are currently conducting assay measurements of hormones and biomarkers contained in ductal fluid. We observed changes in body composition and exercise parameters as a function of the intervention. Specifically, a 12% decrease in BMI (body-mass index), a 14% decrease in body fat mass, a 28% increase in aerobic fitness and 28% increase in muscle-strength occurred compared to baseline intervention measurements, among the women who completed the study. Our plans are to enroll five additional women, finish analyzing the ductal fluid biomarkers, and apply for a larger grant to expand the study.

Relationship between diet-induced changes in body fat and appetite sensations in women

To quantify the impact of weight/fat loss on appetite sensations, 54 overweight women followed a caloric restriction program (−2900kJ/day). Their body composition and appetite sensations were assessed. Visual analogue scales (VAS) were used to measure desire to eat, hunger, fullness and prospective food consumption. The results showed that there is a significant association between the decrease in body fat mass and the change in appetite sensations, predicting a 5.8-mm increase in desire to eat and a 3.6-mm decrease in fullness per kg fat loss. This quantified relationship could serve as a reference point to evaluate the satiating efficiency of functional foods when they are combined with a weight-reducing program.

Weight loss, body fat mass, and leptin in Parkinson's disease

Weight loss is a common problem in Parkinson's disease (PD), but the causative mechanisms behind this weight loss are unclear. We compared 26 PD patients with sex and age matched healthy controls. Examinations were repeated at baseline, after one and after two years. Body fat mass was measured by Dual X-ray Absorptiometry (DXA). Seventy three per cent of the PD patients lost body weight. Loss of body fat mass constituted a considerable part of the loss of body weight. In the patients who lost weight, serum leptin levels were lower than in those who did not lose weight. The relationship between low body fat mass and low leptin levels seems to be relevant, at least for female PD patients. It is reasonable to believe that low leptin levels in these patients could be secondary to the decreased body fat mass.

Dietary conjugated linoleic acid increases PPARγ gene expression in adipose tissue of obese rat, and improves insulin resistance

Conjugated linoleic acid (CLA) is a class of positional, geometric, conjugated dienoic isomers of linoleic acid. Dietary CLA supplementation has resulted in a dramatic decrease in body fat mass in mice. However, some but not all studies in mice and humans have found that CLA promoted insulin resistance, and there were conflicting reports on the effects of CLA on peroxisomal proliferator-activated receptor-γ (PPARγ) activation and expression. The objective of present study was to investigate the effect of CLA on insulin resistance and its molecular mechanisms. Fifty male Wistar rats were randomly designed to the control, high-fat and high-fat with CLA (0.75, 1.50, and 3.00 g in per 100 g diet) groups. The effect of CLA on insulin sensitivity and the mechanism of resisting diabetes by CLA were investigated by RT-PCR assay. The results showed that supplementation with CLA significantly reduced body weight gain and white fat pad weight in the rats, the levels of plasma free fatty acids (FFA), triglycerides (TGs), cholesterin (TC), leptin, insulin and blood glucose concentration in the obese rats of CLA group were also decreased compared to the rats in the high-fat group. Dietary CLA increased the mRNA expression of PPARγ, fatty acid binding proteins (aP2), fatty acid transporter protein (FATP), acyl-CoA synthetase (ACS) and adiponectin in the adipose tissues of obese rats. The results suggest that CLA may ameliorate insulin resistance by activating PPARγ, and increasing the expression of PPARγ target genes such as ap2, FATP, FAT, and adiponectin in the white adipose tissue.

Chronic effect of CLA isomers on bone mineral density, fat and lean mass in C57BL/6 female mice

Conjugated linoleic acids (CLA) are a class of positional, geometric, conjugated dienoic isomers of linoleic acid (LA). Dietary CLA supplementation results in a dramatic decrease in body fat mass and increase in lean mass as well as protects against bone loss both in mice and humans. However, little information is known of the long term effect of CLA isomers in animals as well as in humans. In order to investigate the isomer specific effects of CLA on fat and lean mass, the purified c9,t11‐CLA, (0.5%), t10,c12‐CLA (0.5%) and CLA‐mix (0.25%, c9,t11‐CLA + 0.25% t10,c12‐CLA) were fed along with 10% corn oil (CO) to 6 months old C57BL/6 female mice (n=8–10) for 6 months. All of the dietary interventions of CLA groups were compared with CO fed mice as a control group. After 6 months, mice were scanned using DEXA to measure the bone mineral density (BMD), lean and fat mass. The results revealed that, the body weights were significantly decreased in both t10,c12‐CLA, CLA‐mix groups compared to c9,t11‐CLA and 10% corn oil. Further, t10,c12‐CLA and CLA‐mix groups significantly decreased the total and abdominal fat mass compared to c9,t12‐CLA and CO group. In addition, both CLA‐mix and t10,c12‐CLA significantly increased the lean mass and also BMD in lumbar spine and distal femoral metaphysis compared to corn oil. The overall % fat of the body were decreased significantly in t10,c12‐CLA and CLA‐mix compared to c9,t11‐CLA and CO group. In conclusion, the specific effect of t10,c12‐CLA induces both significant fat mass reduction, maintains higher lean and bone mass compared to c9,t12‐CLA and CO.Research support: NIH R21 AG027562

Conjugated linoleic acid (CLA) and obesity

The term conjugated linoleic acid (CLA) refers to several positional and geometric conjugated dienoic isomers of linoleic acid (LA), of which the trans-10,cis-12 isomer has been reported to reduce adiposity and increase lean mass in mice and other animals when included at <or=1% of the diet. However, most dietary CLA in humans is obtained from dairy products, accounting for the cis-9,trans-11 CLA isomer, also known as rumenic acid, for more than 90% of the total CLA intake. Commercial CLA preparations industrially produced, containing trans-10,cis-12 and cis-9,trans-11 CLA isomers in diverse proportions, are attracting consumers' interest because of the purported body fat-lowering effects of CLA, coupled to the perception of a 'natural' compound devoid of harmful effects. Nevertheless, despite numerous studies on CLA effects on body composition for nearly a decade, the mechanisms by which CLA isomers elicit their effects remain largely unknown. The purpose of this paper is to provide an updated review of the studies performed on animals and humans, as well as to describe the potential mechanisms involved in CLA effects on body weight and composition and metabolism. Literature review. Experiments in humans have not been able to show a significant effect on body weight, body composition or weight regain related to either of the CLA isomers. In fact, some studies suggest a tendency towards a decrease in body fat mass and an increase in body lean mass, while some others raise concern about the possibility of deleterious effects of trans-10,cis-12 CLA on lipid profile, glucose metabolism and insulin sensitivity. Evidence regarding effectiveness of CLA in humans is not concluding.