Overweight in cats - an often underestimated risk

Did you know that more than 50% of all domestic cats in Germany are overweight? Overweight is not just a cosmetic issue, but a serious health hazard for your cats.

Table of contents

Why is overweight dangerous?

Current studies show that overweight cats have a significantly higher risk of:

  • Diabetes mellitus – common consequence in obese cats
  • Osteoarthritis and joint pain – Overload and other factors limit the mobility of obese cats
  • Heart and breathing problems – especially in obese older cats
  • Reduced life expectancy – Reduced lifespan by up to 2 years in obese cats

How do I recognize overweight in cats?

Veterinarians work with the Body Condition Score (BCS) – a scale from 1 to 9.

  • Optimal 4-5
  • Overweight 6-7
  • Obesity 8–9

A simple test for at home:

  • Ribs are difficult to feel → indication of overweight
  • Waist not visible from above → warning sign

Nutrition and exercise - the two adjusting screws

  • Calorie reduction: Special diet food with high protein and low fat content
  • Feeding management: small portions, no constant food availability
  • Promote exercise: Play rod, food labyrinths, raised lying areas

But beware: No radical diets – too rapid weight loss can easily lead to fatty liver (hepatic lipidosis) in cats, a life-threatening disease.

Diabetes mellitus – common consequence in obese cats

Why Can Overweight Lead to Diabetes Mellitus?

  1. Insulin resistance

  • An increased proportion of fat, especially in the abdominal area, leads to a reduced sensitivity of the cells to insulin. Insulin is responsible for regulating the blood sugar level in the blood and ensures that the blood sugar gets into the cells.
  • Fat cells release messengers that have a pro-inflammatory effect as well as hormones that inhibit the effect of insulin.
  • At the same time, the concentration of a hormone sinks (“Adiponectin). Adiponectin increases the sensitivity of the cells to insulin and has an anti-inflammatory effect. A low level of this hormone therefore increases the risk of developing diabetes.

  1. Impairment of glucose tolerance

  • The insulin resistance caused by the fat cells means that glucose is less well absorbed by cells in muscle, fat and liver tissue.
  • The pancreas reacts with an increased insulin production and release.

  1. Exhaustion of the insulin-producing cells in the pancreas

  • In the long term, the permanent overproduction of insulin leads to damage to the insulin-producing cells in the pancreas
  • In addition, protein aggregates (amyloids) are deposited in the insulin-producing cells, which impair their function and ultimately lead to the death of the cells. This can lead to an insulin deficiency.

  1. Development of diabetes mellitus

The combination of insulin resistance and subsequent insulin deficiency leads to the development of diabetes mellitus.

Frequency and Risk Factors

  • Studies show that overweight cats have a 3 to 5 times higher risk of developing diabetes mellitus.
  • Particularly at risk are:
    • Tomcats
    • Tomcats and cats in middle and older age
    • Certain breeds such as Burmese
    • Tomcats and cats with a relatively inactive lifestyle and high-calorie feeding

Clinical Relevance

  • Obesity is now considered the most important modifiable risk factor for diabetes mellitus in cats
  • Weight reduction has been shown to improve insulin sensitivity and, in the case of early diagnosed diabetes, can even lead to remission (regression), so that no more insulin needs to be given.

Summary

Obesity in cats promotes the development of diabetes mellitus through insulin resistance, chronic hyperinsulinemia, fatigue of insulin-producing cells, and amyloid deposits.
Preventive weight control is therefore one of the most effective measures to significantly reduce the risk of diabetes in cats.

Osteoarthritis and joint pain – a common consequence in overweight cats

Frequency of chronic joint inflammation in cats

  • Osteoarthritis is widespread in cats: Radiological examinations show signs of degenerative joint changes in over 60% of cats over 6 years of age.
  • Overweight is a significant risk factor for the occurrence and progression of these diseases.
  • Studies in veterinary medicine indicate that obesity contributes to the development of osteoarthritis not only through overload, but also through metabolic and inflammatory mechanisms – similar to humans and dogs.

Relationship between obesity and the development or worsening of osteoarthritis and joint pain in cats:

  1. Mechanical stress on the joints

  • Overweight leads to increased mechanical stress on the joint structures, especially the hip, knee, and elbow joints.
  • This chronic overload accelerates cartilage abrasion and the development of degenerative changes.
  • Cats often compensate for pain for a long time, but then show reluctance to move, reduced jumping ability, or changes in grooming behavior.

  1. Metabolic and inflammatory effects of adipose tissue

  • Adipose tissue is not only an energy store, but also an active endocrine (hormone-releasing) organ.
  • In obese cats, adipokines and pro-inflammatory cytokines are increasingly released.
  • These messengers promote systemic and local inflammatory conditions in the joints, which increase cartilage degeneration and pain sensitivity.

  1. Chronic low-grade inflammation

  • Obesity induces a state of permanent, mild systemic inflammation.
  • This promotes synovitis (inflammation of the synovial membrane) and intensifies degenerative processes in the cartilage.

Symptoms of chronic joint inflammation in overweight cats

  • Overweight cats are more likely to show reduced mobility, lameness, or changes in behavior (e.g. less climbing, jumping, or less grooming).
  • Obesity worsens the quality of life by increasing pain.

Weight reduction has been shown to lead to a clinical improvement in mobility and pain relief in cats with chronic joint inflammation (osteoarthritis).

Summary

Obesity promotes the development and progression of osteoarthritis in cats through:

  • Mechanical overload of the joints,
  • metabolic-inflammatory effects of adipose tissue, and
  • systemic low-grade inflammatory conditions.

Consistent weight control and adapted management (diet, exercise therapy, pain management) are central measures to prevent or alleviate osteoarthritis and joint pain in cats.

Obesity and the development or worsening of heart and breathing problems in cats:

Relationship between overweight and heart and breathing problems in cats

  • Concrete epidemiological data for cats are less comprehensive than for dogs and humans, but veterinary studies show clear connections:
    • Obesity measurably reduces respiratory function (Feldman et al., 2007; Lecoindre & Paradis, 2015).
    • Overweight cats are more likely to experience shortness of breath and reduced resilience (Laflamme, 2012).

In cardiological examinations, obesity is classified as a risk factor for hypertension and secondary heart problems.

Effects on the respiratory system

  • Mechanical restriction:
    • Excessive fat deposits in the thorax and abdomen reduce the mobility of the diaphragm and the elasticity of the lungs.
    • Result: reduced vital capacity, shallower breathing and lower oxygen supply (similar to “Pickwick syndrome” in humans).
  • Airway obstruction:
    • Obesity increases the risk of obstructive airway diseases by narrowing the upper airways (e.g. fat deposits in the pharyngeal area).
    • Symptoms may be exacerbated, especially in brachycephalic cat breeds (e.g. Persians).
  • Hypoxia and exercise intolerance:
    • Obese cats show shortness of breath more quickly during exertion or stress, sometimes also resting dyspnea.

Effects on the cardiovascular system

  • Increased cardiac work:
    • Obesity leads to an increased cardiac output, as the organism has to supply the enlarged tissue with blood.
    • This puts a strain on the left heart in particular and favors hypertrophic adaptation (thickening of the heart muscle).
  • High blood pressure (hypertension):
    • Studies show that overweight cats are more likely to have arterial hypertension
    • The combination of high blood pressure and increased cardiac work can contribute to hypertrophic cardiomyopathy (HCM) or worsen existing heart diseases.
  • Dyslipidemia and inflammation:
    • Obese cats often show changes in fat metabolism (↑ triglycerides, ↑ cholesterol) as well as chronic low-grade inflammatory conditions
    • These factors contribute to endothelial dysfunction and can promote the progression of cardiovascular diseases.

Symptoms of the effects of overweight on breathing and cardiovascular function

  • Overweight cats have an increased risk of dyspnea, exercise intolerance, and cardiovascular diseases.
  • Even moderate weight reduction has been shown to improve:
    • the respiratory rate and oxygen supply,
    • the cardiac output and
    • the general quality of life.

Summary

Obesity in cats affects both the respiratory mechanics (through mechanical restriction and airway narrowing) and the cardiovascular system (through increased cardiac work, hypertension, and inflammatory processes).
It is therefore considered a major risk factor for respiratory complaints and cardiovascular diseases.
Weight control is one of the most important preventive and therapeutic measures to prevent or improve heart and breathing problems in cats.

Obesity shortens life expectancy in cats

  • Concrete long-term data in cats are more limited than in dogs, but obesity is considered a major factor for morbidity and mortality in small animal medicine. Obese cats have a significantly increased risk of premature causes of death, especially from diabetes, osteoarthritis, and secondary diseases.
  • This is well documented scientifically in humans and dogs.
  • In general, overweight is associated with a reduced life expectancy of 1.5 to 2.5 years.

Translated to cats, this means: Obesity significantly reduces life expectancy, with the combination of metabolic diseases, orthopedic problems, and increased susceptibility to infection making the greatest contribution.

Causes of reduced life expectancy in overweight cats

  1. Multi-organ stress
    • Overweight cats are more likely to develop metabolic disorders (e.g. insulin resistance, dyslipidemia) that affect a variety of organ systems.
    • Obesity leads to chronic “low-grade” inflammation through the release of pro-inflammatory cytokines from adipose tissue (TNF-α, IL-6, Leptin), which are involved in the development of numerous diseases.
  2. Increased disease risk
    • Diabetes mellitus type 2: Obesity is the most important risk factor for the development of diabetes in cats.
    • Orthopedic diseases: Joint stress and inflammatory processes lead to osteoarthritis and chronic pain.
    • Heart and respiratory diseases: Obesity increases the risk of hypertension, heart muscle diseases, and breathing problems.
    • Neoplasias: Studies suggest an increased risk of certain tumors (e.g. mammary tumors in cats, more documented in dogs and humans).
  3. Organic late sequelae
    • Permanent insulin resistance → β-cell exhaustion in the pancreas → Manifestation of diabetes.
    • Chronic stress on the heart and vessels → cardiovascular complications.
    • Limited mobility → Reduction of muscle mass and further metabolic deterioration.

Summary

Obesity in cats is far more than a cosmetic problem. It is the most common nutrition-related disease in domestic cats and is considered a crucial risk factor for a shortened lifespan. It promotes the development of numerous chronic diseases, puts a strain on organ functions, and limits the quality of life.
Preventive weight control and consistent weight management are therefore crucial to enable cats to live a longer and healthier life.

Even a moderate weight reduction can:

  • improve insulin sensitivity,
  • alleviate joint and breathing problems,
  • relieve the cardiovascular system and respiratory function
  • significantly increase the quality of life and prognosis.