Can a High Lysine Diet Change a Dog’s Genes and Reduce Obesity?

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LysineIn our last post, we described some of the research performed by Hill’s Pet Nutrition that concluded that a diet with a high lysine to calorie ratio could change a dog’s gene expression from fat storing to fat burning. These results are certainly encouraging because they could potentially provide guidance on the types of diets that would help an overweight pet (or human, for that matter) to more quickly lose weight and keep it off.   If, in fact, diets high in lysine can impact a dog’s obesity related gene expression, then we would expect that the Hill’s study used a food that contains ingredients that are naturally high in lysine, right? Not so fast.


Foods High in Lysine

The food that was used in one of the Hill’s studies was the Hill’s Prescription Diet r/d Canine. Before we look at the ingredients in this food, it is helpful to list some foods that naturally contain high amounts of lysine.   Lysine is an essential amino acid, and therefore, good sources of lysine include mostly high-protein foods such as:

  • Red meats (e.g. beef)
  • Pork
  • Poultry
  • Lamb
  • Fish
  • Peas
  • Beans, including Soy beans
  • Amaranth and Quinoa
  • Milk and eggs


In comparison, the ingredients in the Hill’s Prescription Diet r/d Canine are:

Whole Grain Corn, Corn Gluten Meal, Chicken By-Product Meal, Soybean Mill Run, Powdered Cellulose, Soybean Meal, Chicken Liver Flavor, Dried Beet Pulp, Pork Flavor, Lactic Acid, Soybean Oil, Caramel color, DL-Methionine, L-Lysine, Potassium Chloride, Choline Chloride, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of vitamin C), Niacin Supplement, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Riboflavin Supplement, Folic Acid, Vitamin D3 Supplement), Calcium Carbonate, Iodized Salt, minerals (Manganese Sulfate, Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Calcium Iodate, Sodium Selenite), Taurine, L-Carnitine, Mixed Tocopherols for freshness, Phosphoric Acid, Beta-Carotene, Natural Flavors.


Unfortunately, there is very little overlap of foods naturally high in lysine with the ingredients listed in this recipe. And where there is an overlap, the quality and appropriateness is questionable, as evidenced by the use of Chicken By-Product Meal (as the chicken source) and Soybean Mill Run and Soybean meal as a cheap protein source. (For more on the use of Soy in dog food, read our ingredient analysis of soy here.) And forget about chicken liver flavor and pork flavor. Neither of these provides much nutrition, let alone protein and lysine.


We do however, notice that L-Lysine is an ingredient in the food. No doubt, this was added to boost the lysine levels in this food as a consideration to the lower quality and cheaper sources of proteins that are present. In the animal feed industry, lysine supplementation is a strategy that allows for the use of lower-cost (e.g. plant) proteins while maintaining high growth rates in the livestock. Said another way, adding lysine is a way to ‘cover’ for the use of cheaper protein ingredients.


Further analysis of the ingredients in the r/d Canine food suggests that this food is not one that I would want to feed my pet, under most circumstances. It is not appropriate at all for the carnivore dog, contains mostly corn, and contains no fruits or vegetables (for vitamins).


I would be interested to see the results of a study using a food containing higher quality, natural sources of lysine, with real meat or fish based proteins, fruits and vegetables, and free of cheap fillers and flavorings. I would bet that the dogs would enjoy their meals more, and be healthier overall in the long run. This is the approach that I would take anyway.


Thanks to Hill’s for conducting some innovative research. Shame on Hill’s for executing the food product so poorly.

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  1. Great post and totally agree with you – glad to see the research, but I won’t be feeding that dog food to my dogs.
    Sue recently posted…One Dog Organic Baker Giveaway and ReviewMy Profile

  2. Oh no. Those are definitely not ingredients I would like to see
    ღ husky hugz ღ frum our pack at Love is being owned by a husky!
    Jenna,Mark “HuskyCrazed” Drady recently posted…How do dogs show affection?My Profile

  3. Interesting findings. They have so many different foods, we have to go read some packages to see what the others contain.
    Emma recently posted…Valentine’s Day Stuffed KongsMy Profile

  4. OMG I actually gasped after reading the first four ingredients. Number one corn and soy are two of the most modified crops in this country. Number two, a solid protein source, not a by-product should be listed as the first ingredient.

    Truthfully, I’m not surprised that Hills would deceive their clients like this, but it is shameful that more people aren’t aware of the crap that is in their dog food and take steps to help stop this.
    Jodi recently posted…I Should Have Named HerMy Profile

  5. I’m thankful there are so many healthy dog foods on the market now. Dog owners are becoming more educated and have more options than ever. Thanks for highlighting these foods that fall short in providing good nutrition for our pets. We appreciate it!
    Elaine recently posted…15 Helpful Dog Park Tips – Keeping Dog Park Visits PositiveMy Profile

  6. This is a very educational post! I wonder if this is why dogs switched to a raw diet tend to lose excess weight soon after switching from kibble since the number one ingredient is raw meat (beef, lamb, chicken, etc)? I know Oz lost his few excess pounds when we switched and he has maintained keeping them off. Your thoughts?
    Oz the Terrier recently posted…Raw Bones and Dog Dental HealthMy Profile

    • My guess is that the primary driver of the weight loss was the switch to a higher protein/ lower carb food and not the extra lysine. In the short term, calorie deficits drive weight loss. Higher lysine, according to the studies, would make it easier for the dog to keep weight off as their bodies relearn to be fat burners instead of fat storers.

      There once was a study by Hills
      Food could cure obesity like pills
      Too much corn and soybeans
      Can they really change the dog’s genes?
      This food is not worth the bills
      steve recently posted…Can a High Lysine Diet Change a Dog’s Genes and Reduce Obesity?My Profile

  7. I applaud you for this informative article, and thank you for providing black on white proof that Hill’s dog food is below average crap, pardon my french. Before I took the initiative of reading dog food ingredient labels & becoming more knowledgeable in proper, healthy dog nutrition, I actually fed Hill’s kibble, as it came highly recommended by our former vet.
    Never again!!!
    Barbara Rivers recently posted…Keep Your Dog Safe From Chocolate This Valentine’s Day!My Profile

  8. I really didn’t have to read any further than corn as the first ingredient, to know it was bad! What a shame, I used to think of Hill’s as a quality food….but I actually haven’t for a while now. I thought maybe they’d change their ways, but apparently not.
    Jan K recently posted…Old Man WinterMy Profile

  9. This is disappointing….We always feel conflicted because it is a popularly recommended food, but the ingredients just aren’t there to support the high cost and number of people who recommend it!
    MyDogLikes recently posted…Breakfast in Bed: Full Moon Dog Treats Review & GiveawayMy Profile

  10. Interesting research, but I agree about the quality of the food. I hope more research comes out with higher quality foods.
    It’s Dog or Nothing recently posted…Valentine’s Day for You and Your DogMy Profile

  11. Wow, thank you for looking into R/D and explaining what you found. eye opener for sure. I’m sure the food I am feeding Nellie Purina OM is going to compare pretty close or R/D.
    Sand Spring Chesapeakes recently posted…Kissing Booth~Woodless WednesdayMy Profile

  12. Is that the food that some dogs tested out with good result? After having tried some foods that got high ratings for ingredients with poor result I think whether a food works for a dog or not depends on the dog. I have relaxed my requirements for the foods we feed.
    2 Brown Dawgs recently posted…Stuck In A Deep FreezeMy Profile

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