Researchers studied whether adding choline and L-carnitine supplements to cat food could help obese cats by changing their body chemistry. They compared 9 obese cats and 9 lean cats over 6 weeks, testing three different diets. While obese cats did show different chemical patterns in their blood compared to lean cats, the supplements didn’t fix these differences as much as scientists hoped. The findings suggest that obesity changes how a cat’s body processes certain chemicals, which might explain why overweight cats are at higher risk for a serious liver condition called hepatic lipidosis.

The Quick Take

  • What they studied: Whether adding choline and L-carnitine supplements to cat food could change the body chemistry of obese cats and make it more like lean cats
  • Who participated: 18 adult male neutered cats—9 that were obese (overweight) and 9 that were lean (healthy weight). All cats were fed the same amount of food for their body size.
  • Key finding: Obese cats had different levels of certain chemicals in their blood compared to lean cats, showing their bodies process things differently. While the supplements changed some chemical levels, they didn’t fix the main differences between obese and lean cats.
  • What it means for you: If you have an overweight cat, this research suggests that obesity changes how your cat’s body works at a chemical level. While these specific supplements didn’t solve the problem in this study, the findings help scientists understand why overweight cats are at risk for liver disease. Talk to your vet about weight management strategies for your cat.

The Research Details

Scientists gave 18 cats three different diets over 18 weeks total. Each diet lasted 6 weeks, with a 2-week break between diets to let the cats’ bodies return to normal. One diet had extra choline (a nutrient that helps the liver), one had L-carnitine (a substance that helps burn fat), and one was a regular diet with no supplements. The cats were divided into two groups: 9 obese cats and 9 lean cats. Every week, the researchers weighed the cats and checked their body condition. At the end of each 6-week period, they took blood samples and used special machines to measure hundreds of different chemicals in the blood.

This type of study is called a ‘crossover’ design because each cat got all three diets. This is a strong way to study supplements because you can compare how the same cat responds to different treatments. The researchers used advanced technology called mass spectrometry to measure the chemicals in the blood—think of it like a very detailed scanner that can identify thousands of different substances.

The scientists used statistical tests to figure out which differences between groups were real and not just due to chance. They looked at how obesity affected the results, how the supplements affected the results, and whether the supplements worked differently in obese versus lean cats.

This research approach is important because it shows exactly which chemicals change when cats become obese and whether supplements can fix those changes. By measuring hundreds of chemicals at once (called metabolomics), scientists can see the ‘fingerprint’ of how obesity affects a cat’s body. This helps explain why obese cats get sick more often and why certain supplements might or might not help.

This study has several strengths: it used a careful crossover design where each cat served as its own control, it measured many chemicals using precise technology, and it included a washout period between treatments. However, the study only included 18 cats and only male cats, so the results might not apply to female cats or larger groups. The study was relatively short (6 weeks per treatment), so we don’t know if longer supplementation might have different effects. The researchers were careful about their statistical analysis and set a high bar for what counts as a real finding.

What the Results Show

The most important finding was that obese cats had higher levels of several chemicals related to something called ‘one-carbon metabolism’—a process in the body that helps with many important functions. Specifically, obese cats had more of these chemicals: s-adenosylhomocysteine, cysteine, cystine, and two forms of glutathione (a protective substance in cells). This pattern suggests that obesity disrupts how a cat’s body handles these important chemicals.

When the researchers gave the supplements, they found some changes: choline supplementation changed the levels of betaine (another chemical in the one-carbon pathway), and L-carnitine changed the levels of a chemical called decarboxylated S-adenosylmethionine. However, these changes were relatively small and didn’t fix the main problems seen in obese cats. Both supplements appeared to help with how the cats’ bodies burned fat, but this didn’t translate into major improvements in the one-carbon metabolism pathway.

The body weight and body condition scores of the cats didn’t change during the study, which makes sense because all cats were fed the same amount of food. The study wasn’t designed to test whether supplements help cats lose weight, but rather to see if they change body chemistry.

The researchers noticed that both supplements seemed to improve how the cats’ bodies used fat for energy, which is encouraging. This suggests that L-carnitine and choline might help with fat metabolism even if they don’t fix all the chemical imbalances caused by obesity. The fact that the supplements affected different chemicals (choline affected one pathway, L-carnitine affected another) shows they work through different mechanisms in the body.

Previous research suggested that choline and L-carnitine supplements might help prevent hepatic lipidosis (a serious liver condition where fat builds up in the liver) in obese cats. This study confirms that obesity does change body chemistry in ways that might increase disease risk. However, this is one of the first studies to carefully measure whether these supplements can reverse those chemical changes. The findings suggest that while these supplements might help with fat burning, they may not be a complete solution for the metabolic problems caused by obesity.

This study only included 18 cats, all of which were male and neutered. Results might be different for female cats or intact cats. The study only lasted 6 weeks per treatment, so we don’t know if longer-term supplementation might have different effects. The cats were all fed the same amount of food, so this study doesn’t tell us whether supplements help with weight loss. The study used commercial cat food, so results might differ with other types of diets. Finally, this was a study in cats, so we can’t automatically assume the same supplements would work the same way in other animals or in humans.

The Bottom Line

Based on this research, choline and L-carnitine supplements alone may not be enough to fix the chemical imbalances caused by obesity in cats. However, they may help with fat burning. The strongest recommendation is weight management through proper diet and exercise, which is the proven way to prevent obesity-related problems. If you’re considering supplements for your obese cat, talk to your veterinarian. These supplements appear safe but may work best as part of a complete weight management plan rather than as a standalone treatment. Confidence level: Moderate—this is one study in a small group of cats.

Cat owners with overweight or obese cats should care about this research, especially those worried about hepatic lipidosis (a serious liver condition in obese cats). Veterinarians who treat obese cats should be aware that these supplements may have limited effects on the metabolic problems caused by obesity. People considering supplements for their cats should understand that supplements alone may not solve obesity-related health issues. This research is less relevant for owners of lean, healthy-weight cats.

In this study, changes in blood chemistry appeared within 6 weeks, but the changes were modest. If you were to try these supplements with your cat, you might see some changes in blood chemistry within 4-6 weeks, but you shouldn’t expect dramatic improvements in your cat’s health or weight. Real improvements in an obese cat’s health typically take months of consistent weight management. Talk to your vet about realistic timelines for your specific cat.

Want to Apply This Research?

  • Track your cat’s weekly weight and body condition score (ask your vet to teach you how to assess this). If using supplements, record the supplement type, dose, and date started. Note any changes in energy level, appetite, or coat quality. This helps you and your vet see if supplements are having any real-world effects.
  • If your cat is overweight, the most important change is adjusting food portions and increasing activity. Use the app to set a target weight loss goal (typically 1-2% of body weight per week is safe for cats) and track progress weekly. Record what type of food and how much your cat eats daily. If considering supplements, log when you start them and monitor for any changes.
  • Weigh your cat weekly at the same time of day and track the trend over months. Take monthly photos from the same angle to visually track body condition changes. If using supplements, keep notes on any changes in behavior, energy, or health. Schedule vet check-ins every 4-6 weeks to monitor progress and adjust the plan. Use the app to share this data with your veterinarian.

This research is from a scientific study in cats and should not be used to diagnose or treat any condition in your pet. The findings suggest that choline and L-carnitine supplements have limited effects on the metabolic changes caused by obesity in cats. Always consult with your veterinarian before starting any supplements or making dietary changes for your cat. This article is for educational purposes only and is not a substitute for professional veterinary advice. If your cat is overweight or you’re concerned about hepatic lipidosis or other health conditions, please contact your veterinarian for personalized guidance.