The "Obesity Epidemic in Children" and the
World
Testosterone
reduces leptin. Leptin reduces appetite. Therefore, children
of
higher testosterone have less appetite suppression. It is my
hypothesis that the percentage of individuals of higher
testosterone is
increasing. Therefore, overeating is increasing. This
may
account for the obesity "epidemic" in the U.S.
(Additionally,
testosterone stimulates
ghrelin
which
stimulates appetite; see second citation, below.) (Copyright
2003, James Michael Howard, Fayetteville, Arkansas, U.S.A.)
"Relation of race, age, and sex hormone differences
to serum leptin concentrations in children and adolescents.
We
explored the effects of race, age, and sex hormones on the serum
leptin
concentrations in 203 white and 88 black children and
adolescents (ages
9.3-20.5 years). A significant sex by race interaction on serum
leptin
levels (p = 0.0301) was observed with lower serum leptin
concentrations, adjusted for subscapular thickness and age, in
black
boys than in white boys. Girls had serum leptin levels that were
on
average 2.15 times those of boys (p < 0.0001). There was an
age by
sex interaction (p < 0.0001) with serum leptin concentrations
decreasing in boys but not in girls with age. A strongly inverse
relationship of serum testosterone levels with serum leptin
levels in
boys (p = 0.0067) appeared to explain this effect of age. In
conclusion, the serum leptin concentration is slightly lower in
black
boys. A higher
testosterone
level in boys appears to account for an age-related decline in
serum
leptin in boys and the overall lower levels in boys than in
girls." (Horm Res. 1998;49(5):240-6)
"Testosterone replacement therapy restores normal ghrelin in
hypogonadal men.
We
recently described a connection between androgens and ghrelin in
women
affected by the polycystic ovary syndrome. To further
investigate the
interaction between sex steroids and ghrelin, we investigated
circulating ghrelin levels in a group of hypogonadal men before
and
after therapeutic intervention aiming at normalization low
testosterone
(T) concentrations. Seven hypogonadal men were compared with
nine
overweight/moderately obese men matched for body mass index and
body
fat distribution parameters, as well as with 10 normal weight
controls.
Total and free T and plasma ghrelin levels were significantly
lower in
the hypogonadal men than in the control groups. Hypogonadal men
also
had a significantly higher insulin resistance state. Ghrelin
levels
were positively correlated with both total and free T
concentrations. A
significant correlation was also found between ghrelin and the
anthropometric parameters and the insulin resistance indexes.
However,
in a multiple regression analysis in which a correction for all
covariants was performed, only the relationship with total and
free T
persisted. After the 6-month replacement T therapy, ghrelin
levels of
hypogonadal patients increased and did not differ significantly
in
comparison with both control groups. The positive correlation
between
ghrelin and androgens still persisted after T replacement
therapy,
after adjusting for confounding variables. These data further
indicate
that sex hormones modulate circulating ghrelin concentrations in
humans. This may be consistent with the concept that ghrelin may
exert
a relevant role in the endocrine network connecting the control
of the
reproductive system with the regulation of energy balance." (
Clin
Endocrinol Metab. 2003 Sep;88(9):4139-43)