A. Liuzzi et al., Serum leptin concentration in moderate and severe obesity: relationship with clinical, anthropometric and metabolic factors, INT J OBES, 23(10), 1999, pp. 1066-1073
OBJECTIVE: To study clinical, anthropometric and metabolic determinants of
serum leptin concentrations in a series of patients with a wide range of ob
esity.
SUBJECTS: 400 patients, 116 males and 284 females, aged 44 +/- 12.3 years w
ith body mass index (BMI) ranging from 31 to 82 kg/m(2) (mean 41.4 +/- 7.1)
,
MEASUREMENTS: Energy intake by 7-day recall, resting energy expenditure (RE
E) by indirect calorimetry, body composition determined by bioelectrical im
pedance; C index, an anthropometric index of abdominal fat distribution, an
d waist-hip ratio (WHR), blood glucose serum leptin concentrations, total c
holesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, uric
acid, and insulin concentrations HOMA IRI (homeostastis model assessment o
f insulin resistance index).
RESULTS: Leptin concentrations were higher in obese than in normal subjects
and in females than in males without differences between diabetic and non-
diabetic patients; leptin concentrations were not related to age and showed
a strong negative association with energy intake only in the group of wome
n with BMI less than 40. Leptin concentrations showed a direct correlation
with BMI and body fat values (expressed either as percentage of total body
mass or absolute fat mass) independent of age and sex. After adjustment for
fat mass, leptin values higher than predicted were found in women whereas
concentrations lower than predicted were found predominantly in men. Leptin
showed an inverse correlation with WHR and C-index, the latter persisting
also after correction for gender and fat mass. REE, but not REE/kg fat-free
mass (FFM) was inversely related to leptin also after correction for sex a
nd absolute fat mass. Leptin concentrations were directly associated with H
OMA IRI, insulin and HDL cholesterol and inversely associated with triglyce
rides and uric acid. The relationship of leptin with HOMA IRI was still evi
dent after adjusting for sex but was lost when absolute fat mass was added
to the model; HDL cholesterol and triglycerides appeared to be variables in
dependent of leptin concentrations even when both sex and fat mass were add
ed to the model.
CONCLUSIONS: In a large group of obese patients (half of whom had severe ob
esity, gender, BMI and fat mass accounted for the largest proportion of ser
um leptin concentrations variability. We found that in obese subjects there
is an effect of fat distribution on leptin concentrations and that, after
excluding variability due to absolute fat mass, patients with a greater amo
unt of abdominal fat have relatively low leptin concentrations which in tur
n relates to a metabolic profile compatible with an increased cardiovascula
r risk. Women with milder obesity may retain some degree of control of food
intake by leptin.