SYMPTOM
Increased appetite
Eating noticeably more than usual or showing persistent hunger despite consuming regular meal portions.
Endocrine
Several hormonal conditions can directly stimulate appetite through their effects on metabolism and hunger signalling. Hyperadrenocorticism produces polyphagia through the metabolic effects of excess cortisol, often alongside increased thirst and urination. Diabetes mellitus may produce increased appetite as cells are unable to utilise glucose effectively despite elevated blood levels, creating a state of cellular hunger despite adequate caloric intake. Hyperthyroidism in cats dramatically increases metabolic rate, driving increased food consumption that may not keep pace with energy expenditure.
Gastrointestinal Malabsorption
Conditions that impair the absorption of nutrients from the digestive tract can produce increased appetite as the body attempts to compensate for inadequate nutritional uptake. Exocrine pancreatic insufficiency, inflammatory bowel disease, intestinal lymphangiectasia, and other malabsorptive conditions can create a situation where the animal eats normally or excessively but fails to derive adequate nutrition from its food. The increased appetite may be accompanied by changes in stool quality, weight loss, or altered coat condition.
Medication-Related
Certain medications can significantly increase appetite as a side effect. Corticosteroids are particularly well known for producing polyphagia, often dramatically so, alongside increased thirst and urination. Some anticonvulsant medications, progestational compounds, and other drugs may similarly influence appetite regulation. The increased appetite in these cases typically corresponds temporally with the medication's administration and may resolve when the medication is discontinued or adjusted.
Behavioural or Psychological
Boredom, anxiety, competition with other pets for food, or learned food-seeking behaviours can all produce patterns of increased appetite that are not driven by metabolic need. Animals with limited environmental enrichment may fixate on food as a primary source of stimulation. Competitive feeding environments may encourage rapid eating and food guarding. Changes in household routine that affect feeding schedules or the animal's daily structure may also influence apparent appetite levels.
Parasitic
Heavy intestinal parasite burdens can divert nutrients from the host animal, potentially producing increased appetite as the body attempts to compensate for the nutritional losses. While this is more commonly significant in young animals or those with heavy infestations, chronic low-grade parasitism may contribute to increased food-seeking behaviour alongside other signs such as poor coat quality, intermittent gastrointestinal signs, or failure to maintain condition despite adequate food intake.
Why timing matters
Early observation
A gradual increase in appetite may initially appear as simply a healthy interest in food or a preference change. The animal may start finishing meals more quickly, seeking additional food, showing increased interest in human food, or becoming more persistent in food-seeking behaviour. At this early stage, distinguishing a genuine pathological increase in appetite from normal variation, seasonal changes in energy needs, or responses to dietary changes can be challenging. Noting whether the increased appetite is accompanied by other changes — in weight, thirst, energy levels, or stool quality — can help contextualise whether the appetite change represents an isolated shift or part of a broader pattern.
Later presentation
As polyphagia becomes more established, the animal's food-seeking behaviour may become more pronounced and potentially disruptive. Scavenging, counter-surfing, stealing food from other pets, consuming non-food items, and persistent vocalisation for food may develop. Despite the increased intake, the animal may lose weight if the underlying cause involves metabolic acceleration or malabsorption — the paradox of weight loss despite increased eating is a particularly notable pattern. Alternatively, if the increased appetite is not accompanied by a condition preventing weight gain, progressive obesity may develop with its own secondary health implications.
The trajectory of increased appetite depends on its underlying cause. Endocrine conditions tend to produce gradually worsening polyphagia as the hormonal imbalance progresses. Malabsorptive conditions may show fluctuating appetite depending on the activity of the underlying gastrointestinal disease. Medication-related polyphagia typically remains stable while the medication continues and resolves when it stops. Behavioural causes may fluctuate with environmental changes. Tracking whether the appetite increase is progressive, stable, or variable, and whether it responds to changes in feeding routine, can help characterise the underlying driver.
Conditions commonly associated
Cushings Disease in Dogs
Diabetes Mellitus in Dogs
Diabetes Mellitus in Cats
Hyperthyroidism in Cats
Exocrine Pancreatic Insufficiency (EPI)
Increased appetite (polyphagia) is a prominent feature of EPI as the body signals for more food in response to inadequate nutrient absorption despite normal food intake.
Exocrine Pancreatic Insufficiency (EPI)
Dogs with EPI are often ravenously hungry as their bodies cannot extract nutrition from food.
When to explore further
Increased appetite accompanied by weight loss despite adequate or increased food intake represents a particularly significant pattern, as it suggests that either the metabolic rate has increased beyond what food intake can satisfy, or that nutrients are not being properly absorbed or utilised by the body.
When polyphagia develops alongside increased water consumption and increased urination, this triad of polyphagia, polydipsia, and polyuria may suggest an endocrine or metabolic condition that is affecting multiple physiological systems simultaneously.
A sudden and dramatic increase in appetite that represents a clear departure from the animal's established eating patterns may carry different implications from a gradual shift in food interest, particularly if it develops without obvious environmental or dietary changes.
Increased appetite accompanied by changes in stool quality — larger volumes, altered consistency, increased frequency, or the presence of undigested material — may suggest that the digestive system is not processing food effectively, driving the body to seek additional intake.
When increased appetite develops in an older cat alongside other changes such as weight loss, restlessness, increased vocalisation, or a palpable thyroid nodule, the combination of signs may suggest a hypermetabolic state that is characteristic of certain endocrine conditions in this species.
Monitoring both appetite and body weight over time provides complementary information — appetite alone tells only part of the story, while the relationship between food intake and weight change reveals whether the body is effectively utilising the nutrition consumed. Keeping a food diary that records what and how much the animal eats, alongside regular weight measurements, can build a dataset that helps characterise whether the increased appetite is productive or paradoxical. Noting any concurrent changes in thirst, urination, stool quality, energy levels, and coat condition rounds out the picture and may reveal patterns that connect the appetite change to a broader physiological shift.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS