Because sustained low mood and stress change the chemistry of what food does for you. A 2003 paper in the Proceedings of the National Academy of Sciences, led by Mary Dallman, described how the acute stress response and the chronic one pull in different directions, and how chronically elevated glucocorticoids act on the brain in a way that increases the salience of pleasurable or compulsive inputs, including ingesting sucrose and fat. The pull toward comfort food during a hard stretch isn't imagination. The reward those foods deliver has genuinely been turned up.
The short answer
Sustained stress and low mood raise the reward value of sweet and fatty food specifically, which is why the urge is so consistent about what it wants. But this is only half the story. A substantial share of people respond to distress by eating less rather than more, and which group you fall into says nothing about your self-control.
What comfort food actually does
The Dallman paper's central observation is a split between timescales. Acutely, glucocorticoids inhibit further activity in the stress axis. Chronically, across days, their action on the brain is directly excitatory, and one of the things they excite is the pull toward pleasurable and compulsive activity. Sucrose and fat sit squarely in that category.
The paper also traces a feedback loop that makes the pattern self-sustaining. Intra-abdominal fat stores appear to act as an indirect metabolic signal back to the stress axis, which is part of why the comfort-food response gets reinforced rather than fading out. This is a mechanism with a physical basis, not a metaphor about emotional weakness. Cortisol's broader role in a maintenance phase, including the parts that get overstated, is covered in what cortisol actually does to weight regain.
Acutely, stress hormones dial things down. Chronically, they dial the reward from sweet and fatty food up.
The other half of people eat less
Here's the finding that gets left out of most articles on this. A 1994 study by Arthur Stone and Kelly Brownell, published in Psychology and Health, took multiple measurements a day from adults rather than asking them to recall a week afterward, and found what the authors called the stress-eating paradox. People were more likely to eat less than usual in response to a stressful daily problem than to eat more. More striking, as the severity of the stressor increased, the likelihood of eating more didn't change at all, while the likelihood of eating less rose substantially.
Broadly, roughly a third to 40% of people increase intake under stress. The rest hold steady or eat less. So if you're someone who loses their appetite completely during a hard week, nothing is wrong with you, and if you're someone who reaches for the freezer, that isn't a discipline problem either. These are two normal branches of the same response.
That split matters practically. If sadness makes you eat less, the risk in a maintenance phase isn't the hard week itself. It's the rebound afterward, when appetite returns to a body that's been under-fed for several days, and that swing is easy to misread as a sudden loss of control. Something similar happens after a GLP-1, which is why a sudden return of hunger is usually a signal rather than a failure.
Sadness, stress, and boredom aren't one trigger
They get lumped together as emotional eating, but they behave differently and they don't respond to the same thing. Acute stress often suppresses appetite outright. Sustained low mood tends to raise the pull of specific foods over days rather than minutes. Boredom is a different animal again, more about an absence of stimulation than about a negative feeling, and it responds to changing what's happening rather than to reassurance.
Knowing which one you're actually in is most of the work. The response that helps a lonely evening does nothing for an under-stimulated Sunday afternoon, and vice versa.
Why it's always the same kind of food
People almost never comfort eat plain rice. The mechanism runs through the reward system, so the foods that get amplified are the ones that produce a strong reward signal in the first place, which in practice means sweet, fatty, or both. That specificity is actually useful information: an urge attached to one particular food is far more likely to be an emotional one than a physical one, since real hunger is much less fussy. The specific mechanisms behind sugar cravings overlap heavily with this one.
What this means for maintenance
Three practical consequences. First, a hard stretch is a predictable event rather than a surprise, so it can be planned for the way you'd plan for a holiday or a work trip. Second, the direction of your own response is worth knowing, because eating less during a rough week and eating more are opposite problems needing opposite responses. Third, and most usefully, several days of unusual eating during a genuinely hard period is a small input into a long trend, and it looks much smaller on a chart than it feels at the time.
How OffRamp helps
OffRamp's Regain Radar exists precisely for weeks like this. It plots your weigh-ins as a trend rather than as a series of verdicts, so a rough stretch reads as a wobble in a line instead of a number that ruins your morning. The daily protein floor does the other half of the job, especially for people whose appetite disappears under stress, because a floor gives you something concrete to aim at on a day when nothing sounds good, and it's a minimum rather than a limit, so it never adds a rule to a week that already has enough going on. If the low mood itself is persistent rather than passing, that's worth raising with a doctor or your prescriber, and no tracking app is a substitute for that conversation.
