L-Carnitine and Canine Weight Loss

What Does L-Carnitine

You will know that L-Carnitine and canine weight loss is connecte, if you have been looking at weight loss dog foods. Virtually all of them contain L-carnitine supplements.

But what exactly is L-carnitine and why is it used in canine weight loss diets? Those are the questions I will be addressing here.

What Is L-Carnitine?

L-carnitine, or levocarnitine, is the biologically active form of the vitamin-like coenzyme carnitine (dextrocarnitine, or D-Carnitine, is the inactive form). Because of its structural similarity to amino acids, it's frequently classified as one, but this is technically incorrect.

True amino acids are used in protein synthesis and fall into two groups: Essential amino acids are those that need to be provided through dietary sources, while non-essential amino acids can be synthesized in the body provided that the necessary "building blocks" are present.

Dogs can obtain L-carnitine from food, but they are also abel to synthesize it from the essential amino acids lysine and methionine. Adequate levels of vitamin C and certain B vitamins are also necessary to produce carnitine.

As far as dietary sources are concerned, red meats such as beef or lamb contain by far the highest levels of L-carnitine. In fact, the amount of L-carnitine found in beef is almost twenty times greater than what's present in chicken and four times greater than the amounts in pork. Poultry, fish, and dairy products contain moderate amounts of L-carnitine, while plant foods such as vegetables, fruits, and grains contain only negligible amounts.

That said, L-carnitine deficiency is rare in healthy dogs even if no red meat is fed. As long as there are sufficient levels of quality proteins in the diet, dogs have all the building blocks necessary to synthesize their own L-carnitine.

Functions of L-Carnitine

As previously mentioned, L-carnitine is not used in protein synthesis like true amino acids.

Its primary function is to transport fatty acids into the cellular mitochondria where the fats are oxidized and converted to energy. In other words, L-carnitine helps the body turn fat into energy.

It also possesses antioxidant properties, protecting cell membranes against lipid peroxidation, and there is some evidence that L-carnitine supplements can lower blood triglyceride levels. It is theorized that increased levels of L-carnitine result in more fat converted to energy and less fat stored by the body.

L-Carnitine for Canine Weight Loss

L-carnitine is found in countless weight loss supplements and in virtually all weight loss dog foods. It is thought to promote weight loss in several ways:

• Greater energy and reduced fatigue.
• More fat burned for energy and less fat stored.
• Increased lean muscle mass boosts metabolic rate.

Several studies have shown that dogs losing weight on a diet supplemented with L-carnitine lose more weight, including a greater percentage of body fat, while retaining more lean muscle mass than the control group eating the same weight loss dog food minus L-carnitine supplementation.

For instance, in one study with overweight dogs, the L-carnitine group lost 6.4% of their body weight after 7 weeks of dieting, while the group eating the same diet without L-carnitine lost only 1.8% body weight.

L-Carnitine Supplements vs. Dietary Sources

While not a magic bullet for combating canine obesity, I am satisfied that there is sufficient evidence to indicate that L-carnitine is beneficial to canine weight loss. What's less clear to me is whether supplementation is necessary.

It may be possible to achieve the same results by feeding a diet high in animal proteins with correspondingly high levels of natural L-carnitine.

To date, studies examining the efficacy of L-carnitine-supplemented weight loss diets have only looked at conventional canine weight loss diets with high levels of carbohydrate, moderate protein content, and low fat levels.

Would L-carnitine supplementation still provide the same benefits if a high protein, low carbohydrate diet was used?

In an attempt to gain more insight into that question, let's take a brief look at another nutrient that is increasingly recommended for weight loss.

Conjugated linoleic acid (CLA) comprises a family of fatty acids derived from linoleic acid that has been shown to provide similar weight loss benefits as L-carnitine. And like L-carnitine, CLA is found primarily in meat—especially red meat—and dairy products.

There are several studies demonstrating that dogs losing weight on a diet supplemented with CLA lose more body fat and retain more lean body mass than the control group not receiving CLA supplements.

BUT: These benefits were apparent only when CLA was added to traditional canine weight loss diets with 44-50% carbohydrate and 24-28% protein.

When a high protein (51%), low carbohydrate (21%) diet was supplemented with CLA, the CLA group fared no better than the control group eating the same diet without CLA supplements.

However, both high protein groups (with and without CLA) lost substantially more weight and body fat than both of the high carb groups (even though the high carb group receiving CLA did far better than the group not receiving CLA supplements). This suggested to the researchers that the "macronutrient change from high-carbohydrate to high-protein content has a greater effect on increasing weight loss than does the addition of CLA to a diet." (see References).

I look forward to a similar study conducted with L-carnitine supplements. In the meantime, I recommend adding L-carnitine to canine weight loss diets, but not at the expense of high protein levels.

Given a choice between a dog food with high protein and low carbohydrate levels that includes little or no L-carnitine supplements and a dog food that's high in carbs and L-carnitine supplements, I strongly suggest you choose the former.

High protein and low carbohydrate levels are more important for canine weight loss than any supplement. Also, it's much easier to add an L-carnitine supplement to a dog food with excellent, species-appropriate ingredients and optimal macronutrient ratios than add protein to a weight loss dog food that's high in L-carnitine, but too low in protein.

Reference - The American Society for Nutritional Sciences J. Nutr. 134:2087S-2089S, August 2004, High-Protein Low-Carbohydrate Diets Enhance Weight Loss in Dogs: By Tiffany Linn Bierer and Linh M. Bui.