Table 1.

Known Effects of the Circadian System on Metabolism in Humans.¹

	Diurnal Rhythm?	Circadian Rhythm?	Affected by Misalignment?
GLUCOSE METABOLISM
Glucose tolerance	Yes	Yes	Yes
Fasting glucose	Yes	Mixed	No
Postprandial glucose2	Yes	Yes	Yes
Fasting insulin	Mixed	No	No
Postprandial insulin2	Yes	Mixed	Yes
Beta-cell responsiveness	Yes	?	?
Insulin secretion	Yes	Yes	Yes
Insulin clearance	Yes	Yes	?
Peripheral insulin sensitivity	Yes	Yes	Yes
Adipoctye insulin sensitivity	Yes	Yes	?
Hepatic insulin sensitivity	Mixed	?	?
LIPID METABOLISM
Cholesterol synthesis rate	Yes	?	?
Total cholesterol	Yes	?	?
LDL cholesterol	Yes	?	?
HDL cholesterol	Mixed	?	?
Triglycerides	Yes	Yes	No
FFAs	Yes	No	Mixed
Plasma phospholipids	Yes	At least some	?
Plasma acylcarnitines	Some	?	?
Diglycerides	Yes	Yes	?
Mitochondrial lipid oxidation	Yes	?	?
ENERGY METABOLISM
Energy expenditure	Yes	Yes	Yes
Resting energy expenditure	No	No	No
TEF	Yes	Yes	No
Fasting RQ	No	No	Yes
Postprandial RQ	Mixed	Mixed	Yes
Subjective hunger	Yes	Yes	Yes
Food intake	Yes	No	?
Leptin	Yes	Mixed	Yes
Ghrelin	Yes	No	No

¹“?” means that the influence of the circadian system is unknown, whereas “Mixed” denotes that the data are conflicting.

²Data on the presence of circadian rhythms in glucose and insulin—as determined from CR protocols—are included under postprandial glucose and insulin.