Circulating Insulin Concentrations, Smoking, and Alcohol Intake Are Important Independent Predictors of Leptin in Young Healthy Men

Abstract

MANTZOROS, CHRISTOS S., ANTONIOS D. LIOLIOS, NICHOLAS A. TRITOS, VIRGINIA G. KAKLAMANI, DIMITRIOS E. DOULGERAKIS, IOANNIS GRIVEAS, ALAN C. MOSES, JEFFREY S. FLIER. Circulating insulinconcentrations, smoking, and alcohol intake are important independent predictors of leptin in young healthy men. Obes Res. 1998;6:179-186. Objective: Leptin, an adipocyte-secreted hormone, has been shown to signal the status of energy stores to the brain, regulate energy homeostasis, and mediate the neuroendocrine response to food deprivation. Obesity is associated with increased leptin levels, and several hormones, including insulin and glucocorticoids, have been associated with leptin levels and expression in rodents. Although obesity has been strongly associated with increased leptin in humans, a significant percentage of leptin's variability remains unexplained. The role of endogenous hormones, demographic factors, or certain life-style factors in explaining the residual variability of leptin levels has not yet been clarified. We performed this cross-sectional study to document the relative importance of obesity, lifestyle factor, and endogenous hormones in determining serum leptin levels. Research Methods and Procedures:We measured serum concentrations of insulin, cortisol, testosterone, growth hormone, and dehydroepiandrosterone sulfate; ascertained anthropometric, demographic, and lifestyle characteristics; and studied these variables in relationship to serum leptin concentrations in a sample of young healthy men.Results: Obesity and alcohol intake were independently and positively associated with circulating leptin concentrations. Additionally, cigarette smoking was negatively and independently associated with leptin concentrations. Finally, serum insulin concentration was an independent hormonal determinant of circulating leptin concentrations, whereas serum testosterone was negatively associated with leptin only by bivariate analysis.Discussion: We conclude that, in addition to obesity, cigarette smoking, alcohol intake, and serum insulin levels are associated with leptin levels in a population of healthy young men.

Association of Circulating Levels of Leptin and Adiponectin With Metabolic Syndrome and Coronary Heart Disease in Patients With Various Coronary Risk Factors

“…Lower leptin levels were also observed, consistent with previously reported findings, 16) although conflicting results have been reported. Leptin is a 26-kDa protein secreted primarily from adipocytes, and suppresses food intake and increases energy expenditure by enhancing thermogenesis and increasing the metabolic rate in humans.…”

Dietary and lifestyle factors in relation to plasma leptin concentrations among normal weight and overweight men

“…52,53 Some studies have shown that higher alcohol consumption is associated with total energy intake 54 and favors fat storage and weight gain, 55 which may increase adipocyte Dietary and lifestyle factors and plasma leptin levels N-F Chu et al mRNA expression of leptin. 36 Our results do not indicate an association between alcohol intake and plasma leptin concentrations overall or in either normal weight or overweight men. Alcohol intake does not seem to be a major modulator of energy intake and leptin production.…”

“…52,53 Furthermore, smoking may be associated with an increase in leptin sensitivity. 35,36 The higher leptin concentrations among past smokers could be a marker of loss of leptin sensitivity. This could explain, in part, the usual weight gain that accompanies smoking cessation.…”

“…Interestingly, several previous studies have found an inverse association between cigarette smoking and plasma leptin, indicating that current smokers have lower leptin concentrations than non-smokers. 35,36 Whether this association is independent of diet and exercise is not known.…”

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

“…However, it has also been argued that this relationship was not clear evidence of resistance to leptin but rather an adaptative attempt to oppose other forces promoting obesity (Arch et al, 1998). Excess leptin may provide indirect information about behavioral aspects related to adiposity gain, such as a lack of physical activity, overfeeding (Kolaczynski et al, 1996) or alcohol consumption (Mantzoros et al, 1998). Our results show a negative association between plasma leptin and physical activity.…”