Brain dopamine responses to ultra-processed milkshakes are highly variable and not significantly related to adiposity in humans

Ultra-processed foods high in fat and sugar have been theorized to be addictive due to their purported ability to induce an exaggerated post-ingestive brain dopamine response akin to drugs of abuse. Using [¹¹C]raclopride positron emission tomography (PET) displacement methods used to measure brain dopamine responses to addictive drugs, we measured striatal dopamine responses beginning 30 min after ingesting an ultra-processed milkshake high in fat and sugar in 50 young, healthy adults over a wide body mass index (BMI) range (20–45 kg/m²). Surprisingly, milkshake consumption did not result in a significant post-ingestive dopamine response in the striatum (p = 0.62) nor in any striatal subregion (p > 0.33), and the highly variable interindividual responses were not significantly related to adiposity (BMI: r = 0.076, p = 0.51; % body fat: r = 0.16, p = 0.28). Thus, post-ingestive striatal dopamine responses to an ultra-processed milkshake were likely substantially smaller than for many addictive drugs and below the limits of detection using standard PET methods.