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Chronic conditions

Pet Obesity: The Most Common Preventable Disease

Why excess weight shortens life, how to assess body condition honestly, and how to manage safe weight loss.

By Dr Hana LindqvistVeterinary review: Dr Elena Marsh9 min readPublished 2026-02-26Updated 2026-09-03

Why it matters

Obesity is associated with osteoarthritis, diabetes mellitus in cats, respiratory compromise, anaesthetic risk, urinary disease and reduced lifespan. A landmark lifetime study in Labrador Retrievers found that dogs kept lean lived around two years longer than their overweight littermates.

Assess body condition, not the scales alone

Use the nine-point body condition score: you should be able to feel ribs easily under a thin layer of fat, see a waist from above, and see an abdominal tuck from the side. Most owners systematically underestimate their own animal's score.

Safe weight loss

Target around one to two percent of body weight per week in dogs and cats. Rapid weight loss in cats risks hepatic lipidosis, a serious liver condition — never crash-diet a cat.

  • Weigh food with kitchen scales; measuring cups are wildly inaccurate
  • Count treats within the daily calorie total, keeping them under 10%
  • Ask your vet to calculate calorie targets rather than following pack guidelines
  • Use puzzle feeders to slow eating and increase activity
  • Recheck weight every two weeks and adjust

Rule out medical causes

Hypothyroidism in dogs and Cushing's disease can cause weight gain, and arthritis reduces activity. A veterinary assessment before starting a diet plan avoids treating a symptom while missing the cause.

References

  1. Kealy et al., Effects of diet restriction on life span and age-related changes in dogsJournal of the American Veterinary Medical Association, 2002
  2. WSAVA Body Condition Score chartsWorld Small Animal Veterinary Association