Long-term effects of provided low and high glycemic load low energy diets on mood and cognition

Energy-restricted low glycemic load diets are being used increasingly for weight loss. However, the long-term effects of such regimens on mood and cognitive performance are not known. We assessed the effects of low glycemic load {(LG)} and high glycemic load {(HG)} energy-restricted diets on mood and cognitive performance during 6 months of a randomized controlled trial when all food was provided. Subjects were 42 healthy overweight adults (age 35+/-5 years; {BMI} 27.8+/-1.6 kg/m(2)) with a mean weight loss of 8.7+/-5.0% that did not differ significantly by diet randomization. Mood was assessed by using the Profile of Mood States {(POMS)} questionnaire. Cognitive performance was assessed by using computerized tests of simple reaction time, vigilance, learning, short-term memory and attention, and language-based logical reasoning. Worsening mood outcome over time was observed in the {HG} diet group compared to the {LG} for the depression subscale of {POMS} (p=0.009 after including hunger as a covariate). There was no significant change over time in any cognitive performance values. These findings suggest a negative effect of an {HG} weight loss diet on sub-clinical depression but, in contrast to a previous suggestion, provide no support for differential effects of {LG} versus {HD} diets on cognitive performance.