Researchers tested whether a natural supplement called conjugated linoleic acid (CLA) could help people with high body fat reduce how much new fat their bodies create. In a 12-week study with 65 adults, those taking CLA showed changes in their blood fat levels compared to those taking a placebo. Specifically, CLA appeared to slow down the body’s natural fat-making process and improved certain cholesterol markers. While the results are promising, the changes were modest, and more research is needed to understand if CLA truly helps people lose weight or keep it off long-term.

The Quick Take

  • What they studied: Does taking CLA supplements help reduce the amount of new fat your body creates, especially in people who carry extra body fat?
  • Who participated: 65 adults with higher-than-normal body fat percentages participated. They were randomly assigned to take either CLA supplements or a fake pill (placebo) for 12 weeks.
  • Key finding: People taking CLA showed measurable changes in their blood fat levels, suggesting their bodies made less new fat. Specifically, certain fatty acids decreased while others increased in ways that suggest improved fat metabolism.
  • What it means for you: CLA may help your body reduce its natural fat-making process, which could potentially support weight management efforts. However, this was a small study with modest changes, so CLA shouldn’t be viewed as a standalone weight-loss solution without combining it with healthy eating and exercise.

The Research Details

This was a double-blind, randomized controlled trial, which is considered one of the strongest types of scientific studies. Neither the participants nor the researchers knew who was taking the real CLA supplement and who was taking the placebo until the study ended. This prevents bias from affecting the results.

Participants were divided into two groups: one received CLA supplements for 12 weeks, while the other received identical-looking placebo pills. Before and after the study, researchers analyzed the fatty acids in participants’ red blood cells using a laboratory technique called gas chromatography, which can identify and measure different types of fats in the blood.

The researchers also looked at blood markers related to cholesterol and triglycerides (a type of fat in your blood) to understand how CLA affected overall fat metabolism. They used advanced statistical methods to connect changes in blood fats to changes in metabolic pathways—essentially the chemical processes your body uses to create and break down fats.

Understanding whether CLA actually changes how your body makes fat is important because it helps explain how the supplement might work. Rather than just measuring weight loss, this study looked at the biological mechanisms—the actual chemical changes happening in your body. This approach is more scientifically rigorous and helps researchers understand if CLA is truly affecting fat production or if any weight changes are from other factors.

This study has several strengths: it was randomized (reducing bias), double-blind (preventing expectation effects), and used objective laboratory measurements rather than relying on self-reporting. However, the sample size of 65 people is relatively small, which means results may not apply to everyone. The study lasted only 12 weeks, so we don’t know if benefits continue or fade over longer periods. The study also didn’t measure actual weight loss or body composition changes directly, only the chemical markers in blood.

What the Results Show

Compared to the placebo group, people taking CLA showed specific changes in their blood fatty acids. Two types of fatty acids (C16:1n7 and C18:1n9) decreased, while another type (C18:3n3) increased. All of these changes were statistically significant, meaning they were unlikely to have happened by chance.

These changes suggest that CLA successfully reduced the body’s natural process of making new fat from carbohydrates and other sources. This process, called de novo lipogenesis, is one way your body stores excess energy as fat. By slowing this process, CLA may help prevent excess fat storage.

The researchers also found connections between these fatty acid changes and improvements in blood cholesterol levels. For example, the increase in C18:3n3 was linked to lower LDL cholesterol (the “bad” cholesterol), which is generally considered beneficial for heart health.

The study identified specific patterns in blood metabolites (chemical markers) that predicted which people would respond best to CLA. These metabolite patterns were connected to changes in triglycerides and visceral adiposity index (a measure of deep belly fat). The findings suggest that CLA’s effects on fat metabolism involve multiple pathways in your body, including energy production cycles and fat breakdown processes. This indicates CLA doesn’t work through a single mechanism but rather affects several interconnected metabolic systems.

Previous research on CLA has shown mixed results for weight loss in humans, though some animal studies showed more dramatic effects. This study adds to the evidence by demonstrating that CLA does indeed affect the biological process of fat creation in humans. However, the changes observed were relatively modest compared to what some earlier studies suggested. This research helps clarify that while CLA does have measurable metabolic effects, these effects may be smaller than initially hoped for weight management purposes.

The study had several important limitations. First, it only lasted 12 weeks, so we don’t know if the effects continue, increase, or fade over months or years. Second, the study didn’t directly measure weight loss or changes in body fat percentage—only blood markers. Third, with only 65 participants, results may not apply to everyone, especially people of different ages, ethnicities, or health conditions. Fourth, the study didn’t track whether participants changed their eating or exercise habits during the study, which could affect results. Finally, CLA supplements can be expensive and may cause digestive side effects that weren’t thoroughly documented in this study.

The Bottom Line

Based on this research, CLA supplementation may help reduce your body’s natural fat-making process if you have elevated body fat. However, the evidence is moderate in strength. CLA should be considered as a potential complement to—not a replacement for—a healthy diet and regular exercise. If you’re interested in trying CLA, discuss it with your doctor first, especially if you take medications or have digestive sensitivities. Expect any benefits to develop gradually over weeks to months, not days.

This research is most relevant to adults with higher body fat percentages who are looking for additional tools to support weight management. It may be particularly interesting to people who have tried diet and exercise alone without satisfactory results. However, this study doesn’t provide strong evidence that CLA will help people with normal body fat percentages, and it may not be necessary for everyone. People with certain health conditions, digestive issues, or those taking specific medications should consult their healthcare provider before starting CLA supplements.

Based on this 12-week study, you would need to take CLA consistently for at least 3 months to potentially see measurable changes in blood fat markers. Any effects on actual weight loss or body fat reduction would likely take even longer. Most people should expect gradual changes rather than dramatic results. If you don’t notice any positive changes after 3-4 months of consistent use combined with healthy eating and exercise, CLA may not be effective for you personally.

Want to Apply This Research?

  • Track CLA supplement intake daily (yes/no), along with weekly measurements of waist circumference and monthly blood work markers like triglycerides and LDL cholesterol if available through your doctor. This combination tracks both the supplement use and the biological changes this research measured.
  • Start taking a CLA supplement daily as directed on the package, while simultaneously tracking your eating habits and exercise in the app. The app can help you maintain the healthy diet and exercise routine that makes CLA supplementation most effective. Set reminders for consistent daily intake, as the study required 12 weeks of regular use to see results.
  • Create a 12-week tracking period in the app. Log daily supplement intake, weekly body measurements, and monthly notes on energy levels and digestive comfort. After 12 weeks, review your data to see if you notice improvements in the tracked metrics. Consider getting blood work done before starting and after 12 weeks to measure the same markers (triglycerides, LDL cholesterol) that showed improvement in this study.

This research describes the effects of CLA supplementation on blood fat markers in a small study of 65 adults over 12 weeks. These findings do not constitute medical advice and should not replace consultation with your healthcare provider. CLA supplements are not FDA-approved medications and may cause side effects including digestive upset. Results may vary significantly between individuals. This study did not measure actual weight loss or long-term health outcomes. If you are pregnant, nursing, have liver disease, diabetes, or take medications, consult your doctor before starting CLA supplements. This summary is for educational purposes only and should not be used to diagnose or treat any medical condition.