PRIOR DAYS INTAKE HAS MACRONUTRIENT-SPECIFIC DELAYED NEGATIVE FEEDBACK EFFECTS ON THE SPONTANEOUS FOOD-INTAKE OF FREE-LIVING HUMANS

A fundamental issue in understanding how energy balance is accomplishe d involves comprehending how changes in intake affect subsequent intak e. This was investigated in free-living humans by reanalyzing the data previously collected from 733 adults who were paid to maintain a 7-d diary of everything they ate and when they ate it. Food energy intake during a day was found to only mildly affect intake on the subsequent day (mean r = -0.07, P < 0.001), but was more strongly negatively rela ted to intake occurring on the second (mean r = -0.18, P < 0.001) and third day (mean r = -0.10, P < 0.001) afterward. Each macronutrient wa s shown to have a maximal negative relationship with subsequent intake of that same macronutrient, with 2-d lag mean autocorrelations equal to -0.11, P < 0.001 for carbohydrate, equal to -0.18, P < 0.001 for fa t, and equal to -0.13, P < 0.001 for protein. These effects on daily i ntake were found to result from separate negative feedback effects on meal size and frequency. The results suggest that intake affects subse quent intake by persistently setting a long-term bias that, integrated over time, produces a net shift in intake.