The relationship between leptin, gonadotropic hormones, and body composition during puberty in a Dutch children cohort.

OBJECTIVE: To investigate the relationship between leptin concentrations, gonadotropic hormone concentrations, and body composition during puberty in a Dutch children cohort. DESIGN: In a cohort of 98 children, we determined anthropometric measurements, body composition, and concentrations of leptin, FSH, and LH. RESULTS: Sex differences were observed from Tanner stage 1 onwards in weight, body fat percentage, and leptin/fat mass ratio. In boys and girls, the relationship between leptin concentrations and FM was weaker at Tanner stage 2 (R(2)=0.33 and R(2)=0.39; P<0.001), 3 (R(2)=0.27 and R(2)=0.36; P<0.002), and 4 (R(2)=0.21 and R(2)=0.28; P<0.03) than at Tanner stage 1 (R(2)=0.51 and R(2)=0.67; P<0.001) and 5 (R(2)=0.46 and R(2)=0.78; P<0.01). In girls, a peak in leptin concentrations (8.5+/-6.0 ng/ml) preceded a peak in LH and FSH concentrations (15.1+/-3.5 and 5.0+/-4.5 IU/l). A lead/lag relationship was observed of leptin at Tanner stage 1 to LH and FSH at Tanner stage 2 (R(2)=0.12, P<0.05 and R(2)=0.18, P<0.05). In boys, there was no peak in leptin, LH, and FSH; additionally, leptin at Tanner stage 3 was related FSH at Tanner stage 4 (R(2)=0.17, P<0.04). CONCLUSION: In boys and girls during puberty, factors independent of fat mass become (transiently) more important in the regulation of plasma leptin concentrations. Moreover, in girls, leptin is suggested to act as a permissive factor for the onset of puberty, while, in boys, leptin has a different timing and possibly different function.

Leptin-adiposity relationship changes, plus behavioral and parental factors, are involved in the development of body weight in a Dutch children cohort.

BACKGROUND: The development of body weight is determined by different factors, namely genetic, behavioral, parental and physiological. OBJECTIVE: To investigate whether genetic, behavioral, parental and physiological factors are involved and the extent of involvement in the development of body weight at ages 12 and 13 y in a Dutch children cohort. METHODS: In a Dutch cohort of 94 children at ages 12 and 13 y, we determined anthropometric measurements, body composition, leptin concentrations, TFEQ scores, physical activity, as well as 3 polymorphisms, and in the parents we determined anthropometric measurements and TFEQ scores. RESULTS: 11% of the children in the cohort were classified as overweight. The genotype frequency distributions of the PPARy2, GRL and CNTF genes at ages 12 and 13 y were not significantly different for the overweight children compared to the lean children. Overweight children showed higher dietary restraint and disinhibition scores. Overweight children's parents had a higher BMI, dietary restraint and disinhibition scores, compared to lean children's parents. A peak in leptin concentrations between 7 and 13 y was shown at 12 y. In lean boys, the decrease in leptin concentrations between 12 and 13 y was related to an increase in fat free mass. At the age of 12 y predominantly the physiological factors were predictors for body weight, and at the age of 13 y both the physiological and behavioral factors were predictors for body weight. CONCLUSION: We conclude from this longitudinal study, that leptin appeared to play an important role in the development of body weight during puberty, in addition to behavioral and parental factors.

Daily physical activity counts vs structured activity counts in lean and overweight Dutch children.

The objectives of this study were to compare daily physical activities, and activities performed according to a structured protocol, measured with tri-axial accelerometers (Tracmor-4), between lean and overweight children. Fourteen overweight children (59.8+/-9.5 kg) and fifteen lean matched controls (47.2+/-8.7 kg) wore the Tracmor-4 daily, during 12+/-1.3 h, for one week in their home environment. Of these, 24 children participated in a sports afternoon, where they performed activities according to the same structured protocol. In addition, physical activity was estimated using a modified Baecke questionnaire. Body composition was determined. Total mean Tracmor counts/day were significantly lower for the overweight children than for the lean (overweight: 46.1+/-6.9 vs. lean: 54.4+/-11.2 kCounts/day, p=0.02), while reported activities (Baecke score) were similar. When performing activities according to the structured protocol, there was no difference in mean Tracmor counts between the two groups (overweight: 36.3+/-6.9 vs. lean: 34.7+/-6.6 kCounts, p=0.6). Daily physical activities were inversely related to percentage body fat (r(2)=0.29, p<0.01); structured activities were not. As compared to lean children, overweight children moved less without being aware of it; yet exerted the same movements per activity. We conclude that in overweight children daily physical activities were reduced and structured activities performed according to instructions were not. In order to prevent progressive overweight or obesity, overweight children should take part in as many as possible structured and scheduled sports activities throughout the week, and be encouraged to behave physically active in daily life.

Metabolic effects of green tea and of phases of weight loss.

The effect of ingestion of green tea (GT) extract along with a low-energy diet (LED) on health-related blood parameters, and the relationships among changes in metabolic parameters and phases of weight loss were assessed. A double-blind, placebo-controlled, parallel design was used. 46 female subjects (BMI 27.7+/-1.8 kg/m(2)) were fed in energy balance from days 1 to 3, followed by a LED with GT (n=23) or placebo (PLAC, n=23) from days 4 to 87. The LED-period consisted of a phase 1 of 4 weeks (days 4-32) followed by a phase 2 of 8 weeks (days 32-87). Body composition and fasting blood samples were determined on days 4, 32 and 87. No significant differences were observed between the blood parameters of the PLAC and GT group. In phase 1 compared to phase 2 the rate of weight loss was 0.09+/-0.05 kg/day vs. 0.03+/-0.03 kg/day (p<0.001); Fat free mass (FFM) was 21% of weight loss in phase 1 vs. 7% in phase 2 (ns). Surprisingly, favourable changes in free fatty acids, triacylglycerol, beta-hydroxybutyrate, glucose and total cholesterol in phase 1 were reversed in phase 2 (p<0.01). Taken together, GT supplementation during a LED had no effect on health-related blood parameters. Initial improvements in several blood measures at day 32 were reversed by day 87, despite continued weight loss. Modest weight loss improved HDL cholesterol and blood pressure.

Categorical strategies based on subject characteristics of dietary restraint and physical activity, for weight maintenance.

OBJECTIVE: The aim of this study was to investigate the effect of categorical strategies based on subject-specific characteristics of dietary restraint and physical activity, on weight maintenance (WM) in overweight and obese subjects, after a very low calorie diet (VLCD). Furthermore, find predictors of WM that can be important in the context of obesity treatment. METHODS: In all, 120 subjects (age: 49.0+/-9.8 y, BMI 31.0+/-3.8 kg/m(2)) followed a VLCD (2.1 MJ/day) for 6 weeks in a free-living situation, followed by a period of 1 y WM. Body weight (BW), body composition, leptin concentration, dietary restraint and physical activity were determined right before (t0) and after (t1) the VLCD, after 3 months (t2) and after 1 y (t3). During WM, subjects were divided into four categories of WM guidelines (dietary, activity, diet+activity, placebo), taking their capability measured during weight loss and their preference for particular guidelines into account. RESULTS: BW loss during VLCD was 7.0+/-3.1 kg. After 1 y follow-up, BW regain was 56.3+/-55.0%, without significant differences between the four groups. With respect to measured capability during weight loss, subjects with an increased dietary restraint (F1 of the Three Factor Eating Questionnaire) had less BW regain than subjects with an increased physical activity (Baecke questionnaire) (35.5+/-53.2 vs 68.5+/-46.4%, P<0.05). Moreover, activity guidelines promoted WM in dietary disciplined subjects compared to activity-related disciplined subjects (% regain: 25.2 vs 74.3%, P<0.05). Subjects receiving guidelines that were opposite to their preference showed a better WM than subjects receiving preferred guidelines. After 1 y WM, 21 subjects were successful (<10% BW regain) and 99 unsuccessful (> or =10% BW regain). At baseline, these groups were significantly different in BMI (resp. 32.7+/-4.9 vs 30.7+/-3.5 kg/m(2), P<0.05), waist circumference (106.5+/-14.0 vs 100.6+/-11.2 cm, P<0.05) and fat mass (FM) (35.2+/-10.6 vs 32.1+/-6.6%, P=0.06). Finally, successful subjects appeared to spare fat-free mass (FFM) to a greater extent than unsuccessful subjects. CONCLUSION: After weight loss, type of guidelines (dietary, activity, placebo) is not related to the magnitude of WM, whereas guidelines opposite to the subject's capability and preference are related. These only reach successful WM (>90%) in originally dietary disciplined subjects who are supported by characteristics such as a relatively high baseline BMI, waist circumference and FM, together with the ability to spare FFM.

Estimating changes in daily physical activity levels over time: implication for health interventions from a novel approach.

The aim of this study was to use a novel method to examine and compare physical activity levels in four different groups of men to investigate the impact of modernity on activity levels. Physical activity levels of four different groups of men were measured and compared, using a tri-axial accelerometer (Tracmor). The first group (HA = historically active) were actors in a historical theme park who play the part of Australian settlers 150 years ago, the second were sedentary modern-day office workers (MS = modern sedentary), the third men who had successfully lost weight (SWL) in a modern men's weight loss program and the last, men who were unsuccessful (UWL) in the same program. Men who had successfully lost weight in a weight loss program were active at a level similar to that of men performing activity at a level carried out historically. Both of these groups were in turn significantly more active than modern-day sedentary workers (p < 0.05) and men who had not been successful at losing weight (p < 0.01). A linear regression between weekly average activity levels and the degree of waist size loss showed a significant positive association (r = 0.52, p < 0.01). The data suggest that a higher activity level facilitates the maintenance of long-term weight loss and this level is likely to approximate activity levels in the past. For the prevention and treatment of obesity an increase in physical activity is necessary, because (long-term) weight loss or weight maintenance is unlikely to occur when people are as sedentary as most people are today.

The effect of grape-seed extract on 24 h energy intake in humans.

OBJECTIVE: Since grape-seed extract has been shown to stimulate lipolysis in vitro and reduce food intake in rats, we assessed the efficacy of grape-seed extract with respect to energy intake (EI) and satiety. DESIGN: In a randomized, placebo-controlled, double-blind, cross-over study, 51 subjects (age 18-65 y, body mass index 22-30 kg/m2) ate an ad libitum lunch and dinner twice in the University Restaurant for 3 days. Standard breakfasts and snacks were provided. Supplements were taken 30-60 min prior to each meal. RESULTS: In the total study population, no difference in 24 h EI was found between the grape-seed extract and placebo. However, in the subgroup of subjects (n=23) with an energy requirement > or =the median of 7.5 MJ/day, EI was reduced by 4% (DeltaEI 352.1 kJ/24 h, P=0.05) after grape-seed extract compared to placebo treatment. Meanwhile, there were no significant differences in macronutrient composition, attitude towards eating, satiety, mood or tolerance. CONCLUSIONS: Grape seed reduced 24 h EI, with on average 4% in subjects who had an energy requirement > or =7.5 MJ/day, without further effects on satiety, mood or tolerance. These findings suggest that grape seed could be effective in reducing 24 h EI in normal to overweight dietary unrestrained subjects, and could, therefore, play a significant role in body-weight management.

Estimating historical changes in physical activity levels.

OBJECTIVE: To compare activity levels between a simulated "historical" lifestyle and a "modern" lifestyle to try to validate earlier estimates of secular changes in activity. DESIGN: Triaxial accelerometers (TRACMORs) were used to measure activity levels in a "historical" group of seven male actors who were paid to live like early Australian settlers at a theme park north of Sydney (eg, minimising the use of modern technology) for a week. Results were compared with those from a group of seven "modern" sedentary office workers. RESULTS: Activity levels were up to 2.3 times greater in the historical group than the modern group. Calculations based on body weight and energy expenditure suggest the difference is the equivalent of walking up to 16 km per day more in the past than today. CONCLUSIONS: These findings accord with two previous estimates of changes in daily activity levels over time and suggest that recent public health guidelines for increasing physical activity may be inadequate.