Circadian Clocks, Food Intake, and Metabolism - Progress in Molecular Biology and Translational Science - page 125

With respect to diet-induced obesity, the daily period during which high
fat is consumed seems important for its obesogenic effects in rodents, as
shown by the lack of major adverse metabolic consequences of high-fat
feeding when it is restricted to the usual feeding period (nighttime for
mice). 173,174 Furthermore, fatty acid composition matters in the altered eat-
ing pattern induced by high-fat feeding. In rats, this effect is specifically
mediated by saturated fatty acids. 175
Finally, in animal studies, the adverse effects of desynchronization can be
alleviated by timed feeding. The increased gain in body mass of rats
desynchronized by a biweekly shift of the light-dark cycle is not observed
if food access is limited to the dark period (including during the shifted
cycle). 130 Feeding restricted to the dark period in rats (i.e., corresponding
to the usual period of food intake) limits body mass gain and
desynchronization resulting from forced activity imposed during the resting
period (daytime). 176
4.3. Light and other (de)synchronizers
For applying reliable chronotherapy in humans, it is important to deter-
mine internal time for each subject. A recent study reveals that two blood
samples taken at 12 h apart from each other are sufficient to estimate indi-
vidual circadian timing. 177 Adequate timing of light exposure can promote
phase adjustment of the master clock. In addition, timed light avoidance
can be as useful by preventing photic resetting and allowing transiently
endogenous free run. In view of the rather unique and exclusive synchro-
nizing role of light for the suprachiasmatic clock, a means to prevent
desynchronization implies strong and appropriate (timed), rather than
weak and mismatched lighting information (e.g., light at night). 178 As dis-
cussed by these authors, light strategy should combine also appropriate
timing of other putative (de)synchronizers (mealtime, exercise) in a global
“Zeitgeber hygiene.”
In humans also, timed carbohydrate-rich meals can act as a synchronizer
of peripheral oscillators. 179 Apart from meal timing, dietary energy density
during daytime may modulate overall energy intake. This observation led,
for instance, to the recommendation that eating low-density foods in the
morning and avoiding high-density foods at night might aid in reducing
daily energy intake. 180