Loss of appetite is the dominant eating problem in Alzheimer's disease, while frontotemporal dementia typically brings the opposite — increased appetite and cravings, especially for sweets. Dementia with Lewy bodies follows a different pattern still, where weight loss shows up early and carries a higher risk of hospitalization. These distinctions matter for caregivers trying to figure out what's normal and when to call a doctor. A person with Alzheimer's who stops eating is following the disease's typical course, but the same symptom in someone with frontotemporal dementia or Lewy body dementia points to a different underlying problem — one that needs its own kind of attention.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- How Alzheimer's Changes Eating Differs From Other Dementias
- Why Frontotemporal Dementia Causes Overeating, Not Appetite Loss
- What Weight Loss Means in Lewy Body Dementia
- How Appetite Loss Changes as Alzheimer's Progresses
- What to Watch For and When to Talk to a Doctor
- Frequently Asked Questions
How Alzheimer's Changes Eating Differs From Other Dementias
Alzheimer's disease typically causes decreased appetite, early difficulty swallowing (called dysphagia), and progressive weight loss as the disease advances, though a smaller group of patients develops increased appetite instead, according to a 2026 clinical review on dementia and eating behavior. This makes Alzheimer's the dementia type where appetite loss is the expected pattern, not the exception. Frontal-variant frontotemporal dementia (fv-FTD) and semantic dementia move in the opposite direction.
A caregiver-questionnaire study comparing 43 Alzheimer's patients, 23 fv-FTD patients, and 25 semantic dementia patients found eating-behavior changes were significantly more common in both FTD groups than in Alzheimer's, with symptoms showing up more often across four of five measured domains, according to Ikeda et al. in the Journal of Neurology, Neurosurgery & Psychiatry. Within that same research, Alzheimer's patients showed reduced appetite, while fv-FTD and semantic dementia patients showed increased appetite as an early, defining feature of the disease rather than appetite loss. The practical takeaway: a family watching for appetite loss as a dementia warning sign is watching for the right thing in Alzheimer's, but the wrong thing in frontotemporal dementia, where weight gain and food-seeking behavior are the earlier red flags.
Why Frontotemporal Dementia Causes Overeating, Not Appetite Loss
Frontotemporal dementia damages the brain regions that normally regulate impulse control and eating behavior, which is why its eating symptoms run opposite to Alzheimer's. A caregiver-questionnaire study of fv-FTD patients found that a notable appetite increase led to measurable weight gain in 30% of participants, and 91% showed a change in food preference — typically craving sweet foods, according to a study summarized by MedBridge. The order symptoms appear also differs by subtype. In fv-FTD, the first eating-related symptom to show up is usually altered eating habits or increased appetite.
In semantic dementia, the first change is altered food preference, with appetite increase following later, according to the Ikeda et al. research. Alzheimer's disease does not follow a clear symptom order, though swallowing difficulty tends to emerge relatively early in its course. For caregivers, this means a loved one with frontotemporal dementia who suddenly craves sweets or overeats is showing a recognized early symptom of that disease — not a behavioral quirk unrelated to the diagnosis.
What Weight Loss Means in Lewy Body Dementia
Dementia with Lewy bodies (DLB) shows a weight-loss pattern that is both common and consequential. A large cohort study of 11,607 patients with Alzheimer's disease, vascular dementia, or DLB found weight loss around the time of dementia onset occurred in 25.5% of the whole group and was most common among patients with DLB, according to Soysal et al., reported via Anglia Ruskin Research Online. Weight loss raised the risk of emergency hospitalization across all three dementia types, with a hazard ratio of 1.14.
Notably, weight loss was linked to higher mortality in Alzheimer's disease but not in DLB, even though it was most prevalent in DLB. That distinction matters because it means weight loss in a Lewy body dementia patient carries a different clinical weight than the same symptom in an Alzheimer's patient, even though both need medical follow-up. A separate controlled study compared eating and swallowing problems in 29 DLB patients against 33 Alzheimer's patients using a 40-item caregiver questionnaire, specifically to test whether DLB produces a distinct eating-problem profile rather than assuming it overlaps with Alzheimer's, according to research published in International Psychogeriatrics.
How Appetite Loss Changes as Alzheimer's Progresses
Appetite loss in Alzheimer's disease does not worsen in a straight line. Clinicians note that eating-habit and appetite changes tend to intensify through the moderate stage of the disease but can paradoxically decrease again in the most severe stage, according to a clinical summary cited by Today's Geriatric Medicine. This means a caregiver may see appetite problems ease up late in the disease, which reflects the disease's course rather than improvement. In advanced dementia generally, across all types, eating problems are common and arrive earlier than other major complications.
Eating difficulties are reported in roughly 86% of patients with advanced-stage dementia and tend to emerge sooner and more often than complications like fever or pneumonia, according to the British Dietetic Association. A separate nursing-home study found that 80% of residents with advanced dementia and feeding problems had chewing or swallowing difficulty, and 48% had poor oral intake. This progression pattern means the timing of appetite changes carries information. Appetite loss appearing early and steadily worsening fits Alzheimer's moderate-stage course, while a sudden shift, or a shift toward overeating, points toward a different dementia type worth raising with a clinician.
What to Watch For and When to Talk to a Doctor
Because appetite direction differs so sharply by dementia type, tracking which way it moves is one of the more useful things a caregiver can report to a doctor: Reporting the direction and timing of appetite changes, not just that an appetite change occurred, gives a clinician more to work with when distinguishing between dementia types or flagging a complication that needs attention.
- Steady appetite loss with swallowing difficulty and gradual weight loss fits the typical Alzheimer's pattern.
- Increased appetite, sweet-food cravings, or new weight gain in a person with cognitive changes fits the pattern seen in frontal-variant frontotemporal dementia.
- A change in food preference appearing before any appetite change fits the early pattern seen in semantic dementia.
- Early, pronounced weight loss combined with a Lewy body dementia diagnosis warrants closer monitoring, since it raises the risk of emergency hospitalization.
- A sudden reversal of a long-standing appetite problem in late-stage Alzheimer's is a known part of disease progression, not necessarily a new issue.
Frequently Asked Questions
Does weight loss always mean a worse outcome in dementia?
Not uniformly. In a cohort of 11,607 patients, weight loss was linked to higher mortality in Alzheimer's disease but not in dementia with Lewy bodies, even though it raised emergency-hospitalization risk across all three dementia types studied, according to Soysal et al.
Can someone with frontotemporal dementia also lose their appetite later on?
The research packet describes increased appetite and food-preference changes as the defining early features of frontal-variant FTD and semantic dementia, in contrast to the appetite loss seen in Alzheimer's disease, according to Ikeda et al.
