I find myself defending him here more than I probably need to, but I've gotta say that time and time again as I wade through the scientific literature I find sources and explanations for many of his assertions....
I've posted a lengthy list of references about leptin and thermogenesis on here, today I've come across this paper that includes a section about cold temps. I'm not saying this paragraph answers everything, but in response to people who say his blogs spout unbacked claims, there are at least solid connections to be made between leptin and cold temps.
It has been shown that cold exposure
reduces circulating leptin levels and
leptin expression,19,28,70 – 72
suggesting that leptin may participate
in the adaptive mechanism triggered by
variations in external temperature.
Trayhurn and co-workers28,73
hypothesized that the inhibitory
effect of low temperature on leptin
results from an increase in the
adrenergic tone induced by exposure to
cold temperatures,which would in turn
act through the b3-adrenoceptor
(b3-AR) present in adipose tissue,
inducing a reduction in the expression
of leptin mRNA. It has been reported
that this was the case for mice19 and
rats.28 Hardie et al70 also found that
acute cold exposure decreased the
level of circulating leptin in lean
Zucker rats. However, it appears that
this is not so for other rodents, such
as the Djungarian hamster.21 For
animals living in areas with large
seasonal temperature variations, a
decrease in serum leptin may represent
an adaptive mechanism for maximising
the size of fat deposits when
environment temperature is low.
Trayhurn et al28 showed that the
leptin mRNA observed in brown adipose
tissue was further reduced on cold
exposure, paralleling the response
observed in mouse white adipose
tissue. These authors postulated that
these findings may suggest the
existence of a feedback loop between
the hypothalamus and BAT, that would
result in an inhibition of leptin gene
expression when the sympathetic system
is activated. Interestingly,
Trayhurn et al28 reported contrasting
results to those reported by Moinat et
al,19 who showed no change in leptin
expression in the white adipose tissue
of rats which were acutely
19 Moinat M, Deng C, Muzzin P, Assimocopoulos-Jeannet F, Seydoux, J, Dulloo AG, Giacobino JP. Modulation of obese gene expression in rat brown and white adipose tissues. FEBS Lett 1995; 373: 131 – 134.
28 Trayhurn P, Duncan JS, Rayner DV. Acute cold-induced suppres- sion of ob (obese) gene expression in white adipose tissue of mice; mediation by the sympathetic system. Biochem J 1995; 311: 729 – 733.
70 Hardie LJ, Rayner DV, Holmes S, Trayhurn P. Circulating leptin levels are modulated by fasting, cold exposure and insulin administration in lean but Zucker (fa=fa) rats as measured by ELISA. Biochem Biophys Res Commun 1996; 223: 660 – 665.
71 MacDougald OA, Hwang CS, Fan H, Lane MD. Regulated expres- sion of the obese gene product (leptin) in white adipose tissue and 3T3-L1 adipocytes. Proc Natl Acad Sci USA 1995; 92: 9034 – 9037.
72 Peino R, Pineiro V, Gualillo O, Menendez C, Brenlla J, Casabiell X, Dieguez C, Casanueva FF. Cold exposure inhibits leptin secretion in vitro by a direct and non-specific action on adipose tissue. Eur J Endocrinol 2000; 142: 195 – 199.