CLA is a type of polyunsaturated fatty acid found in meat and dairy, often marketed as a weight loss supplement.
While research shows it may lead to modest fat loss—around 0.2 pounds per week—the effect is minimal, and potential side effects like digestive discomfort and metabolic concerns should be considered.
Keep reading for a detailed breakdown of how CLA works, its effectiveness, and whether it’s worth taking.
The Science Behind CLA and Weight Loss
CLA gained popularity as a weight loss supplement due to early animal studies that showed significant fat reduction, sparking interest in its potential benefits for humans.
While initial excitement led to widespread supplementation, human trials have painted a more complex picture, showing much smaller effects.
To understand whether CLA truly helps with weight loss, it’s important to examine its rise in popularity, what the research says, and how its effects compare between animals and humans.
How CLA Became Popular for Fat Loss
The idea that CLA could help with weight loss started with promising animal research.
In the 1990s, studies on mice showed that CLA supplementation significantly reduced body fat while increasing lean mass.
This led to speculation that it might work similarly in humans. Given that CLA naturally occurs in meat and dairy, it seemed like a safe and accessible way to promote fat loss.
Supplement manufacturers quickly capitalized on these findings, formulating CLA supplements in concentrated doses and marketing them as an effective weight-loss aid.
Fitness enthusiasts and dieters began using CLA with the expectation that it would replicate the dramatic fat loss seen in animal studies.
However, as more research emerged, it became clear that CLA's effects in humans were far less dramatic than originally hoped.
Animal Studies: Promising but Not Directly Applicable
Animal studies fueled much of the excitement surrounding CLA.
In particular, research on mice and rats showed striking reductions in body fat when they were given CLA supplements.
One study found that mice receiving CLA experienced a 70% reduction in body fat over six weeks compared to those not receiving it.
Another study observed similar fat loss in pigs, suggesting that CLA might have a universal effect across different species.
These results were exciting because they suggested that CLA could enhance fat metabolism, prevent fat storage, and promote lean muscle growth.
However, while animal studies provide useful insights, they don't always translate to human physiology.
Mice and other animals process fats and energy differently than humans, and they were given much higher doses of CLA relative to their body weight than what humans typically consume.
Human Studies: More Modest Results
When CLA was tested in humans, the results were far less dramatic.
While some studies did show slight reductions in body fat, the effect was not nearly as significant as what was seen in animal models.
A meta-analysis of 18 human studies found that consuming 3.2 grams of CLA per day resulted in an average fat loss of just 0.09 kg (0.2 pounds) per week, or less than half a pound per month.
This level of fat loss is minimal compared to what can be achieved through dietary changes and exercise.
Additionally, many of the studies noted that CLA had no impact on overall body weight—meaning that while some fat loss was observed, it wasn't substantial enough to cause meaningful changes in total body composition.
Several human studies also examined how CLA might influence muscle mass.
While some suggested a slight increase in lean body mass, the effects were small and inconsistent.
Unlike in animals, where CLA supplementation often resulted in both fat loss and muscle gain, human studies have not demonstrated these benefits reliably.
Why Do CLA’s Effects Differ Between Animals and Humans?
The differences in CLA's effects between animals and humans likely come down to several key factors:
- Metabolism Variations: Humans metabolize fats differently than rodents and other test animals. The way CLA interacts with human enzymes and hormones may not be as effective for reducing fat.
- Dosing Differences: The doses given to animals were significantly higher than those typically recommended for humans. If humans consumed CLA at similar relative doses, the side effects would likely outweigh the benefits.
- Diet and Lifestyle Factors: Animals in lab studies have controlled diets and activity levels, whereas humans have a variety of dietary patterns and lifestyle habits that influence weight loss.
Meta-Analysis Findings: What the Numbers Say
To get a clearer picture of CLA’s effectiveness, researchers have conducted multiple meta-analyses—comprehensive reviews that compile results from numerous studies.
The most widely cited meta-analysis examined 18 randomized controlled trials and found that:
- A daily dose of 3.2 grams led to an average fat loss of 0.2 pounds per week.
- No significant reduction in total body weight was observed.
- Most studies lasted between 6 and 12 months, with no substantial improvements over time.
This confirms that while CLA might have a small effect on fat loss, it is not a powerful weight-loss tool.
Its impact is much smaller than diet, exercise, or other evidence-backed weight loss methods.
How CLA Might Work: Proposed Mechanisms
CLA is believed to influence fat metabolism through several biological pathways, including increasing fat breakdown, reducing fat storage, and altering energy expenditure.
These mechanisms have been observed in laboratory and animal studies, but their effectiveness in humans remains debated.
While some research supports CLA's role in fat loss, inconsistencies in human studies suggest its impact may be limited. Below, we’ll explore the key ways CLA is thought to work.
Fat Oxidation: How CLA May Promote Fat Breakdown
One of the primary claims surrounding CLA is that it enhances fat oxidation, the process by which stored fat is broken down and used for energy.
Several studies suggest that CLA may stimulate certain enzymes and proteins involved in this process, including:
- Carnitine palmitoyltransferase (CPT): A key enzyme that helps transport fatty acids into mitochondria, where they are burned for energy.
- Hormone-sensitive lipase (HSL): An enzyme that breaks down stored fat (triglycerides) into free fatty acids that can be used for energy.
- Peroxisome proliferator-activated receptors (PPARs): Proteins that regulate fat metabolism and may influence how efficiently fat is burned.
In animal studies, CLA supplementation has been shown to increase these metabolic processes, leading to enhanced fat breakdown.
However, human studies have produced mixed results. Some research suggests a slight increase in fat oxidation, while others have found no significant changes.
This inconsistency suggests that if CLA does impact fat oxidation in humans, the effect is relatively small.
Reduced Fat Storage: Potential Inhibition of Fat-Storing Enzymes
Another proposed mechanism of CLA is its ability to prevent fat accumulation by inhibiting enzymes responsible for fat storage.
Research indicates that CLA may suppress the activity of lipoprotein lipase (LPL), an enzyme that facilitates the uptake of fat into adipose tissue.
By reducing LPL activity, CLA may theoretically limit the amount of fat stored in the body.
Some studies also suggest that CLA may influence adipogenesis, the process by which new fat cells are formed.
CLA has been shown to interfere with the development of fat cells in lab studies, potentially reducing the body's ability to store excess fat.
However, in human trials, the effect has been inconsistent, with some studies reporting minimal or no impact on fat storage.
Changes in Metabolism: Possible Effects on Energy Expenditure
Beyond breaking down fat and reducing fat storage, CLA is also thought to influence overall energy expenditure.
Some research suggests that CLA may slightly boost metabolic rate, allowing the body to burn more calories at rest.
This effect has been observed in animals, where CLA supplementation led to increased calorie expenditure and reduced body fat.
However, in humans, the impact on metabolism appears to be minimal.
Most studies show little to no significant increase in resting metabolic rate (RMR) with CLA supplementation.
Even in cases where a small increase is observed, it is unlikely to contribute meaningfully to weight loss without additional dietary and lifestyle changes.
Are These Mechanisms Effective in Humans?
While the above mechanisms provide a theoretical basis for how CLA might work, human studies have yet to confirm these effects conclusively.
Unlike in animal models, where CLA supplementation has led to significant fat loss, human results have been far less dramatic. Several factors could explain this discrepancy:
- Variability in Dosage and Duration: Many studies use different CLA doses and trial lengths, making it difficult to establish consistent results.
- Individual Differences: Genetic factors, lifestyle habits, and baseline metabolic rates likely play a role in CLA’s effectiveness.
- Compensatory Mechanisms: The human body has complex regulatory systems that may counteract any fat-burning effects of CLA, limiting its impact.
Who Might Benefit from CLA?
While CLA is not a magic solution for weight loss, certain groups may see some benefits from incorporating it into their diet or supplement routine.
Those looking for a slight fat loss boost, individuals who naturally consume CLA-rich foods, and people using it as part of a structured diet and exercise plan may find it somewhat helpful.
However, expectations should remain realistic, as the effects are relatively modest compared to other weight-loss strategies.
People Looking for a Slight Fat Loss Boost
For individuals who are already following a structured weight-loss plan and are looking for an extra edge, CLA may provide a small but measurable reduction in body fat over time.
Studies suggest that a daily dose of 3.2 grams can result in an average fat loss of about 0.2 pounds per week, which translates to less than half a pound per month.
While this amount may not be significant on its own, it could be a worthwhile addition for those who are patient and consistent.
CLA may help maintain lean muscle mass while promoting slight fat loss, potentially making it beneficial for those in the later stages of a fat-loss journey where every bit of progress counts.
However, if someone expects rapid or dramatic results, CLA will likely be disappointing.
It should be seen as a minor supplement to an already well-structured fitness and nutrition program rather than a standalone solution.
Those Getting CLA Naturally Through Diet vs. Supplementing
Before turning to CLA supplements, it’s important to consider whether you’re already getting enough through your diet.
CLA naturally occurs in the meat and dairy products of ruminant animals such as cows, sheep, and goats. Some of the best dietary sources of CLA include:
- Grass-fed beef (contains significantly more CLA than grain-fed beef)
- Lamb and veal
- Full-fat dairy products like milk, butter, yogurt, and cheese
- Eggs (contain small amounts)
For individuals who consume these foods regularly—especially those who prioritize grass-fed or pasture-raised animal products—their CLA intake may already be sufficient.
In these cases, supplementation may not provide additional benefits beyond what is naturally obtained from food.
On the other hand, those who follow low-fat diets, vegan diets, or consume mostly grain-fed animal products may not be getting much CLA from food alone.
These individuals might consider supplementation if they’re interested in CLA’s potential fat-loss effects, though the overall impact remains relatively small.
Individuals Using CLA Alongside Diet and Exercise
CLA is most effective when combined with a structured diet and regular exercise.
It is not a replacement for calorie control or physical activity but may serve as a complementary tool.
Those who follow a high-protein diet and engage in resistance training might benefit slightly more, as CLA has been linked to improved body composition in some studies.
Here’s how CLA might fit into different fitness approaches:
- Strength training & muscle building: Some research suggests that CLA may help with muscle preservation while reducing fat, making it potentially useful for those undergoing a cutting phase in bodybuilding.
- Calorie-controlled weight loss: Those following a moderate calorie deficit may see a minor fat-loss benefit from CLA when used consistently.
- Endurance athletes & active individuals: Since CLA is involved in fat metabolism, it might have some role in fuel utilization during prolonged physical activity, though research in this area is limited.
That said, anyone considering CLA should first focus on proven weight-loss strategies, such as maintaining a caloric deficit, eating whole, nutrient-dense foods, and staying active.
Only after these foundations are in place should CLA be considered as a supplemental aid.
Who Might Not Benefit from CLA?
While some individuals might find CLA slightly useful, others are unlikely to see any meaningful benefits. CLA is probably not worth the investment for:
- People expecting rapid or dramatic fat loss – The weight-loss effects are very modest and take time.
- Those unwilling to maintain a healthy diet and exercise routine – CLA does not work in isolation.
- Individuals with metabolic concerns (e.g., insulin resistance, inflammation) – Some studies suggest CLA may worsen metabolic markers in certain individuals.
- Anyone looking for an all-natural approach – CLA is naturally present in food, but supplement forms are chemically altered, which may be a concern for those avoiding processed products.
CLA Dosage for Weight Loss
The effectiveness of CLA for weight loss depends not just on taking it but also on the correct dosage and consistency over time.
Research suggests that taking at least 3 grams per day may lead to small fat loss benefits, while higher doses up to 6.4 grams per day have been used in studies without major safety concerns.
However, CLA is not a fast-acting supplement, and those who use it should be prepared for gradual results rather than immediate changes.
Recommended CLA Dosage for Fat Loss
Most studies examining CLA's effects on body fat have used doses in the range of 3.2 to 6.4 grams per day.
The minimum effective dose appears to be around 3 grams per day, with no significant additional fat loss observed at much higher doses.
- 3.2 grams per day – Considered the standard dosage that has been shown to lead to a small reduction in body fat over time.
- Up to 6 grams per day – Some studies have used doses in this range with no major safety concerns, but higher doses do not necessarily mean greater fat loss.
For those who get some CLA from their diet (such as from grass-fed beef or dairy), supplementation may not need to be as high.
However, individuals who consume minimal dietary CLA may benefit more from supplementation at the lower end of this range.
How Long Does It Take to See Results?
Anyone taking CLA for fat loss needs to set realistic expectations, as the results tend to be slow and modest. Studies suggest that:
- Fat loss of approximately 0.2 pounds per week can be expected with regular CLA supplementation.
- Over the course of six months, this could amount to a total fat loss of 2–4 pounds—a small but measurable effect.
- The effects tend to plateau after 6–12 months, meaning CLA does not continue producing results indefinitely.
Because CLA works subtly, most people will not notice immediate changes in body weight.
Instead, its effects may become more noticeable over several months when combined with a consistent diet and exercise routine.
The Importance of Consistency in Supplementation
For CLA to have any impact, it must be taken daily over an extended period.
Skipping doses or taking CLA sporadically is unlikely to produce any noticeable results.
Since CLA's effects build up gradually, the best approach is to:
- Take the full daily dose in one serving or split it into two smaller doses. Some supplements suggest taking CLA with meals, while others recommend taking it at any time of the day.
- Use CLA consistently for at least 12 weeks before evaluating its effectiveness. Most studies assessing CLA's fat-loss effects have lasted between 12 and 52 weeks.
- Pair CLA with a healthy diet and exercise for the best results. CLA alone does not produce dramatic fat loss, so combining it with a structured weight-loss plan is essential.
CLA and Diet: Can You Get Enough from Food?
Since CLA naturally occurs in certain animal-based foods, some people may already consume adequate amounts through their diet without needing supplements.
The amount of CLA in food, however, varies based on factors such as how the animals were raised and the types of foods they were fed.
Understanding which foods provide CLA and how dietary intake compares to supplement doses can help determine whether additional supplementation is necessary.
Best Dietary Sources of CLA
CLA is found primarily in the meat and dairy products of ruminant animals—those that chew cud, such as cows, sheep, and goats.
The highest concentrations are found in grass-fed and pasture-raised animals, as their diet naturally boosts CLA content compared to grain-fed livestock.
Some of the best dietary sources include:
- Grass-fed beef – One of the richest sources, with up to 500% more CLA than grain-fed beef.
- Lamb and veal – Also high in CLA, particularly if pasture-raised.
- Full-fat dairy products – Including milk, butter, yogurt, and cheese, particularly from grass-fed cows.
- Eggs – Contain small amounts of CLA, though not as much as meat and dairy sources.
The CLA content in these foods is affected by the animal’s diet.
Cattle that are grass-fed produce significantly more CLA in their milk and meat than those raised on grain-based feed.
If increasing dietary CLA intake is the goal, opting for grass-fed meat and full-fat dairy products is the best approach.
How Much CLA Is in a Typical Diet vs. Supplements?
While CLA is present in common foods, the amount consumed through diet is usually much lower than what is provided by supplements. Here’s how they compare:
- A typical omnivorous diet that includes dairy and meat provides about 150–200 mg of CLA per day.
- Diets high in grass-fed beef and dairy may provide up to 500 mg per day, depending on portion sizes and frequency of consumption.
- In contrast, CLA supplements typically contain 3,200–6,400 mg (3.2–6.4 grams) per day, which is 10–30 times more than what is obtained from food.
This significant difference means that someone relying solely on dietary sources of CLA would need to consume large amounts of grass-fed meat and dairy to approach the levels used in clinical studies.
Is Supplementing Necessary If You Eat CLA-Rich Foods?
For those who eat a diet rich in grass-fed meat and full-fat dairy, CLA intake will be naturally higher, but still unlikely to reach the levels used in weight-loss research.
If the goal is simply to maintain a balanced diet with moderate CLA intake, eating these foods is sufficient.
However, supplementation might be considered if:
- Weight loss is the primary goal, and a person wants to match the doses used in clinical studies (3.2 grams or more per day).
- A person follows a low-fat or dairy-free diet, significantly reducing their natural CLA intake.
- Dietary CLA sources are limited due to cost or availability, as grass-fed meat and dairy can be expensive.
For many people, focusing on whole food sources of CLA is a more balanced and health-conscious approach than taking high-dose supplements.
However, those specifically looking for the fat-loss effects associated with CLA may need to supplement, as it is difficult to achieve the studied doses through diet alone.
Should You Take CLA for Weight Loss?
CLA is often marketed as a fat-loss supplement, but research suggests its effects are modest at best.
While some individuals might see minor benefits, others may not experience any noticeable changes.
Before deciding whether to take CLA, it’s important to consider whether you fall into a group that could benefit, what to look for when purchasing a supplement, and when to consult a healthcare provider.
Who Might Benefit from CLA?
Certain individuals may find CLA slightly helpful, especially if they have realistic expectations about its effects. Those who may benefit the most include:
- People looking for a small fat-loss boost – If you’re already following a structured diet and exercise plan, CLA may help with slight reductions in body fat over time (around 0.2 pounds per week).
- Individuals who struggle to get CLA from food – Those who consume minimal dairy or meat, particularly from grass-fed sources, may have lower natural CLA intake and could consider supplementation.
- Fitness enthusiasts trying to preserve lean muscle – Some evidence suggests that CLA may help retain muscle mass while reducing fat, making it potentially useful for individuals in a calorie deficit.
However, CLA is not ideal for everyone. The following individuals are unlikely to see meaningful benefits or may even experience negative effects:
- Those expecting dramatic weight loss – CLA alone does not lead to significant reductions in body weight. If you're looking for noticeable fat loss, diet and exercise remain far more effective.
- People with metabolic health concerns – Some studies suggest CLA may increase insulin resistance or markers of inflammation in certain individuals, potentially worsening conditions like prediabetes or metabolic syndrome.
- Anyone who dislikes taking long-term supplements – CLA’s effects are slow and cumulative, meaning consistent use over several months is necessary before any noticeable results occur.
Considerations Before Buying a CLA Supplement
If you decide to take CLA, choosing the right supplement is crucial. Not all CLA products are created equal, and some may be more effective or safer than others.
Here are key factors to consider before making a purchase:
- Dosage and Purity – Look for a supplement that provides at least 3.2 grams of CLA per serving, as this is the amount shown in research to have any effect on fat loss. Avoid underdosed products.
- Type of CLA Used – Most supplements contain CLA derived from safflower oil, but the ratio of active CLA isomers varies. Look for a brand that provides a well-researched isomer blend (typically cis-9, trans-11 and trans-10, cis-12 CLA).
- Third-Party Testing – Since the supplement industry is not strictly regulated, choose a product that has been tested by independent labs for purity and ingredient accuracy. Brands that carry NSF, USP, or Informed-Choice certification are generally more reliable.
- Avoid Unverified Marketing Claims – Be wary of supplements that promise rapid weight loss, appetite suppression, or metabolism boosts, as research does not support these claims. CLA offers only gradual, modest fat loss at best.
When to Consult a Healthcare Provider
Although CLA is generally safe for most people when taken within recommended doses, certain individuals should consult a healthcare provider before starting supplementation:
- People with insulin resistance, diabetes, or metabolic disorders – Some evidence suggests CLA could negatively impact glucose metabolism, so those with blood sugar concerns should seek medical advice first.
- Individuals with digestive sensitivities – CLA may cause mild gastrointestinal discomfort, including bloating and diarrhea. If you have a history of IBS or other digestive conditions, you may want to monitor your body's reaction.
- Those taking medications for inflammation or chronic conditions – Since CLA may affect inflammatory markers, it’s important to discuss potential interactions with a doctor if you’re taking medication for arthritis, autoimmune diseases, or cardiovascular conditions.
- Pregnant or breastfeeding women – There is limited research on CLA’s effects during pregnancy or lactation, so it’s best to avoid supplementation unless advised by a healthcare provider.
Conclusion
CLA may offer a small fat-loss benefit when taken consistently, but its effects are modest and slow compared to diet and exercise.
While some individuals might find it useful as a supplement, it is not a magic solution for weight loss.
If you’re considering CLA, focus on maintaining a balanced diet and active lifestyle first, and consult a healthcare provider if you have any health concerns.
