Michel Vermorel

Evaluation of two foot-to-foot bioelectrical impedance analysers to assess body composition in overweight and obese adolescents

The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelectrical impedance analysers (BIA) to assess body composition in overweight and obese adolescents, compared with dual-energy X-ray absorptiometry (DXA) and hand-to-foot (HF) BIA. Body composition was assessed in fifty-three overweight or obese adolescents (BMI 27.9 (SD 4.1) kg/m2; aged 13-16 years) by DXA (Hologic QDR-4500; Hologic Inc., Bedford, MA, USA) and BIA (HF (BIA 101, RJL System, Detroit, IL, USA) and FF (Body Fat Monitor Scale BF-625, Tanita Corporation of America Inc., Arlington Heights, IL, USA; Téfal Bodymaster Vision, Téfal, Rumilly, France)). Bland-Altman tests showed that, compared with DXA, FF-Tanita and FF-Téfal underestimated (P<0.05) fat mass (FM) less than HF-BIA (-1.7 (SD 3.1), -0.7 (SD 5.8) and -2.3 (SD 2.2) kg respectively, P<0.001). However, the limits of agreement between DXA and FF-Tanita or FF-Téfal were much greater than those obtained with HF-BIA (-7.7 and +4.3, - 12.0 and +10.6 v. -2.1 and +6.7 kg respectively). The differences between FM assessed using the FF-Tanita or the FF-Téfal analyser and DXA increased with the waist:hip ratio, and were higher in boys than in girls. The major limiting factor of FF-BIA was the inter-individual variability in FM estimates. In conclusion, FF-BIA and DXA are not interchangeable methods. FF-BIA could be acceptable to assess body composition in large groups of overweight or obese adolescents, but cannot be recommended for body composition assessment in obese subjects because of the large errors in individual estimates.

Effects of 14 weeks of progressive endurance training on energy expenditure in elderly people

Effects of progressive endurance training on energy expenditure (EE) were studied in thirteen elderly sedentary subjects (62.8 (SD 2.3) years) after 7 and 14 weeks of training. Daily EE (DEE) and energy cost of the various usual activities were measured over 48 h by whole-body indirect calorimetry. Free-living DEE (DEEFLC) was calculated from 7 d activity recordings and the energy costs of activities were measured in the calorimeters using the factorial method. DEEFLC did not vary significantly throughout the training period despite the additional energy cost of training sessions (0.60 (SD 0.15) MJ/d), because energy expended during free-living activities (EEACT) decreased by 4.8 (SD 7.1)% (P < 0.05) and 7.7 (SD 8.6)% (P < 0.01) after 7 and 14 weeks of training respectively. Measurements in the calorimeters showed that sleeping metabolic rate transiently increased by 4.6 (SD 3.2)% after 7 weeks of training (P < 0.001) and returned to its initial level after 14 weeks of training. BMR was 7.6 (SD 7.0)% (P < 0.01) and 4.1 (SD 6.1)% (P = NS) higher after 7 and 14 weeks of training respectively, than before training. Likewise, diet-induced thermogenesis increased from 3.7 (SD 2.5) to 7.2 (SD 2.8)% energy intake after 7 weeks of training (P < 0.05), and returned to its initial level after 14 weeks of training (4.2 (SD 2.6)% energy intake). Despite these changes, energy expended during activities and the corresponding DEE did not vary throughout the training period. It was concluded that: (1) DEEFLC remained constant throughout the training period due to a compensatory decrease in free-living EEACT; (2) progressive endurance training induced a transient increase in sleeping metabolic rate, BMR and diet-induced thermogenesis after 7 weeks which was not reflected in the energy expended during activities and DEE.

Effects of environmental temperature on heat production, energy retention, protein and fat gain in early weaned piglets.

1. Six experiments, each involving two groups of six piglets, were designed to study the influence of environmental temperature on heat production, energy retention and protein and fat gain in early weaned piglets. Immediately after weaning, at a mean age of 25 d, the animals were raised in two open circuit respiratory chambers. Each chamber was equipped with a totally wired cage. The piglets were paired-fed and maintained at environmental temperatures of 20, 24 or 28 degrees. Four replicates were used for each temperature. Metabolizable energy, heat production and nitrogen balance were measured during two consecutive periods (A and B), each of 6 d duration. 2. Heat production was higher at 20 degrees than at 24 and 28 degrees during periods A and B. Energy retention was negative during period A, it was positive during period B and increased with temperature. 3. Protein deposition was always positive and independent of environmental temperature. The net efficiency of protein utilization was 0.77. 4. Body fat was mobilized during period A at a higher rate at 20 degrees than 28 degrees. During period B, fat gain increased with increase in temperature. 5. The calculated ME requirement for maintenance amounted to 411 kJ/kg body-weight 0.75 per d at 28 degrees. 6. The critical temperature of early weaned piglets raised in intensive modern housing and fed at about 90% of the ad lib, intake is close to 28 degrees during the first 12 d after weaning.

Net energy value of non-starch polysaccharide isolates (sugarbeet fibre and commercial inulin) and their impact on nutrient digestive utilization in healthy human subjects

The energy value of NSP has been expressed as their metabolizable energy (ME) content. The aim of the present study was to determine whether differences in ME and net energy (NE) contents were similar for insoluble and soluble NSP. Nine healthy young men were offered three diets according to a Latin-square design (3 x 3) with three repetitions: diet C (control), diet B (control + 50 g sugarbeet fibre/d) and diet I (control + 50 g commercial inulin/d). After a 16 d adaptation period to NSP isolate, food intake was controlled (duplicate meal method) and faeces and urine were collected for 8 d. A period of 60 h was devoted to measurement of energy expenditure (EE) by whole-body indirect calorimetry. NSP-isolate ingestion induced significant increases in the number of defecations and stool weight resulting from increases in water, DM and microbial mass excretion. After deduction of microbial N, differences in faecal N excretion between diets were not significantly different. Urinary N excretion was slightly decreased by sugarbeet fibre or commercial inulin ingestion but the N balances for the diets were not significantly different. Diet energy, N and lipid apparent digestibilities decreased by only 1-2%. Commercial inulin was entirely fermented and fermentability of sugarbeet fibre averaged 0.886 (SD 0.117). Sugarbeet fibre and commercial inulin ME values averaged 10.7 (SD 1.2) and 13.0 (SD 2.3) kJ/g DM respectively. NSP-isolate ingestion caused significant (sugarbeet) and nonsignificant (inulin) increases in daily EE. The maintenance NE contents of sugarbeet fibre and inulin averaged 5.0 (SD 5.0) and 11.9 (SD 1.3) kJ/g DM respectively. Differences in maintenance NE contents of NSP isolates were much greater than differences in ME values.

Daily energy expenditure and its main components as measured by whole-body indirect calorimetry in athletic and non-athletic adolescents

The objectives of the present study were to determine whether differences in usual physical activity affect BMR, sleeping energy expenditure (EE), and EE during seated activities between athletic and non-athletic adolescents, and to establish individual relationships between heart rate and EE. Adolescents (n 49, four groups of eleven to fifteen boys or girls aged 16-19 years) participated in the study. Body composition was measured by the skinfold-thickness method and maximum O2 consumption (VO2max) by a direct method (respiratory gas exchange) on a cycloergometer. The subjects each spent 36 h in one of two large whole-body calorimeters. They followed a standardized activity programme including two periods of exercise simulating their mean weekly physical activities. Fat-free mass (FFM), VO2max, daily EE and EE during sleep and seated activities were significantly higher in athletic than in non-athletic subjects of both sexes. VO2max, daily EE and EE during exercise adjusted for FFM were higher in athletic than in non-athletic adolescents (P < 0.001), whereas sleeping EE, BMR and EE during seated activities and adjusted for FFM were not significantly different between athletic and non-athletic adolescents. However, sex differences in EE remained significant. Thus, differences in EE between athletic and non-athletic adolescents resulted mainly from differences in FFM and physical exercise. Usual activity did not significantly affect energy utilization of substrates. Finally, individual relationships were computed between heart rate and EE with activity programmes simulating the usual activities of athletic and non-athletic adolescents with the goal of predicting EE of the same subjects in free-living conditions.

Fat partitioning and biochemical characteristics of fatty tissues in relation to plasma metabolites and hormones in normal and double-muscled young growing bulls

Plasma metabolites and hormones, and the biochemical characteristics of four fatty tissues (FT) were studied in two groups of six normal (N) or six double-muscled (DM) Belgian Blue young growing bulls fed the same net energy amount at the same live weight and slaughtered at 10 months of age. Average daily gain and feed efficiency did not significantly differ between the two groups. However, the DM bulls exhibited a higher proportion of muscles (+22%, P < 0.01) and a reduced proportion of fat (-49%, P < 0.01) mainly in the subcutaneous FT (-80%, P < 0.05). Triiodothyronine, insulin and glucose plasma concentrations tended to be lower in DM bulls (-24%, P < 0.02; -27%, P = 0.14; -7%, P = 0.06, respectively) and were positively related to the higher fat development in N bulls. From the results of total protein. DNA, lipid and TG contents of FT, it appeared that a reduction in fat storage per fat cell (hypotrophy) or a reduction in total fat cell number (hypoplasia) could explain, in DM bulls, two-thirds and one-third of the reduction of perirenal and subcutaneous FT weights, respectively, as compared to N bulls. In contrast, either hypotrophy or hypoplasia was the main cause of omental or intermuscular FT weight reduction in DM animals.

Critical evaluation of the factorial and heart-rate recording methods for the determination of energy expenditure of free-living elderly people

The aim of the present study was to validate against the doubly-labelled water (DLW) technique the factorial method and the heart rate (HR) recording method for determining daily energy expenditure (DEE) of elderly people in free-living conditions. The two methods were first calibrated and validated in twelve healthy subjects (six males and six females; 70.1 (SD 2.7) years) from open-circuit whole-body indirect calorimetry measurements during three consecutive days and during 1 d respectively. Mean energy costs of the various usual activities were determined for each subject using the factorial method, and individual relationships were set up between HR and energy expenditure for the HR recording method. In free-living conditions, DEE was determined over the same period of time by the DLW, the factorial and the HR recording methods during 17, 14 and 4 d respectively. Mean free-living DEE values for men estimated using the DLW, the factorial and the HR recording methods were 12.8 (SD 3.1), 12.7 (SD 2.2) and 13.5 (SD 2.7) MJ/d respectively. Mean free-living DEE values for women were 9.6 (SD 0.8), 8.8 (SD 1.2) and 10.2 (SD 1.5) MJ/d respectively. No significant differences were found between the three methods for either sex, using the Bland & Altman (1986) test. Mean differences in DEE of men were -0.9 (SD 11.8) % between the factorial and DLW methods, and + 4.7 (SD 16.1) % between the HR recording and DLW methods. Similarly, in women, mean differences were -7.7 (SD 12.7) % between the factorial and DLW methods, and + 5.9 (SD 8.8) % between the HR recording and DLW methods. It was concluded that the factorial and the HR recording methods are satisfactory alternatives to the DLW method when considering the mean DEE of a group of subjects. Furthermore, mean energy costs of activities calculated in the present study using the factorial method were shown to be suitable for determining free-living DEE of elderly people when the reference value (i.e. sleeping metabolic rate) is accurately measured.

Intraruminal propionate supplementation modifies hindlimb energy metabolism without changing the splanchnic release of glucose in growing lambs

The influence of propionate supplementation on the splanchnic metabolism of energy-yielding nutrients and the supply of glucose to the hindlimb was investigated in growing lambs. Six rumen-cannulated and multicatheterized lambs (32.2 kg), fed frozen rye grass at 690 kJ metabolizable energy intake/d per kg body weight0.75, were infused intraruminally with a salt solution (control) or with propionate solutions at 0.55 mol/d (P1) or 0.98 mol/d (P2) according to a replicated Latin square design. In the rumen fluid, supplementation decreased the acetate:propionate molar ratio from 2.36:1 to 1.37:1, without modifying the ruminal concentrations of acetate and NH4. As a result, the portal appearance of propionate increased by 51 and 72 % with P1 and P2, respectively, and that of l-lactate doubled. Across the liver, net extraction of propionate increased by 47 and 67 % with P1 and P2, respectively. However, the net hepatic production of glucose remained unchanged, probably as the result of a substantial rise in insulin secretion and its hepatic extraction. Overall, the net splanchnic release of acetate, glucose and butyrate was not modified while that of l-lactate increased. Despite this, the net uptake of acetate, glucose, l-lactate and non-esterified fatty acids by the hindlimb increased. Propionate probably enhanced the storage of energy-yielding nutrients in the hindlimb, despite their unchanged release by the splanchnic tissues and the unmodified insulinaemia. Regulatory mechanisms are not clear.

Weaning marginally affects glucose transporter (GLUT4) expression in calf muscles and adipose tissues

The nutritional regulation of glucose transporter GLUT4 was studied in eight muscles and four adipose tissues from two groups of preruminant (PR) or ruminant (R) calves of similar age (170 d), empty body weight (194 kg) at slaughter, and level of net energy intake from birth onwards. Isocitrate dehydrogenase (EC 1.1.1.41) activity in muscles was not different between PR and R except in masseter muscle from the cheek (+71% in R; P < 0.003), which becomes almost constantly active at weaning for food chewing. Basal and maximally-insulin-stimulated glucose transport rate (GTR) per g tissue wet weight in rectus abdominis muscle were significantly higher in R calves (+31 and 41% respectively; P < 0.05). GLUT4 protein contents did not differ in muscles from PR and R except in masseter (+74% in R; P < 0.05) indicating that the increased GTR in rectus abdominis cannot be accounted for by an enhanced GLUT4 expression. GLUT4 mRNA levels did not differ between the two groups of animals in all muscles suggesting a regulation of GLUT4 at the protein level in masseter. GLUT4 number expressed on a per cell basis was lower in adipose tissue from R calves (-39%; P < 0.05) and higher in internal than in peripheral adipose tissues. In summary, the regulation of GLUT4 in calves at weaning differs markedly from that previously described in rodents (for review, see Girard et al. 1992). Furthermore, significant inter-individual variations were shown for metabolic activities in muscle and for biochemical variables in adipose tissue.

Net energy value of two low-digestible carbohydrates, Lycasin HBC and the hydrogenated polysaccharide fraction of Lycasin HBC in healthy human subjects and their impact on nutrient digestive utilization.

The metabolizable energy content of low-digestible carbohydrates does not correspond with their true energy value. The aim of the present study was to determine the tolerance and effects of two polyols on digestion and energy expenditure in healthy men, as well as their digestible, metabolizable and net energy values. Nine healthy men were fed for 32 d periods a maintenance diet supplemented either with dextrose, Lycasin HBC (Roquette Frères, Lestrem, France), or the hydrogenated polysaccharide fraction of Lycasin HBC, at a level of 100 g DM/d in six equal doses per d according to a 3 x 3 Latin square design with three repetitions. After a 20 d progressive adaptation period, food intake was determined for 12d using the duplicate meal method and faeces and urine were collected for 10 d for further analyses. Subjects spent 36 h in one of two open-circuit whole-body calorimeters with measurements during the last 24h. Ingestion of the polyols did not cause severe digestive disorders, except excessive gas emission, and flatulence and gurgling in some subjects. The polyols induced significant increases in wet (+45 and +66% respectively, P<0.01) and dry (+53 and +75 % respectively, P<0.002) stool weight, resulting in a 2% decrease in dietary energy digestibility (P<0.001). They resulted also in significant increases in sleeping (+4.1%, P<0.03) and daily energy expenditure (+2.7 and +2.9% respectively, P<0.02) compared with dextrose ingestion. The apparent energy digestibility of the two polyols was 0.82 and 0.79 respectively, their metabolizable energy value averaged 14.1 kJ/g DM, and their net energy value averaged 10.8 kJ/g DM, that is, 35 % less than those of sucrose and starch.