Does relative leptinemia predict weight gain in humans?

Leptin production capacity determines food intake and susceptibility to obesity-induced diabetes in Oikawa-Nagao Diabetes-Prone and Diabetes-Resistant mice

AIMS/HYPOTHESIS

Obesity caused by overeating plays a pivotal role in the development of type 2 diabetes. However, it remains poorly understood how individual meal size differences are determined before the development of obesity. Here, we investigated the underlying mechanisms in determining spontaneous food intake in newly established Oikawa-Nagao Diabetes-Prone (ON-DP) and Diabetes-Resistant (ON-DR) mice.

METHODS

Food intake and metabolic phenotypes of ON-DP and ON-DR mice under high-fat-diet feeding were compared from 5 weeks to 10 weeks of age. Differences in leptin status at 5 weeks of age were assessed between the two mouse lines. Adipose tissue explant culture was also performed to evaluate leptin production capacity in vitro.

RESULTS

ON-DP mice showed spontaneous overfeeding compared with ON-DR mice. Excessive body weight gain and fat accumulation in ON-DP mice were completely suppressed to the levels seen in ON-DR mice by pair-feeding with ON-DR mice. Deterioration of glucose tolerance in ON-DP mice was also ameliorated under the pair-feeding conditions. While no differences were seen in body weight and adipose tissue mass when comparing the two mouse lines at 5 weeks of age, the ON-DP mice had lower plasma leptin concentrations and adipose tissue leptin gene expression levels. In accordance with peripheral leptin status, ON-DP mice displayed lower anorexigenic leptin signalling in the hypothalamic arcuate nucleus when compared with ON-DR mice without apparent leptin resistance. Explant culture studies revealed that ON-DP mice had lower leptin production capacity in adipose tissue. ON-DP mice also displayed higher DNA methylation levels in the leptin gene promoter region of adipocytes when compared with ON-DR mice.

CONCLUSIONS/INTERPRETATION

The results suggest that heritable lower leptin production capacity plays a critical role in overfeeding-induced obesity and subsequent deterioration of glucose tolerance in ON-DP mice. Leptin production capacity in adipocytes, especially before the development of obesity, may have diagnostic potential for predicting individual risk of obesity caused by overeating and future onset of type 2 diabetes. Graphical abstract.

Lower leptin levels are associated with higher risk of weight gain over 2 years in healthy young adults

Complete leptin deficiency is associated with weight gain and extreme obesity, according to studies of animals and of monogenic obesity in humans. It is still a matter of debate whether relative leptin deficiency plays a physiologic role in adiposity regulation in free-living humans. We hypothesized that leptin levels would be associated with subsequent weight changes in healthy normal-weight young adults. Our prospective cohort involved 150 healthy young adults (114 women and 36 men) followed over their years of study at the Université de Sherbrooke. Anthropometric measurements, fasting blood samples, 3-day food diaries, and a physical activity questionnaire were collected at baseline. Leptin levels were measured with radioimmunoassay. Associations between baseline leptin levels and subsequent anthropometric changes were assessed with multivariable linear regression models to account for adiposity at baseline, food intake, and energy expenditure. Over the 2-year follow-up, changes in body mass index (BMI) ranged from -0.8 to +2.6 kg·m(-2) in men (mean BMI change, +0.6 kg·m(-2)) and from -2.5 to +3.7 kg·m(-2) in women (mean BMI change, +0.1 kg·m(-2)). Lower leptin levels at baseline were associated with a higher risk of weight gain in women (r = -0.24; p = 0.01 for change in BMI) and in men (r = -0.27, p = 0.11), even after accounting for baseline BMI, total daily caloric intake, and energy expenditure (p = 0.02). In the subsample measured at 4 years (n = 63), baseline leptin levels were not associated with 4-year weight changes. Lower leptin levels are associated with a higher risk of weight gain over 2 years in healthy young adults.

Tracking of leptin, soluble leptin receptor, and the free leptin index during weight loss and regain in children

OBJECTIVE

To investigate changes in leptin and soluble leptin receptor (SLR) concentrations, and in the free leptin index (FLI) during weight loss and subsequent weight regain; and to ascertain whether these indices remain stable in the rank of the distribution in repeated measures (tracking) during perturbations of weight in obese children.

DESIGN AND MEASUREMENTS

In a longitudinal study, 115 obese children were examined during a 12- week weight loss programme and 28 months of follow-up. Height, weight, body composition, Tanner stages, testicular size, time of menarche, and concentrations of leptin and SLR were measured at baseline, on days 14, 33, and 82, and from months 10, 16, and 28.

RESULTS

During weight loss, leptin decreased and the SLR increased. During weight regain, leptin increased and the SLR decreased. The partial correlation coefficients expressing the relationship between leptin and SLR were significant in girls during both weight loss and weight regain, whereas in boys they were much weaker and not significant. Leptin, SLR and FLI exhibited individual-specific levels (tracking) during weight loss and regain in boys and girls. The observed tracking seemed stronger during weight loss than during weight regain. The observed tracking was independent of both baseline body mass index (BMI) standard deviation score (SDS) and pubertal development at baseline and of subsequent changes in BMI SDS and puberty stages.

CONCLUSION

Leptin and the SLR exhibit tracking during weight loss and regain, which indicates individual stability in the leptin system despite challenges of weight.

High plasma leptin predicts an increase in subcutaneous adiposity in children and adults

OBJECTIVE

To investigate the hypothesis that plasma leptin may predict adiposity changes.

DESIGN

A population-based cohort study.

SETTING

Fleurbaix and Laventie, in the north of France.

SUBJECTS

In all, 1175 subjects participated, of whom 946 completed measurements at baseline (1999) and follow-up (2001). After excluding 64 subjects obese at baseline, 882 subjects (478 adults, 404 children 8 years and over) were included in the analysis.

INTERVENTIONS

We measured plasma leptin concentrations at baseline and various adiposity parameters at baseline and follow-up. Partial correlation coefficients (r(p)) between baseline plasma leptin and each adiposity indicator at follow-up were calculated with adjustment for baseline age, pubertal stage, adiposity and familial correlations between siblings.

RESULTS

Changes in body mass index and percentage body fat were not related to baseline plasma leptin. High baseline plasma leptin predicted an increase (r(p) (P-value)) in the sum of the four skinfolds (0.18 (<0.0001)), the waist circumference (0.16 (0.0003)) and the waist-to-hip ratio (0.29 (<0.0001)) in adults only, and in the hip circumference in adults (0.20 (<0.0001)) and children (0.22 (<0.0001)). After adjustment for a set of four adiposity variables at baseline (percentage body fat, skinfolds, waist and hip circumferences), baseline plasma leptin predicted only changes in the sum of the four skinfolds in adults (0.15 (0.001)), with similar tendency although not significant in children (0.08 (0.13)).

CONCLUSIONS

A high leptin relative to baseline fat mass predicts fat mass gain over time, mainly in the subcutaneous location.

The genetics and pathophysiology of diabetes mellitus type II

Type II diabetes is a common, complex and heterogeneous group of disorders of growing public health concern. Paradoxically, rare monogenic forms of diabetes mellitus have been the most informative regarding diabetes pathophysiology to date. We discuss disappointing results of genetic approaches thus far, emphasizing the genetic heterogeneity underlying the common phenotypic endpoint of elevated blood glucose level and the phenotypic misclassification in large studies resulting from this admixture and from the obligatory use of epidemiological or clinical surrogate measures. We suggest that novel approaches that take explicit account of the phenotypic, environmental and genetic complexities of type II diabetes are needed and discuss some principles that might underlie such approaches.