Study indicating link between low muscle glycogen and low body temperature

[hailtotheking]

Might explain why some of us who do IF, and / or dieting are feeling a bit nippy ...

Muscle glycogen availability and temperature regul... [J Appl Physiol. 1989] - PubMed result

Quote

J Appl Physiol. 1989 Jan;66(1):72-8.

Muscle glycogen availability and temperature regulation in humans.
Martineau L, Jacobs I.

Defence and Civil Institute of Environmental Medicine, Downsview, Ontario, Canada.

Abstract
The effects of intramuscular glycogen availability on human temperature regulation were studied in eight seminude subjects immersed in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each subject was immersed three times over a 3-wk period. Each immersion followed 2.5 days of a specific dietary and/or exercise regimen designed to elicit low (L), normal (N), or high (H) glycogen levels in large skeletal muscle groups. Muscle glycogen concentration was determined in biopsies taken from the vastus lateralis muscle before and after each immersion. Intramuscular glycogen concentration before the immersion was significantly different among the L, N, and H trials (P less than 0.01), averaging 247 +/- 15, 406 +/- 23, and 548 +/- 42 (SE) mmol glucose units.kg dry muscle-1, respectively. The calculated metabolic heat production during the first 30 min of immersion was significantly lower during L compared with N or H (P less than 0.05). The rate at which Tre decreased was more rapid during the L immersion than either N or H (P less than 0.05), and the time during the immersion at which Tre first began to decrease also appeared sooner during L than N or H. The results suggest that low skeletal muscle glycogen levels are associated with more rapid body cooling during water immersion in humans. Higher than normal muscle glycogen levels, however, do not increase cold tolerance.

PMID: 2917958 [PubMed - indexed for MEDLINE]

[Loki]

That makes sense as I know that those who go on ketogenic diets show a slight drop in average body temperature... this possibly explains why.

[hailtotheking]

Theres alot of nonsence out there about low body temp meaning your thyroid is shutting down, etc. but i think if you are dieting this is much more likely to be the reason. It was actually Martin Berkhan who first highlighted this study a while back because he kept getting asked about the cold feeling some people get initially when doing IF

[James]

I was thinking as much, many times I have been sure that low carb feeding (when glycogen dependent) creates low body temperature, experienced it BAD today after having a very low carb intake yesterday.