Leptin and energy restriction induced adaptation in energy expenditure

BACKGROUND: Diet-induced weight loss is accompanied by adaptive thermogenesis, i.e. a disproportional reduction of resting energy expenditure (REE) a decrease in physical activity and increased movement economy. OBJECTIVE: To determine if energy restriction induced adaptive thermogenesis and adaptations in physical activity are related to changes in leptin concentrations. METHODS: Eighty-two healthy subjects (23 men, 59 women), mean +/- SD age 41 +/- 8 years and BMI 31.9 +/- 3.0 kg/m(2), followed a very low energy diet for 8 weeks with measurements before and after the diet. Leptin concentrations were determined from fasting blood plasma. Body composition was assessed with a three-compartment model based on body weight, total body water (deuterium dilution) and body volume (BodPod). REE was measured (REEm) with a ventilated hood and predicted (REEp) from measured body composition. Adaptive thermogenesis was calculated as REEm/REEp. Parameters for the amount of physical activity were total energy expenditure expressed as a multiple of REEm (PAL), activity-induced energy expenditure divided by body weight (AEE/kg) and activity counts measured by a tri-axial accelerometer. Movement economy was calculated as AEE/kg (MJ/kg/d) divided by activity counts (Mcounts/d). RESULTS: Subjects lost on average 10.7 +/- 4.1% body weight (P<0.001). Leptin decreased from 26.9 +/- 14.3 before to 13.9 +/- 11.3 mug/l after the diet (P<0.001). REEm/REEp after the diet (0.963 +/- 0.08) was related to changes in leptin levels (R(2)=0.06; P<0.05). There was no significant correlation between changes in leptin concentrations and changes in amount of physical activity. Movement economy changed from 0.036 +/- 0.011 J/kg/count to 0.028 +/- 0.010 J/kg/count and was correlated to the changes in leptin concentrations (R(2)=0.07; P<0.05). CONCLUSION: During energy restriction, the decrease in leptin explains part of the variation in adaptive thermogenesis. Changes in leptin are not related to the amount of physical activity but could partly explain the increased movement economy

Genetic predisposition, dietary restraint and disinhibition in relation to short and long-term weight loss

BACKGROUND: Interindividual differences in response to weight loss and maintenance thereafter are ascribed to genetic predisposition and behavioral changes. OBJECTIVE: To examine whether body weight and short and long-term body weight loss were affected by candidate single nucleotide polymorphisms (SNPs) and changes in eating behavior or by an interaction between these genetic and behavioral factors. METHODS: 150 healthy subjects (39 males, 111 females) aged 20-50y with a BMI of 27-38kg/m2 followed a very low energy diet for 8-weeks, followed by a 3-month weight maintenance period. SNPs were selected from six candidate genes: ADRB2, FTO, MC4R, PPARG, PPARD, and PPARGC1A. Changes in eating behavior were determined with the Three Factor Eating Questionnaire. RESULTS: A high genetic predisposition score was associated with a high body weight at baseline and more short-term weight loss. From the six selected obesity-related SNPs, FTO was associated with increased body weight at baseline, and the effect allele of PPARGC1A was positively associated with short-term weight loss, when assessed for each SNP separately. Long-term weight loss was associated with a larger increase in dietary restraint and larger decrease in disinhibition. CONCLUSION: During long-term weight loss, genetic effects are dominated by changes in eating behavior

Concomitant changes in sleep duration and body weight and body composition during weight loss and 3-mo weight maintenance

BACKGROUND: An inverse relation between sleep duration and body mass index (BMI) has been shown. OBJECTIVE: We assessed the relation between changes in sleep duration and changes in body weight and body composition during weight loss. DESIGN: A total of 98 healthy subjects (25 men), aged 20-50 y and with BMI (in kg/m2) from 28 to 35, followed a 2-mo very-low-energy diet that was followed by a 10-mo period of weight maintenance. Body weight, body composition (measured by using deuterium dilution and air-displacement plethysmography), eating behavior (measured by using a 3-factor eating questionnaire), physical activity (measured by using the validated Baecke's questionnaire), and sleep (estimate by using a questionnaire with the Epworth Sleepiness Scale) were assessed before and immediately after weight loss and 3- and 10-mo follow-ups. RESULTS: The average weight loss was 10% after 2 mo of dieting and 9% and 6% after 3- and 10-mo follow-ups, respectively. Daytime sleepiness and time to fall asleep decreased during weight loss. Short (7 to /=9 h) did not change significantly during weight loss. This change in sleep duration was concomitantly negatively correlated with the change in BMI during weight loss and after the 3-mo follow-up and with the change in fat mass after the 3-mo follow-up. CONCLUSIONS: Sleep duration benefits from weight loss or vice versa. Successful weight loss, loss of body fat, and 3-mo weight maintenance in short and average sleepers are underscored by an increase in sleep duration or vice versa. This trial was registered at clinicaltrials.gov as NCT01015508

The Potential of Increased Meat Intake to Improve Iron Nutrition in Rural Kenyan Schoolchildren

Schoolchildren in developing countries often have inadequate intakes of iron, due primarily to poor I bioavailability. Increasing meat in the diet could improve both the amount of iron consumed and its availability. The effect of increases in intakes of meat and ascorbic acid on absorbed iron was investigated by theoretically modifying the habitual diet of rural Kenyan schoolchildren. The projected changes in the amount of absorbed iron and prevalence of inadequate iron intakes were calculated for 78 children (6-9 years of age). The prevalence of inadequate iron intakes decreased from 77% to 54% through the theoretical addition of 50 g beef prevalence or 100 mg ascorbic acid and to 23% through the addition of both to dinner each day. To reduce the of inadequate iron intake to 5%, the addition of 100 g meat plus 150 mg ascorbic acid would be necessary. The combined addition of meat and ascorbic acid to a meal has the potential to reduce the,projected prevalence of inadequate iron intakes among these schoolchildren

Sleep duration, sleep quality and body weight: parallel developments

The increase in obesity, including childhood obesity, has developed over the same time period as the progressive decrease in self-reported sleep duration. Since epidemiological studies showed an inverse relationship between short or disturbed sleep and obesity, the question arose, how sleep duration and sleep quality are associated with the development of obesity. In this review, the current literature on these topics has been evaluated. During puberty, changes in body mass index (BMI) are inversely correlated to changes in sleep duration. During adulthood, this relationship remains and at the same time unfavorable metabolic and neuro-endocrinological changes develop, that promote a positive energy balance, coinciding with sleep disturbance. Furthermore, during excessive weight loss BMI and fat mass decrease, in parallel, and related with an increase in sleep duration. In order to shed light on the association between sleep duration, sleep quality and obesity, until now it only has been shown that diet-induced body-weight loss and successive body-weight maintenance contribute to sleep improvement. It remains to be demonstrated whether body-weight management and body composition improve during an intervention concomitantly with spontaneous sleep improvement compared with the same intervention without spontaneous sleep improvement

A homozygous mutation in the luteinizing hormone receptor causes partial Leydig cell hypoplasia: correlation between receptor activity and phenotype

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