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    In the first lifelong canine diet-restriction study, researchers discovered that Labrador retrievers fed 25% less food than their siblings in a control group had a median life span of nearly 2 years longer. The conclusion among participating scientists: less food in the bowl adds more--and healthier--years to dogs' lives.

    Researchers at the Purina Pet Institute in St. Louis, in collaboration with scientists from several major universities, published results of this 14-year study that shows that a dog's median life span can potentially be extended by 15% when the dog is kept to its ideal body condition by carefully monitoring food intake.

    RELATED: 16 Ways to Keep Your Dog Healthy

    "We all know that obesity, whether human or canine, is bad for health," says Dennis F. Lawler, DVM, a veterinary scientist who, along with principal investigator Richard D. Kealy, PhD, directed the Purina Lifespan study. "What's exciting about this study is that, for the first time, we have shown scientifically that by simply feeding to maintain the ideal body condition throughout a dog's life, we can increase length of life while delaying the visible signs of aging. That's powerful stuff."

    Pet expert Arden Moore is the award-winning author of The Kitten Owner's Manual and Real Food for Dogs (both Storey Books, 2001) and a graduate of The Humane Society of the United States's "Pets for Life" national companion-animal training program. To keep your dog fit and healthy, follow her ten food bowl tips.

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    Tip 1:

    Ask your veterinarian if your dog's body condition is ideal. If not, work with your vet to set up a weight loss plan to return him to that goal condition.

    RELATED: Caring For an Older Pet

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    Tip 2:

    Read the food label for recommended daily portions based on your dog's weight, and look at the package back for an illustration of a dog at ideal body condition to see if your dog matches up. It's more important to feed your dog to his ideal body condition than to a certain weight.

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    Tip 3:

    Feed the dog, not the bowl. Use a measuring cup when scooping the dry food into the food bowl so you know exactly how much you are serving. Get a smaller bowl if you think it looks too empty.

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    Tip 4:

    Perform a weekly check on your dog to make sure you can easily feel his ribs. Examine his profile to see if his abdomen is tucked behind the rib cage, and stand over him to see if he has a clearly defined waist behind the ribs.

    RELATED: How to Tell if Your Pooch is Too Pudgy

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    Tip 5:

    Adjust the amount you serve your dog to maintain ideal body condition. No matter what he weighs, if body condition is at the ideal point, the weight will be acceptable.

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    Tip 6:

    Team up sound nutrition with regular fitness to keep your aging dog in shape. M. Christine Zink, DVM, PhD, an expert in canine sports medicine, recommends that you follow these steps to maximize the health benefits of walking your dog.

    RELATED: 10 New Exercises to Try With Your Pet

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    Tip 7:

    Warm up your dog's muscles by starting with a 5-minute slow pace. Then take a 10- to 15-minute brisk walk, ending with a 5-minute slow pace to cool down the muscles.

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    Tip 8:

    Keep your dog on a brisk pace for the majority of the walk so that he trots rather than saunters. This gait exercises both sides of your dog's body and provides him with a cardiovascular workout.

    RELATED: Pet Games That Make Exercise Fun

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    Tip 9:

    Aim for 20-minute daily walks rather than hour-long walks on weekends. A little exercise every day is better than a lot of exercise once or twice a week.

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    Next: People Foods Dogs Can Eat Too

    Tip 10:

    Have the vet give your older dog the okay before substantially increasing his exercise.