ADHD	Attention-deficit/hyperactivity disorder
DSM	Diagnostic and Statistical Manual of Mental Disorders
FFD	Few-foods diet
GI	Glycemic Index
GL	Glycemic Load
ICD	International Classification of Diseases
NOS	Newcastle–Ottawa Scale
PECOS	Population–Exposure–Comparator–Outcome–Study design
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
PROSPERO	International Prospective Register of Systematic Reviews
RoB 2	Cochrane Risk of Bias 2
ROBINS-I	Risk Of Bias In Non-randomised Studies—of Interventions