Why it’s OK to overindulge at Xmas
I posted this study last year Christmas over-eating does not result in excess fat deposition in humansClaus S, Helpers SL, Reindeer RTRNLapland Journal of EndocrinologyDec 2002, Vol 2002 (12): p1-3
The consumption of excess calories leading to the synthesis of adipose tissue is well documented and evidence-based. However, it has long been wondered why humans can over-indulge, especially on high fat foods, high sugar foods and alcohol, during the Yuletide period without any significant weight gain (p<0.001). There have been numerous studies to try to find the reasoning for this, especially due to reports of reduce physical activity at this time of year.
Recently the authors have discovered the substance nutrition santasic acid
which, when present in high amounts in adipocytes inhibits the enzyme acetyl CoA carboxylase, one of the rate limiting enzymes in the synthesis of fatty acids. The presence of santasic acid combined with the inactivity of acetyl CoA carboxylase also results in the immediate oxidation of macronutrients into energy, or if there is no immediate demand for energy the dissipation of the oxidative metabolites as heat through the skin (this may also in part explain why we rarely feel cold at Christmas time).
Foods which have especially high levels of santasic acid include Christmas pudding, mince pies, sherry trifle, Christmas cake and brandy butter. Turkey has been shown to contain high levels of another substrate xmatic acid
. The structure of xmatic acid is one carboxyl group less than santasic acid, which can be readily converted to santasic by the addition of a carboxyl group via the addition of heat. The authors note that cranberry sauce, turkey gravy, sausages and bacon contain substrates which have a free carboxyl group which is readily lost though heating and available for transfer to xmatic acid to form santasic acid.
It has also been observed that brussel sprouts contain an enzyme called alcohol fermatase
. This enzyme readily oxidises alcohol into a non-calorific form and inhibits the liver enzyme alcohol dehydrogenase. This theory may help to explain why the large consumption of alcohol of the Christmas period does not result in additional adipose formation.
To reinforce the findings the authors took blood samples from 6 healthy volunteers of varied BMIs. Baseline weights were taken 2 weeks before Christmas and the subjects were followed up on December 25th
and again on January 5th
. Serum levels of santasic acid and xmatic acid levels peaked on December 25th
and remained relatively high on January 5th
. Subjects were asked to complete food diaries for the duration of the study and no significant weight gain was noted in any of the subjects. It was also observed that blood levels of the enzyme alcohol fermatase were high in all but one subject (this subject had no mention of brussel sprouts on his food diary, however consumed very little alcohol).
The authors conclude that the high levels of the substrates santasic acid and xmatic acid and the enzyme alcohol fermatase in traditional festive cuisine provide a satisfactory explanation as to the observations why humans gain little excess adipose tissue over Christmas. To further reinforce the validity of the findings more research into the effects of the above substrates and enzymes is required and they may also hold possible answers for future treatments for obesity.
Their findings also collaborate with those of Bunny E, et al 2002 who examined high chocolate consumption over Easter and its subsequent effects on body weight.