T Nation

Warm Drinks Increase Insulin Response

A study carried out in Japan showed that in rats, the physiological responses to the ingestion of a glucose solution varied dramatically depending on the temperature of the solution. The study measured blood sugar, blood insulin and brown adipose tissue activity following the ingestion of a 1M glucose solution at either 4 degrees Celsius or 25 degrees Celsius (Fridge temperature and room temperature respectively).

The key results were as follows: Both groups exhibited similar blood sugar responses. However, the ‘warm’ group showed a rise in insulin 3 minutes after ingestion whereas the ‘cold’ group showed a corresponding rise after 15 minutes. Perhaps more importantly, the ‘warm’ group showed an increase in brown adipose tissue activity whereas the ‘cold’ group did not, which implies that the thermic effect of ingesting sugars is absent if the solution is cold.

Bottom line: warm drinks raise insulin faster than cold drinks. Ingesting sugars warm raises the metabolic rate, whereas ingesting them cold does not.

Link to the article on PubMed: http://www.ncbi.nlm.nih.gov/pubmed/18262576

Interesting. Isn’t brown fat fairly irrelevant in humans though?

Apparently, the quantity and activity levels of brown fat in adult humans had previously been underestimated. The stuff is there, and it is active. But aside from that, the adipose tissue activity in rats is used as an indicator of several related metabolic processes which are used to dissipate excess energy as heat.

Although the brown fat activity in humans is not analogous with that in rats, the overall metabolic response is believed to be analogous. Hopefully someone will do some human studies on this, which will give a better indication. Meanwhile, it appears likely that the human body will improperly process sugars if they are delivered cold, so it’s probably best to avoid refrigerated sugary stuff, and to warm up workout drinks during the winter, if possible.

Damn, my preworkout shakes taste so much better cold too. Oh well. Anything that helps.