Fat In Obese Subjects Research Articles

Increased weight loading reduces body weight and body fat in obese subjects – A proof of concept randomized clinical trial

Increased weight loading reduces body weight and body fat in obese subjects – A proof of concept randomized clinical trial

The Gravitostat theory: Body fat is lost but is fat-free mass preserved?

The Gravitostat theory: Body fat is lost but is fat-free mass preserved?

Increased weight loading reduces body weight and body fat in obese subjects – A proof of concept randomized clinical trial

BackgroundRecently we provided evidence for a leptin-independent homeostatic regulation, the gravitostat, of body weight in rodents. The aim of the present translational proof of concept study was to test the gravitostat hypothesis in humans. MethodsWe conducted a randomized controlled single center trial (ClinicalTrial.gov number, NCT03672903), to evaluate the efficacy of artificially increased weight loading on body weight in subjects with mild obesity (BMI 30–35 kg/m2). Subjects were either treated with a heavy (=high load; 11% of body weight) or light (=low load; 1% of body weight) weight vest for eight hours per day for three weeks. The primary outcome was change in body weight. Secondary outcomes included change in body fat mass and fat-free mass as measured using bioelectrical impedance analysis. FindingsIn total 72 participants underwent randomization and 69 (36 high load and 33 low load) completed the study for the primary outcome. High load treatment resulted in a more pronounced relative body weight loss compared to low load treatment (mean difference -1.37%, 95% confidence interval (CI), -1.96 to -0.79; p = 1.5 × 10−5). High load treatment reduced fat mass (-4.04%, 95% CI, -6,53 to -1.55; p = 1.9 × 10−3) but not fat free mass (0.43%, 95% CI, -1.47 to 2.34; p = 0.65) compared to low load treatment. InterpretationIncreased weight loading reduces body weight and fat mass in obese subjects in a similar way as previously shown in obese rodents. These findings demonstrate that there is weight loading dependent homeostatic regulation of body weight, the gravitostat, also in humans. FundingFunded by Jane and Dan Olsson (JADO) Foundation, the Torsten Söderberg Foundation, The Knut and Alice Wallenberg's Foundation and the Novo Nordisk Foundation.

Emulsifying dietary fat modulates postprandial endotoxemia associated with chylomicronemia in obese men: a pilot randomized crossover study

BackgroundPostprandial hyperlipemia is recognized as a major cardio-metabolic risk factor, recently linked to the co-absorption of pro-inflammatory lipopolysaccharides with dietary lipids. This causes endotoxemia that is involved in the pathophysiology of obesity and insulin resistance, but to date the impact of food formulation is unknown. We tested a novel concept that endotoxin absorption can be modulated by fat emulsified structure in the meal, and potentially differently in obese vs. lean men.MethodsIn a randomized controlled crossover study, eight normal-weight and eight obese age-matched healthy men ingested two isocaloric, isolipidic breakfasts of identical composition including 40 g of milk fat that was emulsified or unemulsified. Plasma- and chylomicron-endotoxemia and chylomicron-triglycerides were measured during 8 h after breakfast ingestion.ResultsAfter emulsion consumption, parallel to an enhanced chylomicronemia, obese subjects presented an early and sharp increase in chylomicron-endotoxemia at 60 min (Ptime = 0.02), which was higher than (i) after spread fat in obese subjects (P < 0.05) and (ii) after both spread and emulsified fat in normal-weight subjects (P < 0.05). However in obese subjects, the iAUC of plasma endotoxemia over 8 h was lower after emulsion than after spread fat (P < 0.05) whereas in NW subjects such reduction of plasma LPS-iAUC was not observed (P = 0.67).ConclusionThis study provides initial evidence that optimizing fat structure in the meal can be part of a dietary strategy to lower the metabolic impact of postprandial endotoxemia in obese men.Trial registrationRegistered at ClinicalTrials.gov #NCT01249378 on July 13, 2010.

Abstract 413: CD34+CD31+ Endothelial Cells From Human Obese Subcutaneous but Not Omental Fat Show Adipogenic Potential

In obesity, excess lipid storage and reduced adipogenesis causes adipocytes to undergo hypertrophy leading to inflammation and insulin resistance. Increasing adipogenic potential may reduce lipid overload and ectopic lipid accumulation. In mice, the vascular niche is a source of adipocyte progenitors and a subset of endothelial cells (ECs) can trans-differentiate to functional adipocytes. It is unknown if a similar process occurs in humans. Our hypothesis is that pro-inflammatory cytokines contribute to de-differentiation and support induction of a pro-adipogenic program in a subset of CD31+CD34+ EC in human fat. The aim of this study is to determine if CD34+ CD31+ ECs isolated from human obese fat can be trans-differentiated to adipocytes and if this process is depot-specific. CD31+CD34+ ECs isolated from subcutaneous (SC) or omental (OM) fat of obese subjects undergoing bariatric surgery (BAMVECs) were treated with 2.5ng/mL of IFNγ and TNFα for 24 hrs then cultured in adipocyte induction medium (AIM), containing insulin and rosiglitazone, for up to 21 days. Cells without cytokine treatment and/or grown in media without induction were used as controls. Lipid accumulation was quantified with AdipoRed. OM BAMVECs showed no lipid accumulation in AIM alone (RFU ratio 1.1 vs control) nor with prior cytokine treatment (RFU ratio 1.6 vs control). However, SC BAMVECs showed lipid accumulation in AIM alone (RFU ratio 2.7 vs control) and with a trend to increased lipid accumulation with prior cytokine treatment (RFU ratio 4.1 vs control). By RT-PCR, SC BAMVECs pre-treated with cytokines had a 6-fold increase in pre-adipocyte commitment marker zfp423 and a 106,000 increase in adiponectin vs controls. The increases vs controls in AIM alone were 2.6x for zfp423 and 21,700x for adiponectin. We conclude that SC but not OM BAMVECs can trans-differentiate to adipocytes as shown by lipid droplet accumulation and increased expression of adipocyte markers. Cytokine stimulation trended to increase EC plasticity. This indicates that CD34+ CD31+ ECs within the SC depot, when stimulated, may play a protective role by supplementing the adipocyte pools thus increasing growth and function of adipose tissue and potentially reducing ectopic fat storage.

The effect of concurrent training order on hormonal responses and body composition in obese men

Summary Objectives The purpose of this study was to investigate the effects of intrasession sequencing of concurrent resistance and endurance training on the serum leptin, testosterone, cortisol responses and body composition in obese men. Patients and methods Thirty obese young men students (age = 23.2 ± 1.4 year, BMI = 31.8 ± 1.6 kg/m 2 ) were randomly divided into three groups: concurrent resistance-endurance (CRE, n = 10) group, concurrent endurance-resistance (CER, n = 10) group and control (C, n = 10) group (no training program). Concurrent training groups (CER and CRE) were conducted three times a week on alternate days for 8 weeks, which consisted of running with 70–75% of maximal heart rate (HRmax) for 10 minutes which gradually increased to 80% HRmax for 21.5 minutes and the resistance training consisted of 3 sets of 8 repetitions at 80% of 1 repetition maximum (1RM) in 5 resistance exercises (leg extensions, lying leg curl, triceps pushdown, bench press and lateral pull down). Five minutes recovery duration was set between resistance and endurance phases. To measure hormonal and body composition changes, blood sampling was conducted 48 hours before the start of the course and again 48 hours after the last training session. Results Results using ANOVA with repeated measurement showed that there were no significant differences within groups and between groups for testosterone hormone. Serum levels of cortisol in both experimental groups were significantly increases after 8 weeks of concurrent training. While, there were significantly decreases in leptin and testosterone/cortisol ratio after 8 weeks training intervention in both experimental groups. Also, in the CRE and CER groups, a significant decrease observed in the body mass, body fat and body mass index. In addition, the control group did not change significantly in the posttest in none of the variables. Comparison between groups showed similarly that the CRE group compared with the control group, have a significant positive changes in all hormonal and body composition variables, however, no significant difference was observed between the CRE and CER groups. Conclusion It can be concluded that concurrent resistance and endurance training aimed at weight loss by reducing body fat in obese subjects can be a good strategy, although the both CRE and CER order were effective in positive transformation of serum leptin, testosterone, cortisol concentration and body composition. However, concurrent resistance-endurance (CRE) training may have better efficacy.

Growth hormone signaling in muscle and adipose tissue of obese human subjects: associations with measures of body composition and interaction with resveratrol treatment.

Growth hormone (GH) secretion is reduced in obesity, despite normal serum insulin-like growth factor I (IGF-1) levels, but the association between obesity and the GH signaling is unknown. Furthermore, SIRT1, an nicotinamide adenine dinucleotide-dependent protein deacetylase, reduces hepatic IGF-1 production in mice via blunting of GH-induced STAT5 signaling. To study GH signaling in muscle and fat in obese subjects and the interaction with concomitant administration of the putative SIRT1 activator resveratrol, and to assess the effects of inhibiting or knocking down SIRT1 on GH regulated genes in vitro. Twenty-four obese males were examined in a randomized, double blinded, parallel-group study with resveratrol or placebo treatment for 5 weeks followed by a GH bolus. Muscle and fat biopsies were collected before and after GH. Body composition was assessed by DEXA and MRI. (1) Effect of body composition and age on GH-stimulated STAT5b phosphorylation and IGF-1, SOCS2, and CISH mRNA in muscle and fat. (2) The impact of resveratrol treatment on GH activity. (3) Impact of inhibiting or knocking down SIRT1 on effects of GH in vitro. Significant GH-induced STAT5b phosphorylation in muscle and fat in obese subjects was recorded together with increased CISH and SOCS2 mRNA. GH-induced STAT5b phosphorylation in muscle correlated positively with age [r = 0.53, p < 0.01], but not with body composition. Resveratrol administration had no impact on body composition, serum IGF-1, or GH signaling in vivo, and SIRT1 knock down or inhibition did not affect GH signaling in vitro. (1) GH induced STAT5b phosphorylation is detectable in muscle and fat in adult males with simple obesity, but is not determined by body composition. (2) Resveratrol supplementation does not impact circulating IGF-1 levels or GH signaling in human muscle and fat. (3) Our data speak against a major impact of SIRT1on GH action in human subjects.

Relationship between the percentage of body fat and surrogate indices of fatness in male and female Polish active and sedentary students.

BackgroundLimited data have indicated that body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and waist to height ratio (WHtR) of athletes and young adults provide misleading results concerning body fat content. This study was aimed at the evaluation of the relationship between different surrogate indices of fatness (BMI, WC, WHR, WHtR and body adiposity index (BAI)) with the percentage of body fat in Polish students with respect to their sex and physical activity.MethodsA total of 272 students volunteered to participate in the study. Of these students, 177 physical education students (90 males and 87 females) were accepted as active (physical activity of 7 to 9 hours/week); and 95 students of other specializations (49 males and 46 females) were accepted as sedentary (physical activity of 1.5 hours/week). Weight, height, waist and hip circumferences were measured, and BMI, WHR, WHtR and BAI were calculated. Body fat percentage was assessed using four skinfold measurements.ResultsClassification of fatness according to the BMI and the percentage of body fat have indicated that BMI overestimates fatness in lean subjects (active men and women, sedentary men), but underestimates body fat in obese subjects (sedentary women). In all groups, BMI, WHR, WHtR and BAI were significantly correlated with the percentage of body fat (with the exception of WHR and hip circumference in active and sedentary women, respectively). However, coefficients of determination not exceeding 50% and Lin’s concordance correlation coefficients lower than 0.9 indicated no relationship between measured and calculated body fat.ConclusionThe findings in the present study support the concept that irrespective of physical activity and sex none of the calculated indices of fatness are useful in the determination of body fat in young adults. Thus, it seems that easily calculated indices may contribute to distorted body image and unhealthy dietary habits observed in many young adults in Western countries, but also in female athletes.

Effect of licorice flavonoid oil on visceral fat in obese subjects in the United States

Abdominal obesity, or accumulation of visceral fat, is mainly associated with the onset of metabolic syndrome. Licorice flavonoid oil (LFO) consisting of licorice hydrophobic polyphenols in mediumchain triglycerides (MCT) is a new functional food ingredient effective in preventing metabolic syndrome. We have demonstrated significant effects of LFO on reduction of total body fat and visceral fat together with body weight in overweight Japanese subjects. Obesity is a more serious problem in Western countries such as Europe and the United States compared to Japan. We hypothesized that LFO could also work for abdominally obese people in Western countries. We therefore tested the effects of 300 mg LFO concentrate solution taken once daily with evening meals for up to 12 weeks in obese adult male and female subjects in the United States. Results showed that visceral fat, as measured by an abdominal CT scan, waist circumference measurements and waist-to-hip ratio significantly decreased in subjects in the LFO group compared to the placebo group at Week 12. The side-effect profile of LFO was indistinguishable from placebo. Moreover, no adverse trends or toxicologically meaningful differences in haematology and chemistry test results, vital signs or physical examinations were observed that were attributable to LFO. These results indicate that LFO is a safe food ingredient for preventing metabolic syndrome not only in Japan but also in Western countries such as Europe and the United States.

Significant features of basal and maximal energy expenditure parameters in obese adults

To compare body composition, resting metabolic rate, and maximal aerobic capacity parameters in obese adults and healthy controls, as well as to investigate the associations among these parameters. Materials and methods: A total of 120 participants, 60 obese participants (30 male, 30 female) with body mass indexes (BMIs) over 30 kg/m^2 and 60 healthy controls (30 male, 30 female) with BMIs of 18-25 kg/m^2, were included in the study. BMI was calculated as body weight divided by the square of the height (kg/m^2). Body fat percentage, total body fat, and lean body mass were established with bioelectric impedance analysis. Resting metabolic rates (RMRs) were determined with indirect calorimeter. Maximal aerobic capacity was estimated with the Astrand exercise protocol. Results: RMRs (kcal/day) were significantly higher in male and female obese individuals than in the controls. VO2max (L/min) levels were not significantly different between obese and control individuals of either sex. However, RMR per kilogram of body weight and VO2max expressed in milliliters per kilogram of body weight were significantly lower in male and female obese adults compared to the controls. BMI, body fat percentage, and total body fat were positively correlated with RMR (kcal/day), but negatively correlated with RMR [(kcal/day)/kg] and VO_2max (mL/kg/min) in both sexes. Conclusion: We suggest that resting and maximal energy expenditure per kilogram of body weight are impaired in obese adults. Both low resting metabolic rate and weak maximal aerobic capacity are related to excess body fat in obese subjects.

Type I iodothyronine 5′-deiodinase mRNA and activity is increased in adipose tissue of obese subjects

Differentiation and metabolism of adipose tissue are modulated by thyroid hormones (THs), but relatively little is known about the metabolism of THs in this tissue. Expression of the genes for type I iodothyronine 5'-deiodinase (D1), leptin (LEP) and stearoyl-CoA desaturase 1 (SCD-1) was evaluated in omental (OM) and subcutaneous (SC) fat using a cohort of 70 humans. Activities of iodothyronine deiodinases (D1, D2 and D3) were assessed in a randomly selected subpopulation of 19 subjects. D1 expression was upregulated in both OM (P=0.011) and SC (P=0.003) fat of obese subjects. Concomitantly, OM (P=0.002) and SC (P=0.028) LEP expression were increased in obesity, associated with both D1 mRNA (r=0.315, P=0.014) and activity (r=0.647, P=0.023) and inversely related to SCD-1 (r=-0.266, P=0.034) expression in SC fat. Also D1 (but not D2 and D3) activity was increased in OM (∼fourfold, P=0.010) and SC (∼eightfold, P=0.004) fat of obese when compared with non-obese subjects and correlated in both OM (r=0.528, P=0.036) and SC (r=0.749, P=0.005) fat with body mass index. Our results document increased D1 gene expression and activity in adipose tissue of obese humans and suggest a role of 3,5,3'-triiodo-L-thyronine formed by D1 in response to leptin in the modulation of adipose tissue metabolism.

Effect of exercise performed at anaerobic threshold on serum growth hormone and body fat distribution in obese patients with type 2 diabetes

The mechanism by which exercise reduces visceral fat is not fully understood. We have reported that increase in serum growth hormone (GH) level by mild exercise is associated with increase in lipolysis in type 2 diabetes (T2D), and that GH stimulates lipolysis in rat visceral adipose tissue. The aim of this study was to investigate the effect of GH secretion in response to exercise on visceral fat in obese subjects with T2D. Subjects were divided into exercise (n = 11) and non-exercise (n = 8) groups. Exercise was performed at anaerobic threshold (AT). Blood samples were obtained at weeks 0 and 4. To evaluate the secretion of GH and catecholamines in response to exercise, serum GH and catecholamines levels were measured before and after a bout of exercise on day 1. Visceral fat area (VFA) reduction tended to be greater in exercise group compared to non-exercise group (p = 0.067), whereas subcutaneous fat area (SFA) reduction was not different between two groups. In exercise group, serum GH level tended to increase during exercise, while catecholamines showed no significant changes. The change in serum GH level correlated negatively with the change in VFA during this study, but did not correlate with SFA. The increase in serum insulin-like growth factor-I level in exercise group was 10-fold higher than that in non-exercise group. These results suggest that in obese patients with T2D, exercise performed at AT may reduce visceral fat and the reduction appears to be associated with GH secretion but not with catecholamine in response to exercise.:

Efficacy of low-calorie, partial meal replacement diet plans on weight and abdominal fat in obese subjects with metabolic syndrome: a double-blind, randomised controlled trial of two diet plans - one high in protein and one nutritionally balanced

Little is known about the relative efficacy of high-protein vs. conventional diet plans that include partial meal replacements on body fat loss in obese subjects with metabolic syndrome. We aimed to evaluate the efficacy of two low-calorie diets with partial meal replacement plans-a high-protein plan (HP) and a nutritionally balanced conventional (C) plan-on reducing obesity in obese subjects with metabolic syndrome. In a 12-week, double-blind study, we randomised 75 participants to either the HP- or the C-plan group. We recorded key metrics at 0 and 12 weeks. The overall mean weight loss was 5 kg in the HP-plan group and 4.9 kg in the C-plan group (p = 0.72). Truncal fat mass decreased 1.6 kg in the HP-plan group (p < 0.05) and 1.5 kg in the C-plan group (p < 0.05), while whole body fat mass decreased 2.5 kg in the HP-plan group (p < 0.05) and 2.3 kg in the C-plan group (p < 0.05). Between-group losses did not differ significantly for truncal (p = 0.52) or whole body (p = 0.77) fat mass. Among subjects with > or = 70% dietary compliance, however, truncal and whole body fat mass decreased more in the HP-plan group (Delta 2.2 kg and Delta 3.5 kg respectively) than in the C-plan group (Delta 1.3 kg and Delta 2.3 [corrected] kg respectively) (p < 0.05). The HP- and C-plans had a similar effect on weight and abdominal fat reduction, but the HP-plan was more effective in reducing body fat among compliant subjects.

Increase in endoplasmic reticulum stress-related proteins and genes in adipose tissue of obese, insulin-resistant individuals.

OBJECTIVE—To examine fat biopsy samples from lean insulin-sensitive and obese insulin-resistant nondiabetic individuals for evidence of endoplasmic reticulum (ER) stress.RESEARCH DESIGN AND METHODS—Subcutaneous fat biopsies were obtained from the upper thighs of six lean and six obese nondiabetic subjects. Fat homogenates were used for proteomic (two-dimensional gel and MALDI-TOF/TOF), Western blot, and RT-PCR analysis.RESULTS—Proteomic analysis revealed 19 differentially upregulated proteins in fat of obese subjects. Three of these proteins were the ER stress–related unfolded protein response (UPR) proteins calreticulin, protein disulfide-isomerase A3, and glutathione-S-transferase P. Western blotting revealed upregulation of several other UPR stress–related proteins, including calnexin, a membrane-bound chaperone, and phospho c-jun NH2-terminal kinase (JNK)-1, a downstream effector protein of ER stress. RT-PCR analysis revealed upregulation of the spliced form of X-box binding protein-1s, a potent transcription factor and part of the proximal ER stress sensor inositol-requiring enzyme-1 pathway.CONCLUSIONS—These findings represent the first demonstration of UPR activation in subcutaneous adipose tissue of obese human subjects. As JNK can inhibit insulin action and activate proinflammatory pathways, ER stress activation of JNK may be a link between obesity, insulin resistance, and inflammation.

Can EGCG Reduce Abdominal Fat in Obese Subjects?

Objective: To evaluate metabolic effects of epigallocatechin gallate (EGCG) supplementation when combined with a program of regular aerobic exercise in overweight/obese post-menopausal women.Methods: Thirty-eight overweight or obese postmenopausal women exercised at moderate intensity, viz. walking three times per week for 45 min at 75% of age-predicted maximum heart rate (HR), and took a 150 mg capsule of EGCG (Teavigo®) or placebo (lactose) twice daily for 12 weeks. Blood parameters (lipids, glucose and insulin), blood pressure, heart rate, arterial function and anthropometry were assessed at 0, 6 and 12 wk. At wk 0 and 12, body composition was assessed by dual energy X-ray absorptiometry (DXA) and abdominal fat was assessed by DXA and computed tomography (CT).Results: Waist circumference (p < 0.01), total body fat (p < 0.02), abdominal fat (by DXA) (p < 0.01) and intra abdominal adipose tissue (by CT) (p < 0.01) were reduced in both treatment groups, with no difference between placebo and Teavigo®. Teavigo® significantly decreased resting HR (p < 0.01) and reduced plasma glucose in subjects with impaired glucose tolerance (p < 0.05).Conclusions: Moderate consumption of EGCG can improve the health status of overweight individuals undergoing regular exercise by reducing HR and plasma glucose concentrations. Loss of body fat, however, may require a higher intake of EGCG, other catechins or addition of metabolic stimulants.

A polymorphism in the adiponectin gene influences adiponectin expression levels in visceral fat in obese subjects

Reduced serum adiponectin levels have been found in obesity and type 2 diabetes and variations in the adiponectin gene (APM1) have been associated with type 2 diabetes and features of the metabolic syndrome in different populations. Here, we investigated the expression of APM1 in adipose tissue and studied the relationship between variation in APM1 expression, the APM1 G276T polymorphism, the common PPARG Pro12Ala polymorphism and clinical features of 36 morbidly obese (body mass index (BMI) 41.5 +/- 4.9 kg/m2) nondiabetic subjects. APM1 mRNA expression in visceral fat was correlated with serum adiponectin levels (r = 0.54, P = 0.012). In visceral, but not in subcutaneous, adipose tissue APM1 mRNA level was 38% higher among carriers of the APM1 G276T T allele (G/T and T/T) than among carriers of the G/G genotype (0.91 +/- 0.06 for G/T and T/T carriers vs 0.66 +/- 0.09 for G/G carriers, P = 0.013). Carriers of the T allele also had significantly higher body fat percent compared to G/G carriers (65 +/- 6 vs 56 +/- 10%, P = 0.011). Our results indicate that genetic variation in APM1 influences the expression of the gene in visceral adipose tissue and suggest a potential role for such variation in regulation of body fat accumulation in obese subjects.

The effect of an increased free fatty acid concentration on thermogenesis and substrate oxidation in obese and lean men

To examine whether a certain increase in plasma free fatty acid (FFA) concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men. The study protocol consisted of a 30 min baseline period after which subjects received an i.v. bolus of 1000 IE heparin. Then consecutive infusions of 4.9, 9.8 and 19.6 microl/kg fat-free mass (FFM).min of a lipid heparin mixture were started, each infusion for 30 min. Eleven obese and 13 lean men with a mean body mass index (BMI) of 34.2+/-1.0 (+/-s.e.m.) and 23.9+/-0.5 kg/m(2) and age 46.0+/-1.0 and 42.6+/-1.5 y, respectively. Energy expenditure, respiratory exchange ratio (RER) and carbohydrate and lipid oxidation were continuously measured by indirect calorimetry. At the end of each infusion period, a blood sample was taken for FFA, glycerol, insulin, beta-hydroxybutyrate, noradrenaline and adrenaline determination. At baseline, plasma FFA levels were comparable in both groups. Lipid heparin infusion increased plasma FFA concentration by 301+/-47 micromol/l and 332+/-27 micromol/l in obese and lean men. Energy expenditure increased similarly in obese and lean men (0.34+/-0.08 vs 0.40+/-0.08 kJ/min, NS) during lipid heparin infusion, whereas RER decreased similarly in both groups. Lipid oxidation rates were comparable at baseline and increased similarly in obese and lean men (19+/-5 vs 13+/-4 mg/min, NS). Baseline plasma insulin levels were higher in the obese, but did not change during lipid heparin infusion. Plasma beta-hydroxybutyrate concentrations were similar at baseline, but increased significantly less in the obese during lipid heparin infusion. Baseline noradrenaline and adrenaline concentrations did not differ significantly between groups. During lipid heparin infusion, plasma noradrenaline levels decreased significantly, but plasma adrenaline levels remained unchanged in both groups. A certain increase in plasma FFA concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men. The accumulation of fat in obese subjects may therefore be more likely to be due to a defect in adipose tissue lipolysis than a defect in lipid oxidation. International Journal of Obesity (2001) 25, 33-38

Validity of skinfold and girth based regression equations for the prediction of body composition in obese adults.

The validity of generalized and obese population-specific body composition prediction equations for estimating percent fat was examined. Thirty-eight clinically obese women (mean ± SD, % fat = 46.4 ± 5.2%, body mass = 97.2 ± 17.7 kg, age = 41.8 ± 13.3 years) and 16 clinically obese men (% fat = 39.2 ± 3.8%, body mass = 126.7 ± 24.6 kg, age = 43.0 ± 11.6 years) had % body fat estimated by hydrostatic weighing (with RV measured) and had a series of skinfold and girth-based prediction equations applied to estimate % fat. The equations were chosen because they were said to be "generalized" or because they were "population specific" to obese samples of subjects. Results of the present study indicated that the majority of prediction equations were not valid estimators of % body fat in obese males and females. Of the equations that were valid estimators of % body fat (mean differences in % fat of < 3%, r ≥ 0.70, SE < 5%), all but one (Lohman, 1981) utilized girths as part of the prediction technique. It was concluded that generalized girth-based equations could be utilized for prediction of % body fat in obese subjects.

Effect of Exercise and the Specific Dynamic Action of Fat in Obese Subjects.

The effect of a meal containing 100 gm. of butter and 50 gm. of olive oil mayonnaise, alone, and with exercise, has been determined in 2 normal and 4 non-diabetic obese subjects. The metabolism was determined by collection and analysis of the expired air; after determining the basal metabolic rate the subjects were usually exercised while still in the post-absorptive state and before the ingestion of the fat meal; this gave the post-absorptive metabolism both at rest and in exercise. They were then given the 150 gm. of fat and the resting and exercise metabolism was determined, usually once an hour for 7 to 8 hours. The exercise consisted of having the subject lift the lower extremities, while lying on the back and connected with the spirometer, rhythmically and alternately so as to touch with the toes a board placed a given distance above the foot of the bed. The rhythm was maintained by the use of a metronome which was usually set at about 76 beats per minute, so that a lower extremity was lifted 19 times per minute. This exercise increased the metabolism from 2 to 3 times. The subjects exercised for 2 minutes before collection of the expired air was begun; and this was continued for 5 or 6 minutes, depending on the degree of fatigue produced. In 2 normal subjects and one of the obese there was a slight initial rise in the resting respiratory quotient following the ingestion of the fat; this was followed by a gradual fall, which, at the end of 6 to 7 hours reached a level lower than the resting quotient.