A double-blind, placebo-controlled test of 2 d of calorie deprivation: effects on cognition, activity, sleep, and interstitial glucose concentrations.
BACKGROUND
Anecdotal information and limited research suggest that short-term caloric deprivation adversely affects cognition. However, this issue has not been studied using double-blind, placebo-controlled procedures, because the formulation of a calorie-deficient feeding regimen identical to one with calories is impossible using ordinary foods. Therefore, test meals varying in caloric content, but indistinguishable in sensory characteristics, were formulated using hydrocolloid-based gels as the principal structural component.


OBJECTIVE
The purpose of this study was to examine the effects of 2 d of near-total caloric deprivation on cognitive function, satiety, activity, sleep, and glucose concentrations in a controlled environment.


METHODS
A double-blind, placebo-controlled crossover study of caloric deprivation was conduced in a controlled environment for 48 h. Cognitive function in 27 healthy young subjects was assessed repeatedly with standardized tests of vigilance, reaction time, learning, memory, logical reasoning, mood, and satiety. Wrist-worn monitors were used to assess ambulatory vigilance, activity, and sleep. Interstitial glucose concentrations were assessed continuously with a minimally invasive monitor.


RESULTS
When the subjects received the near calorie-free diets, mean calorie consumption totaled 1311 kJ (313 kcal) over the testing period. During the fully fed treatment sessions, the subjects consumed a mean of 9612 kJ/d (2294 kcal/d), which matched their individual, daily energy requirements. Satiety and interstitial glucose concentrations were lower during the calorie-deprived diet (P < 0.001) than during the fully fed diet. There were no detectable effects of calorie deprivation on any aspect of cognitive performance, ambulatory vigilance, activity, or sleep. The mood states assessed, including fatigue, were not affected by calorie deprivation.


CONCLUSIONS
Cognitive performance, activity, sleep, and mood are not adversely affected in healthy humans by 2 d of calorie-deprivation when the subjects and investigators are unaware of the calorie content of the treatments.
Lieberman
Harris R
HR
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA. harris.lieberman@us.army.mil.
Caruso
Christina M
CM
Niro
Philip J
PJ
Adam
Gina E
GE
Kellogg
Mark D
MD
Nindl
Bradley C
BC
Kramer
F Matthew
FM
D000328:Adult; D001288:Attention; D001786:Blood Glucose / Q000378:metabolism*; D031204:Caloric Restriction; D003071:Cognition / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010919:Placebos; D011930:Reaction Time; D012890:Sleep / Q000502:physiology*
D001786:Blood Glucose; D010919:Placebos