Biomedical subjects

P Imbeault

Publications and source records attributed to P Imbeault.

At least 19 recordsLinked to original sources

PubMed2004

Thermogenesis and weight loss in obese individuals: a primary association with organochlorine pollution.

The main objective of this study was to investigate the potential impact of body organochlorine (OC) pollution on the adaptive change in thermogenesis induced by body weight loss. Fat mass (FM), fat-free mass (FFM), and sleeping metabolic rate (SMR) were measured in obese individuals before and after a weight-reducing program. The measured values of SMR were then compared to those predicted from a reference equation established from FM and FFM in control subjects. Plasma OC, leptin, total tri-iodothyronine, and free thyroxine concentrations were also measured in obese subjects before and after weight loss. After weight loss, the measured decrease in SMR was greater than that predicted by changes in FM and FFM. Increased plasma OC concentration was the factor explaining the greatest proportion of the difference between predicted and measured SMR changes induced by body weight loss. OC pollution seems to be a new factor affecting the control of thermogenesis in some obese individuals experiencing body weight loss.

Adult↗

PubMed2003

Energy balance and pollution by organochlorines and polychlorinated biphenyls.

Organochlorines are fat-soluble chemical compounds resistant to degradation, so they are stored in the adipose tissue of practically every organism on the planet, including humans. Accumulation of these compounds in the body seems to be related to fat mass, obese individuals having a higher plasma organochlorine concentration than lean subjects. During body weight loss, lipid mobilization and a decrease in fat mass result in increased concentrations of organochlorines in plasma and adipose tissue. Organochlorines may have adverse health effects. For example, they have been associated with altered immune and thyroid functions and with some types of cancer. As these compounds may reach their target organs whilst in the circulation, their increase in plasma during weight loss might be associated with some physiological changes occurring during weight loss. Relationships have indeed been reported among weight loss-induced increase in plasma organochlorine concentration and decreased triiodothyronine (T3) concentration, resting metabolic rate, and skeletal muscle markers for fat oxidation. Although further studies are needed to assess the causality of these relationships, they raise concern about some potential undesirable effects of weight loss. Indeed, the effects of organochlorines on energy balance could complicate body weight loss and even favour weight regain. These notions lend support for weight-loss strategies favouring a moderate weight loss, which would reduce risks for cardiovascular diseases, diabetes and hypertension, without resulting in a substantial release of organochlorines.

Adipose Tissue↗

PubMed2002

Reduction of visceral adipose tissue during weight loss.

OBJECTIVE: The aims of the present study were to retrospectively: (1) compare how weight loss affects the reduction of adipose tissue from three different sites between men and women; and (2) to verify whether gender differences in the reduction of adipose tissue are influenced by changes in fat mass (FM) and initial levels of fat in different compartments. DESIGN: Double-blind randomized treatment with fenfluramine once daily coupled to a non-macronutrient specific energy restriction. SUBJECTS: Seventeen obese men (age 43.9+/-1.5 and body mass index (BMI) 34.3+/-0.7) and 17 obese women (age 41.2+/-1.2 and BMI 35.7+/-0.6). INTERVENTIONS: Subjects were given fenfluramine (60 mg) or placebo once daily and were also subjected to a non-macronurient specific energy restriction of -2.9 MJ/day (-700 kcal/day) for 15 weeks. RESULTS: Body weight, FM, fat-free mass (FFM), waist circumference, BMI, as well as visceral (VAT), subcutaneous abdominal (SAT) and thigh (TAT) adipose tissue were all significantly reduced. Men lost significantly more VAT (-41.6%) than SAT (-22.5%), or than TAT (-20.5%) while no site difference in fat loss was observed in women when changes were calculated as a percentage of initial levels. Men lost about twice as much fat from the VAT compartment than did women (P<0.05), even after having considered changes in FM as a potential covariate. In absolute values, TAT was reduced to a lesser extent in men than in women. However, when initial levels of respective fat depots were also taken into account, gender differences in VAT and TAT loss were no longer statistically significant. CONCLUSION: These results suggest that gender differences in VAT reduction during weight loss are independent of changes in FM. However, once initial levels of VAT are also taken into account, gender differences in the reduction of this tissue during weight loss are no longer apparent.

Adipose Tissue↗

PubMed2002

Increase in plasma pollutant levels in response to weight loss is associated with the reduction of fasting insulin levels in men but not in women.

Environmental pollutants can act as endocrine modulators. In this study, we examined whether weight loss-induced changes in plasma organochlorine compounds (OC) were associated with those in plasma insulin levels. Fasting insulin and the area under the curve (AUC) of insulin after a 75-g oral glucose load, plasma levels of 1 commercial polychlorinated biphenyl (PCB) mixture (Aroclor 1260), 1 PCB congener (PCB 153), and 3 pesticides (2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), beta-hexachlorocyclohexane (beta-HCH), and hexachlorobenzene (HCB)) were measured before and after a 15-week weight loss program induced by a caloric restriction in a sample of obese men and women. Both genders showed a similar reduction in body weight (approximately 11 kg) in response to treatment, although men lost significantly more fat mass than women (mean +/- SD 9.4 +/- 4.1 v 5.9 +/- 5 kg, respectively, P <.05). Fasting insulin and AUC of insulin significantly decreased in men and women after the treatment. In response to weight loss, a significant increase in OC was observed in both genders, and this effect was more pronounced in men. The greater the increase in plasma OC levels, the greater the reduction in fasting insulin was in response to weight loss in men (-.49 < r < -.59, P <.05), but not in women (-.22 < r <.01, not significant [NS]). In both genders, no relationship was observed between changes in plasma OC levels and changes in AUC of insulin (-.41 < r < -.08, NS). In men, relationships between changes in plasma HCB, Aroclor 1260, and PCB-153 concentrations and those in fasting insulin levels in response to weight loss remained significantly correlated after correction for fat mass loss (-.46 < partial r < -.51, P values ranging from.05 to.07). These results suggest that weight loss-induced increase in plasma pollutant levels tends to be independently associated with the reduction of fasting insulin levels in men, but not in women. Further studies are needed to verify whether these findings are causally related.

Adipose Tissue↗

PubMed2001

Increase in plasma pollutant levels in response to weight loss in humans is related to in vitro subcutaneous adipocyte basal lipolysis.

OBJECTIVE: To examine whether weight loss-induced changes in in vitro basal lipolysis of subcutaneous abdominal and femoral fat cells were related to those in plasma organochlorine levels. DESIGN: A 15 week weight loss program induced by a moderate caloric restriction. SUBJECTS: Seventeen men and 20 women (age 36-50 y, body fat 25-50%). MEASUREMENTS: In vitro basal lipolysis of subcutaneous abdominal and femoral adipocytes and plasma levels of five polychlorinated biphenyl congeners (Aroclor 1260, PCBs 118, 138, 153 and 180) and three chlorinated pesticides (dichlorodiphenyl dichloroethene (p,p'-DDE), beta-hexachlorocyclohexane (beta-HCH) and hexachlorobenzene (HCB)) were measured before and after the weight reducing program. RESULTS: Both genders showed a similar reduction in body weight (approximately 11 kg) in response to treatment, although men lost significantly more fat mass than women (mean+/-s.d., 9.4+/-4.1 vs 5.9+/-5 kg, respectively, P<0.05). Mean basal fat cell lipolysis did not vary before and after weight reduction, regardless of depots and genders. In response to weight loss, significant increases of all organochlorines investigated were observed in men, whereas only p,p'-DDE, Aroclor 1260, PCBs 153 and 180 significantly rose in women. In men, higher the increase in basal lipolysis of subcutaneous abdominal or femoral adipocytes, greater the rise in plasma levels of most pollutants (HCB, Aroclor 1260, PCBs 118, 138 and 153) was in response to weight loss (0.51<r<0.70, P<0.05). Similar positive correlations were also observed in women but only a few reached statistical significance (p,p'-DDE, PCBs 118 and 180). CONCLUSION: The weight loss-induced increase in plasma pollutant levels is related to the rise in subcutaneous abdominal and femoral adipocyte basal lipolysis, especially in men.

Abdomen↗

PubMed2001

Difference in leptin response to a high-fat meal between lean and obese men.

The aim of this study was to compare the leptin responses to a high-fat meal in lean and obese men, and to investigate whether the net leptin response (area under the incremental curve) after the meal was related to the thermic effect of food (TEF). Blood samples were collected after an overnight fast and every 2 h for 8 h after a high-fat breakfast (60 g of fat/m(2) body surface area) in 12 lean and 12 obese men for determination of glucose, insulin and leptin. The TEF was calculated as postprandial energy expenditure minus fasting energy expenditure, as measured by indirect calorimetry. Fasting plasma glucose levels were similar in lean and obese men, and increased in the same way after the meal. Fasting and postprandial plasma insulin concentrations were significantly greater in obese than in lean men (P<0.01 and P<0.05 respectively). Accordingly, obese men showed a significantly higher net insulin response than lean subjects (P<0.001). Fasting plasma leptin levels were greater in obese than in lean men (P<0.001). After the meal, plasma leptin increased significantly in lean men, whereas it decreased in obese men (group by time interaction, P<0.01). The net response of leptin was greater in lean than in obese men, but this did not reach statistical significance (P=0.07). Moreover, the TEF was similar in the two groups. No significant relationship was observed between either the net insulin response or the net leptin response after the high-fat meal and the TEF of lean subjects (-0.05 <r<0.31). In obese men, the net response of insulin was correlated significantly with TEF (r=0.70, P<0.05), whereas the net response of leptin was not (r=-0.40). These results suggest that obesity is related to an impaired regulation of leptin by insulin, since leptin levels increased in lean men but decreased in obese men following a high-fat meal. Moreover, the fact that the postprandial leptin responses of both lean and obese men were not significantly related to the TEF suggests that the ob gene product is probably not acutely involved in the control of this energy expenditure component in humans.

Adult↗

PubMed2001

Elevated intramyocellular lipid concentration in obese subjects is not reduced after diet and exercise training.

To determine the effects of weight loss on intramyocellular energy substrates, vastus lateralis muscle biopsies were taken from six obese subjects (body mass index 34 +/- 5 kg/m(2)) before, after 15 wk of energy restriction (ER; -700 kcal/day), and after a further average 20.7 +/- 1.6 wk of endurance training plus low-fat diet (ET-LFD). Body weight fell from 100 +/- 6 to 89 +/- 6 kg during ER and to 84 +/- 4 kg after ET-LFD. Lipids and glycogen were histochemically measured in type I, IIA, and IIB fibers. Total muscle glycogen content (MGC; per 100 fibers) decreased after ER [from 72 +/- 13 to 55 +/- 8 arbitrary units (AU)]. A similar but not significant decrease was seen in total muscle lipid content (MLC; 14 +/- 5 to 9 +/- 1 AU). After ET-LFD, MGC returned to initial values (74 +/- 8 AU), and MLC approached near-initial values (12 +/- 3 AU). Individual fiber lipid concentration did not change throughout the protocol in all fiber types, whereas glycogen concentration increased after ET-LFD. The training effects of ET-LFD were measured as increasing activities of key mitochondrial enzymes. Although total muscle energy reserves can be reduced after weight loss, their concentration within individual myofibers remains elevated. Weight loss does not appear sufficient to correct the potential detrimental effects of high intracellular lipid concentrations.

Adult↗

PubMed2001

Age-related differences in messenger ribonucleic acid expression of key proteins involved in adipose cell differentiation and metabolism.

This study was performed to compare the expression of key proteins [lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), complement 3 (C3), and peroxisome proliferator-stimulated receptor-gamma (PPAR gamma)] involved in sc abdominal adipose tissue (AT) metabolism of young (n = 13) vs. middle-aged (n = 16) men. The sc abdominal AT-LPL activity as well as fat cell lipolysis were also measured in both groups of men. Young and middle-aged men displayed similar body weight and sc abdominal fat accumulation, measured by computed tomography. However, middle-aged men were characterized by a higher percent body fat (28 +/- 5% vs. 22 +/- 7%; P < 0.05) than young subjects. No difference between groups was observed in sc abdominal adipose tissue LPL activity. On the other hand, maximal lipolytic responses of sc abdominal adipocytes to isoproterenol (beta-adrenergic agonist) or to postadrenoceptor agents such as dibutyryl cAMP, forskolin, and theophylline were lower in middle-aged than in young men (P < 0.05). AT-LPL messenger ribonucleic acid (mRNA) levels were similar regardless of the subject's age. However, HSL, C3, and PPAR gamma mRNA levels were higher in middle-aged than in young individuals (P < 0.01-0.05). After correction for percent body fat, only HSL and C3 mRNA levels remained significantly different between groups (P < 0.05). Taken together, these results suggest that aging has an effect on the up-regulation of HSL and C3 mRNA levels, whereas PPAR gamma expression seems to be related mainly to increased adiposity.

Abdomen↗

PubMed2000

Hyperleptinemia is more closely associated with adipose cell hypertrophy than with adipose tissue hyperplasia.

OBJECTIVES: To investigate the relationships of fat cell weight (FCW) as well as of estimated total adipose cell number to fasting plasma leptin concentration. DESIGN: Cross-sectional correlational study. SUBJECTS: A sample of 63 men (mean age+/-s.d.: 36+/-4 y) and 42 premenopausal women (35+/-5 y). MEASUREMENTS: Adipose tissue (AT) biopsies were obtained in order to determine FCW as well as estimated adipose cell number. Fasting plasma leptin and insulin concentrations as well as various fatness and body fat distribution variables (underwater weighing and computed tomography) were also measured. RESULTS: In both genders, mean FCW as well as the estimated adipose cell number were significantly correlated with body fatness and AT distribution variables (0.41</=r</=0.84). Larger abdominal (P<0.005) and femoral (P<0.0001) FCW were found in women than in men. This gender difference in adipose cell size was associated with increased leptin concentrations in women compared with men. In both genders, increased abdominal FCW was associated with higher plasma leptin concentrations (men: r=0.38, P<0.005 and women: r=0.55, P<0.0001). However, the association between femoral FCW and leptinemia was only significant in women (r=0.45, P<0.005). Contrary to women, plasma leptin concentrations were associated with estimated adipose cell number in men (r=0.59, P<0.0001). Multiple regression analyses revealed that gender (43.3%), mean FCW (16.2%) and the estimated adipose cell number (10.1%) were significant predictors of fasting leptinemia. CONCLUSIONS: Results of the present study indicate that in men and women, adipose cell hypertrophy is associated with increased plasma leptin concentrations. This finding provides further support to the observation that adipose tissue leptin secretion may be regulated, at least to a certain extent, by adipocyte size. Thus, the present study suggests that the higher plasma leptin concentrations found in women than in men could be partly explained by the well documented gender difference in adipose cell size and number.

Adipocytes↗

PubMed2000

Appetite after weight loss by energy restriction and a low-fat diet-exercise follow-up.

OBJECTIVE: The aim of the present study was to determine the impact of weight loss on appetite as measured by visual analog scale (VAS). METHODS: Seventeen subjects (10 men and seven women) took part in a 15 week weight loss program which consisted of drug therapy (fenfluramine 60 mg/day) or placebo coupled to an energy restriction (-2930 kJ/day; phase 1) followed by an 18 week low-fat diet-exercise follow-up (phase 2). Subjects were given a standardized breakfast before and after phase 1 as well as after phase 2. Individuals were asked to fill out VAS before and at 0, 10, 20, 30, 40, 50 and 60 min after this test meal. Blood samples were drawn before the meal and at 0, 30 and 60 min postprandially and analyzed for glucose and insulin. Fasting plasma cortisol and leptin were also determined. RESULTS: An increase in the fasting desire to eat, hunger and prospective food consumption (PFC) was observed after phase 1 and to an even greater extent after phase 2 in both men and women. In the fasting state, positive correlations were observed between changes in the desire to eat (r=0.76; P<0.05) as well as changes of PFC (r=0. 82; P<0.05) and changes in cortisol at the end of phase 1 for women. In response to phase 1, statistically significant correlations were found between changes of hunger (r=0.64; P<0.05) and desire to eat (r=0.67; P<0.05) as measured by AUC in response to the meal and changes of fasting plasma cortisol in men. The most consistent predictor of changes of baseline desire to eat (r=0.68 P<0.05), fullness (r=-0.78, P<0.05) and PFC (r=0.91, P<0.01) during phase 2 was the change in fasting cortisol in men. Changes of fullness were also associated with changes of fasting leptin in men (r=0.68; P<0. 05) during phase 2. CONCLUSION: These results suggest that weight loss is accompanied by an increase of baseline appetite in both men and women and that the most consistent predictor of these changes in appetite seems to be changes in fasting plasma cortisol.

Adult↗

PubMed2000

beta-adrenoceptor-stimulated lipolysis of subcutaneous abdominal adipocytes as a determinant of fat oxidation in obese men.

BACKGROUND: To verify whether an impaired lipolytic capacity of subcutaneous adipocytes may contribute to low rate of fat oxidation. DESIGN: Relationships between adipose tissue lipolysis of subcutaneous (subc) abdominal and femoral isolated adipocytes and respiratory quotient (RQ) were investigated in 20 obese men (age: 44 +/- 5 years; means +/- SD) studied in a fasting state. RESULTS: Maximal isoproterenol-induced lipolysis was greater in subcutaneous abdominal than in femoral fat cells even if glycerol release was corrected for variation in cell surface area (P < 0.01). On the other hand, no regional variation was observed in the adipose cell lipolytic responses to postadrenoceptor agents such as dibutyryl-cyclic AMP, forskolin and theophylline. Maximal isoproterenol-induced lipolysis of subc abdominal, but not of femoral adipocytes, was inversely related to RQ (r = - 0.61; P < 0. 01) and positively associated to fat oxidation (r = 0.57; P < 0.01). These relationships were independent of possible confounding factors such as fat mass, fat-free mass, waist girth and subc abdominal adipose tissue accumulation assessed by computed tomography, as maximal isoproterenol-induced lipolysis of subcutaneous abdominal adipocytes was the only variable retained as a significant predictor of RQ levels (38% of variance) and of fat oxidation (30% of variance). CONCLUSION: These results suggest that adipose tissue lipolytic activity of subc abdominal adipocytes acts as a determinant of fat oxidation in obese men.

Abdomen↗

PubMed2000

Subcutaneous adipose tissue metabolism at menopause: importance of body fatness and regional fat distribution.

The aim of this study was to examine the contribution of menopause per se on sc adipose tissue (AT) metabolism in 16 women classified on the basis of their menopausal status: 8 postmenopausal (mean +/- SD age, 57 +/- 6 yr) vs. 8 premenopausal individuals (37 +/- 5 yr). These 2 groups were matched for sc abdominal adipose cell size (within 0.02 microg lipid/cell) and visceral AT accumulation (within 15 cm2), measured by computed tomography. Fasting plasma glucose and insulin levels as well as their responses to an oral glucose load were similar regardless of the women's hormonal status. Subcutaneous abdominal and femoral AT lipoprotein lipase activities as well as fat cell lipolysis were determined in both groups. Epinephrine induced antilipolysis at low concentrations and lipolysis at higher doses in both adipose sites and groups. The maximal lipolytic response to epinephrine or to isoproterenol (beta-adrenergic agonist) as well as the maximal antilipolytic effect of either the catecholamine or UK-14304 (alpha2-adrenergic agonist) assessed in sc adipocytes were similar in pre- and postmenopausal women. In addition, neither the beta- nor the alpha2-adrenoceptor sensitivity of sc adipose cells differed according to subjects' age. Finally, maximal lipolysis promoted by postadrenoceptor agents and AT-lipoprotein lipase activity did not vary among adipose regions or between groups. Taken together, these results suggest that menopause per se does not influence sc AT metabolism once the variation related to adipose cell size and total body fatness is taken into account.

Adipocytes↗

PubMed2000

Adipose tissue metabolism in young and middle-aged men after control for total body fatness.

The aim of this study was to compare the sc adipose tissue metabolism of young (29 +/- 4 yr) vs. middle-aged men (57 +/- 5 yr), once the concomitant variation in total adiposity was taken into account. For this purpose, sc abdominal and femoral adipose tissue lipoprotein lipase activities, as well as fat cell lipolytic responses, were investigated in 2 groups of 16 men, differing in age but displaying similar adipose tissue mass (within 2 kg) and sc abdominal adipose tissue area, measured by computed tomography (within 15 cm2). No difference was observed in adipose tissue lipoprotein lipase activity of young vs. middle-aged subjects, regardless of the adipose region considered. Epinephrine induced antilipolysis at low concentrations (10(-9) to 10(-7) mol/L) and a net lipolytic response at higher doses (10(-6) to 10(-5) mol/L), regardless of the subjects' age and the anatomic location of fat. In addition, the selective alpha2-adrenergic agonist, UK-14304, promoted a similar antilipolytic response in sc abdominal and femoral adipose cells from both groups. However, maximal lipolysis induced by isoproterenol (beta-adrenergic agonist) or by postadrenoceptor agents such as dibutyryl-cAMP, forskolin, and theophylline were lower in both adipose regions of middle-aged (as compared with young) men. No difference in the beta- or the alpha2-adrenoceptor sensitivity of sc adipose cells was observed between groups. These results indicate that there is, with age, a selective decrease in the lipolytic capacity to beta-adrenergic agonist, which seems to be caused by postadrenoceptor impairments. Because subjects in the 2 age-groups displayed similar body fatness, these alterations are independent from the age-expected increase in total adiposity.

Adipose Tissue↗

PubMed2000

Reduced alpha(2)-adrenergic sensitivity of subcutaneous abdominal adipocytes as a modulator of fasting and postprandial triglyceride levels in men.

This study examined the postprandial lipemia of two groups of men displaying similar age, body weight, and regional fat distribution, but characterized by either low (n = 11) or high (n = 15) alpha(2)-adrenergic sensitivity of subcutaneous abdominal adipocytes. In addition to fat cell lipolysis, adipose tissue lipoprotein lipase (AT-LPL) as well as postheparin plasma LPL activities were measured in the fasting state. Fasting AT-LPL and PH-LPL activities were similar in both groups. Maximal adipose cell lipolysis induced by isoproterenol (beta-adrenergic agonist) as well as the beta-adrenergic sensitivity did not differ between both groups of men. The selective alpha(2)-adrenergic agonist UK-14304 promoted a similar antilipolytic response in subcutaneous abdominal adipocytes from both groups. However, the alpha(2)-adrenergic sensitivity, defined as the dose of UK-14304 that produced half-maximal inhibition of lipolysis (IC(50)), was significantly different between groups (P < 0.0001). Men with low versus high subcutaneous abdominal fat cell alpha(2)-adrenergic sensitivity showed higher fasting TG levels. In the whole group, a positive relationship was observed between log-transformed IC(50) UK-14304 values of subcutaneous adipocytes and fasting TG levels (r = 0.39, P < 0.05), suggesting that a low abdominal adipose cell alpha(2)-adrenergic sensitivity is associated with high TG levels. After the consumption of a high-fat meal, subjects with low subcutaneous abdominal adipose cell alpha(2)-adrenergic sensitivity showed higher TG levels in total, medium, and small triglyceride-rich lipoprotein (TRL) fractions at 0- to 6-h time points than men with high adipocyte alpha(2)-adrenergic sensitivity (P values ranging from 0.01 to 0.05). Stepwise regression analysis showed that the fasting TG concentration was the only variable retained as a significant predictor of the area under the curve of TG levels in total TRL fractions (73% of variance) among independent variables such as body weight, percent body fat, visceral and subcutaneous abdominal adipose tissue accumulation measured by CT, as well as subcutaneous abdominal fat cell alpha(2)-adrenoceptor sensitivity. Taken together, these results indicate that a reduced antilipolytic sensitivity of subcutaneous abdominal adipocytes to catecholamines may increase fasting TG levels, which in turn play a role in the etiology of an impaired postprandial TRL clearance in men.

Abdomen↗

PubMed1999

Physical activity and low-fat diet: is it enough to maintain weight stability in the reduced-obese individual following weight loss by drug therapy and energy restriction?

OBJECTIVE: The anthropometric and physiological effects of a physical activity (PA) and a mildly energy-restricted low-fat diet (LFD) follow-up program after a long-term dietary restriction were studied in 12 men and 8 women. RESEARCH METHODS AND PROCEDURES: The dietary restriction (approximately 700 kcal/day) was accompanied by a fenfluramine (60 mg/day) or placebo treatment for 15 weeks, whereas the mean duration of the PA-LFD follow-up was 18 weeks. RESULTS: The long-term dietary restriction reduced body weight (-11.9 and -7.6 kg, p<.001), fat mass (FM) (-10.6 and -5.8 kg, p<0.01), resting metabolic rate (RMR) (-304 kcal/day, p<0.01 and -148 kcal/day, NS) in men and women, respectively. A decrease in fat-free mass (FFM) was also observed in women (-1.8 kg, p<0.05). The PA-LFD follow-up preserved weight stability at a reduced body weight and caused an additional significant decrease in FM for men (-3.4 kg, p<0.05). This part of the intervention also caused an increase in daily RMR for men (134 kcal/day, NS) to the point where this value no longer differed from the pre-energy restriction value. In contrast, RMR was further reduced in women (-200 kcal/day) to the point where it significantly differed from initial values (p<0.01). Resting seated heart rate was reduced by the PA-LFD follow-up in men leading it to differ significantly from both pre- and post-energy restriction values (-8.5 and -5.5 bpm, p<0.01). DISCUSSION: In conclusion, these results suggest that a PA-LFD follow-up has the potential to permit body weight stability and may even accentuate fat loss in the reduced-obese state. Moreover, resting energy expenditure is increased under such conditions in men. These stimulating effects seem to be specific to energy metabolism since seated heart rate was either further reduced or remained stable in response to the PA-LFD follow-up.

Adult↗

PubMed1999

Metabolic fitness in active reduced-obese individuals.

OBJECTIVE: To verify whether a physical activity-low-fat diet follow-up could normalize the metabolic risk profile of reduced-obese men and women having undergone considerable weight loss through energy restriction and drug therapy. RESEARCH METHODS AND PROCEDURES: Twenty obese individuals (12 men, 8 women) participated in a weight-reducing program that included two phases. In the first phase, a non-macronutrient-specific dietary restriction of about 700 kcal/day was prescribed to induce weight loss over 15 weeks, with either fenfluramine or placebo. The second phase consisted of a physical activity-low-fat diet follow-up that was maintained as long as subjects did not experience resistance to further body weight and fat loss. Resistance to lose fat occurred after a mean cumulative fat loss of 14 and 8 kg in men and women, respectively. RESULTS: Despite this substantial decrease in body fat, subjects' adiposity remained much higher at the end of this protocol than values observed in lean control subjects. However, fasting plasma levels of insulin, cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and triglyceride as well as the response of insulin and glucose to oral glucose were normalized at the end of the physical activity-low-fat diet follow-up. DISCUSSION: These results indicate that further weight and fat losses may not be justified when a moderate body weight loss resulting in a highly favorable improvement of metabolic risk profile is achieved in patients who would have still been diagnosed as overweight or obese on the basis of criteria currently promoted by public health agencies.

Adult↗

PubMed1999

Relationship of visceral adipose tissue to metabolic risk factors for coronary heart disease: is there a contribution of subcutaneous fat cell hypertrophy?

Visceral adipose tissue (VAT) accumulation is an important correlate of the metabolic complications found in obese patients. The aim of this study was to evaluate the respective contribution of VAT deposition versus subcutaneous abdominal or femoral fat cell hypertrophy as correlates of the metabolic risk profile in 69 men and 65 premenopausal women (aged 35+/-5 years) with a wide range of fatness (body mass index, 18 to 57 kg/m2). In both genders, VAT accumulation was positively correlated with fasting plasma insulin, triglyceride (TG), and low-density lipoprotein (LDL)-apolipoprotein B (apo B) levels and the cholesterol (CHOL)/high-density lipoprotein (HDL)-CHOL ratio (.24 < or = r < or = .71, P < .05). A similar pattern of positive relationships was found between subcutaneous abdominal fat cell weight and metabolic risk variables in men and women (.33 < or = r < or = .60, P < .01). Positive associations were also observed in women between femoral fat cell weight and fasting plasma insulin, TG, and CHOL levels and the CHOL/HDL-CHOL ratio (.29 < or = r < or = .42, P < .05). However, only plasma TG concentrations and the CHOL/HDL-CHOL ratio were positively correlated with femoral fat cell weight in men (r = .30, P < .05). To better investigate the relationships between the metabolic risk profile and hypertrophic subcutaneous obesity, individuals with small versus large subcutaneous abdominal adipocytes were matched according to VAT accumulation. Men with large abdominal fat cells displayed higher plasma TG and LDL-apo B levels compared with men characterized by small abdominal adipocytes (P < .05). Stepwise multiple regression analyses showed that subcutaneous abdominal fat cell weight was the best independent variable predicting plasma TG and LDL-apo B levels in men. No significant difference was found in the metabolic profile of subjects displaying small versus large femoral adipocytes. Taken together, these results suggest that for a given VAT deposition, the presence of hypertrophied subcutaneous abdominal adipocytes in men appears to be associated with further deterioration in the metabolic risk profile. On the other hand, the hypertrophy of femoral adipocytes does not further alter the metabolic complications generally related to obesity in both men and women.

Adipocytes↗

PubMed1999

Physical activity and weight maintenance.

Physical activity is an important component of a weight-reducing program. When combined with a low fat diet, a physical activity program can reduce body weight by 10-15% in individuals complying with the program. However, even in disciplined individuals, resistance to lose fat ultimately occurs generally before the body composition status of the reduced-obese subjects is comparable to that of their lean counterparts. On the other hand, this weight loss is generally sufficient to normalize the risk profile regarding the development of diabetes and heart diseases. Therefore, this suggests that trying to lose weight beyond the threshold of spontaneous resistance to lose fat, may be unnecessary and not feasible. Furthermore, if one also considers the potential risks for health associated with large fat loss, it is probably not relevant to encourage further weight loss in reduced-obese individuals, when their metabolic profile is normalized. It is also important to emphasize that in such a context, the physical activity program must be maintained on a permanent basis to prevent body weight regain.

Body Weight↗