Energy Expenditure in ADHD KidsTuesday, March 23, 2010
I have repeatedly posted on the relationship between Attention Hyperactivity Deficit Disorder (ADHD) and obesity. We see a remarkable number of adults with this disorder in our bariatric clinic and, as blogged before, treating this disorder is often a key step in helping these patients manage their weight.
In kids, this disorder is often characterized by substantial hyperactivity, which would be expected to burn more calories. But what about the impact of ADHD on resting energy expenditure (REE) and the thermogenic effect of food (together accounting for about 60% if not more of the daily calories burnt)?
This question was addressed by my colleague Thomas Mueller and other researchers from the University of Alberta in a paper just published online in Eating and Weight Disorders.
Mueller and his team studied 12 pre-pubertal boys with untreated ADHD of the hyperactive-impulsive type and 12 control boys without ADHD. In addition, they examined an independent group of 60 boys with ADHD.
On average, REE was 6.5 kcal/kg fat free mass/day higher in the ADHD compared to the control group. However, there was no difference in the thermogenic effect of food between groups. Neither age nor restlessness explained the differences in REE.
Despite the higher REE (and likely higher activity energy expenditiure due to the innate restlessness that comes with this condition), boys with ADHD had similar BMI levels compared to non-ADHD reference groups.
Thus, this paper shows that despite a notably greater energy expenditure, ADHD kids are not generally leaner, clearly suggesting that they manage to make up for their greater energy needs through higher caloric intake.
One may well speculate that as these kids become older and their REEs (and activity expenditures?) decrease, persistence of a higher caloric intake than their non-ADHD peers may well make them more prone to obesity as adults.
How and why REE is elevated in ADHD clearly deserves further study. I’d certainly appreciate hearing from any of my readers, who have experience with the ingestive behaviour of ADHD kids.