Obesity Is Just As Bad As Smoking

The fact that obesity reduces lifespan is a well established fact in dogs and several other animal species. Dr. Kealy1 and others have shown, in a classic study, that thin Labs outlive overweight Labs by almost two years (13 years vs. 11 years on average).  I’ve always wondered when physicians would show a similar correlation in people.

They finally have. A recent article in the Lancet2 made the point. This is a gigantic study: The researchers reviewed 57 studies, for a total of 900,000 human patients in the US, Europe, Japan, etc. These results should therefore be reliable.

Moderate obesity (about one third overweight, or 50 to 60 pounds over the ideal) reduces human lifespan by about three years.
Severe obesity (double the ideal weight), reduces lifespan by 10 years, or about as much as smoking.

The body mass index (BMI) helps describe overweight and obesity. BMI is the weight (in kilograms) divided by the square of the height (in meters). A BMI greater than 50 kg/m2 defines obesity.

Mortality is the lowest for a BMI between 22.5 and 25 kg/m2. For each 5 kg/m2 increase of the BMI, mortality increases by 30 percent.
The most common causes of death in obese patients are heart attacks, strokes, diabetes, cancer, kidney disease, liver disease and COPD.

The authors of the study conclude with two striking facts:

  • By avoiding an increase of BMI from 28 to 35 kg/m2, an adult would live an average of two more years.
  • By preventing an increase of BMI from 24 to 32 kg/m2, lifespan would increase by an average of three years.

Why should we care as veterinarians?

The obesity epidemic probably affects vets and their staff as much as the rest of the population, but that’s not my point. I’m not a physician.
My point is, humans and pets suffer from the same obesity epidemic. Same causes, same symptoms, same consequences. Education, campaigns and warnings all seem to have failed somehow.

We know how to fix the problem, though. We have diets, medications, pamphlets. Yet it seems that the percentage of overweight and obese cats and dogs climbs year after year.

I don’t claim to have all the answers, but here are a few thoughts:

  • Most pets should be switched to a light diet after being spayed or neutered, since we know their metabolism will slow down.
  • Pets are becoming couch potatoes, just like people. Some kind of physical activity should be encouraged, if only leash walks.
  • Opening the kitchen door to let the dog eliminate in the back yard is the easy way out (no pun intended).
  • Daily food amounts should be measured with a real measuring cup, not just a scoop  Filling up the bowl whenever it looks empty is so 20th century

What other suggestions do you give your own clients in daily practice?


1. RD Kealy et al. “Effects of diet restriction on life span and age-related changes in dogs.” J Am Vet Med Assoc. 2002 May 1;220(9):1315-20
2. G. Whitlock et al. “Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies”. The Lancet. 2009, Vol 373, p. 1083-1096.

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