The physics and physiology behind “passive overconsumption” of fatty foods.
What the evidence says
- At equal calories (isoenergetic 240 kcal servings), foods’ satiety index ”correlated positively with the serving weight of the foods” (corrected 2026-09-19 from ”High energy density (many calories in small volume)”: `csi01` does not use the term; energy density is `csi02`’s subject, below)[1]
- In those equal-calorie servings, ”fat content was negatively associated” with satiety index scores, so higher-fat foods were less filling per calorie in this test[1]
- In the stomach, ”the volume of ingested food is detected by vagal afferents in the external muscle layers sensitive to stretch and tension”. Which ending does it is less settled: ”IMAs were thought to represent in-series tension receptors long before the functional proof of mechanosensitivity for IGLEs”, and ”it is now unclear how they are functionally different from IGLEs” (corrected 2026-09-19 from ”intramuscular arrays detect stretch”, stated flat)[2]
- Satiety index scores correlated ”negatively with palatability ratings”: a correlation across 38 foods (corrected 2026-09-19 from ”Palatability drives continued eating past satiety”, a causal reading the study does not test)[1]
- “Passive overconsumption” — people tend to eat a consistent food weight (`csi02`’s own hedge; a premise the review reasons from, not a finding it reports), so in the reported experiment a 30% reduction in energy density gave ”around 30% less” energy intake over two days while ”participants rated their hunger and fullness as similar” (corrected 2026-09-19 from ”30% higher energy density produces ~30% higher calorie intake”, the reverse direction of what was tested)[3]
- The “fat paradox”, in the review’s words: ”although fat induces strong pre-absorptive satiety signals these do not appear to be capable of preventing overconsumption when the diet contains high fat foods” (requoted 2026-09-19 from ”potent satiety signals … yet high-fat diets still cause overconsumption”)[4]
- The mechanism is ENERGY DENSITY, not mistimed signals — corrected 2026-09-02. Blundell & Tremblay attribute “passive overconsumption” to “high palatability and high energy density,” and report the experiment that separates them: given isocaloric high-fat or high-carbohydrate diets, energy intakes were approximately equal, so “high fat hyperphagia is largely caused by the high energy density rather than by the proportion of fat”[4]
- Because, in the review’s words, ”since fat is the most dense nutrient, fat contributes most to the energy density and therefore most to the phenomenon of passive overconsumption”, and the review adds a caution: ”But it should be remembered that a number of nutrient and sensory features of foods may contribute in differing degrees to the stimulation of hyperphagia” (corrected 2026-09-19 from ”not because of anything peculiar to fat itself”, which the caution contradicts)[4]