It’s been estimated that losing as little as 2% of your body weight in fluids can negatively effect athletic performance. But what about cognitive performance? A study recently published in the journal Medicine & Science in Sports & Exercise looks at how dehydration influences brain functions.

Researchers analyzed 33 studies involving 413 subjects who experienced different degrees of dehydration ranging from 1% to 6% of body weight lost through fluids. Although findings varied, fluid deficits of more than 2% body weight appeared to have an impact on executive function, motor coordination and attention.