Eating a diet rich in healthy fats can do wonders for your health. Good fats, or monounsaturated and polyunsaturated fats, have been proven to boost immunity, lower cholesterol, and reduce the risk of heart disease. They also help satiate you, keeping you from feeling hangry, which is a major bonus when you need fuel in stressful times.
But can good fats actually help you lose weight? The latest buzz around conjugated linoleic acids, or supplements containing CLA oils, touts these as fat burners that will help you shed pounds. But what do experts have to say? Ultimately, they agree: It's best to avoid CLA supplements and ingest the fats as they naturally occur in foods. And while it's ideal to consult with a dietitian if you are looking to lose weight, if that isn't feasible, your best course of action is cutting back calories and consuming balanced, nutrient-rich foods.
Ahead, we tap two dietitians and a nutritionist on the purported efficacy of CLA for weight loss.
What are conjugated linoleic acids (CLAs)?
Conjugated linoleic acids are double-bonded polyunsaturated fats that are naturally found in the milk and meat of ruminating animals, like cows, goats, sheep and deer. They are marketed as dietary supplements.
In investigating the fat-burning potential of CLA fats, it's important to look at two studies to frame recent buzz: According to a 2010 review, CLA fats can reduce body fat in animals, however, its effects on humans is less clear. A 2020 study also had mixed indications, with results suggesting that CLA fats can have anti-obesity and anti-diabetic effects. However, this study was also conducted on animals. As such, research indicates CLA fats may regulate the expenditure of energy, however it remains to be seen if CLA fats can actually speed up the human metabolism. Let's see what our experts have to say.
Meet the Expert
Tony Castillo, MS, RDN, LDN is a nutritionist with expertise in sports medicine and sustained weight loss and is the co-founder of Nutrition for Performance.
Serena Poon, CN, CHC, CHN is a chef, nutritionist, and reiki master, and founder of the method of Culinary Alchemy®, which is a combination of education, integrative and functional nutrition, and healing energy.
Lisa Richards, CNC is a nutritionist and author of The Candida Diet, with expertise in gut health and inflammation.
How Healthy Fats Can Help You Lose Weight
According to Richards, there are four primary forms of fat: saturated, monounsaturated, polyunsaturated, and trans fat. "These fats differ on a molecular level and impact our health in positive and negative ways," says Richards. "Saturated and trans fats are considered unhealthy fats and are typically solid at room temperature, while trans fat can be found liquid at room temperature as well. These unhealthy fats earn this name by causing an increase in bad cholesterol and inflammation which can lead to heart disease among other chronic diseases."
Healthy fats, on the other hand (monounsaturated and polyunsaturated) are liquid at room temperature and are considered healthy for two reasons: "First, they do not increase the likelihood of heart disease or inflammation leading to chronic diseases, primarily due to their liquid form and molecular state," says Richards. "Second, they can actually improve cardiovascular health and inflammation in the body." Some examples of foods with healthy fats include salmon, sardines, trout, herring, avocado, olive oil, nuts, flax, tofu, and sunflower seed oil.
"A diet full of healthy fats is simultaneously full of beneficial nutrients that will help boost weight loss. Conversely, by avoiding foods with bad fat, you are also eliminating many junk foods and high-calorie, low-nutrient foods from your diet that only lead to weight gain and inflammation," explains Richards.
Castillo adds that healthy fats have other functions in the body, helping it to absorb vitamins A, D, E, and K. "They boost our immune system, regulate body temperature, create the feeling of satiety, and regulate hormones," he says.
Poon notes polyunsaturated fats are considered essential fats. "We need these for health and must consume from food. Omega-3 and omega-6 fatty acids and CLAs are polyunsaturated fats."
How CLAs Work
As aforementioned, polyunsaturated fats like CLAs are beneficial to your diet for a couple of reasons, including keeping you sated. Castillo points out, "These fats can help you lose weight because they help keep you fuller longer, which could mean less late-night snacking.”
The molecular composition of CLA fats is also a factor in weight loss, as indicated from previous studies. "CLA oil is supposed to increase the number of enzymes that are involved in breaking down fat,” says Castillo, which is supported by reviews such as one published in 2015 that references the metabolic function of CLAs. Poon calls these studies "promising," adding that "studies in animals show CLA may decrease energy intake, increase energy expenditure, and inhibit the production of formation of fat cells, aiding in weight loss," she explains, though, she forewarns, "Human studies have had mixed results.”
Richards also notes that research points to the efficacy of CLA oil to break down fats in animals at a high speed. "This leads to the concept that CLA can improve weight loss by increasing fat burning in the human body as well," she says. However, she also points out that "human studies have not been as effective at proving this claim."
Known Side Effects of CLAs
One of the major drawbacks of CLA fats is that there is a potential for increased inflammation, a condition that not only is associated with weight gain, but other health hazards as well. "By increasing the food sources of CLA, you are simultaneously increasing saturated fat in your diet, which can lead to increased risk of cardiovascular disease and other chronic diseases," says Richards. "Supplementing with CLA can lead to chronic inflammation."
Castillo notes that CLA can "increase C-reactive protein," which is associated with inflammation and liver damage.
Poon also warns that consuming too much CLA may "slow blood clotting, and may lead to an accumulation of fat in the liver."
How to Use CLAs Safely
In weighing the pros and cons of consuming CLAs for fat-burning potential, Poon advises people to limit their dosage: "3.4-6.8g per day has been found to be effective for weight loss in overweight or obese people." For people who are not overweight or obese, it's best to discuss with your doctor or nutritionist whether you should add CLA fats to your diet if you want to lose weight.
Finally, all our experts agree that it's best to avoid CLA supplements and ingest the fats as they naturally occur in foods. "Generally, I would recommend that people get their CLA from food, specifically grass-fed animals, instead of the supplement form," says Poon. "CLA supplements are made from chemically altered vegetable oil."
Does Safflower Oil Contain CLA?
The notion of taking safflower oil for weight loss became popular through the weight loss company SafSlim, which claimed that its high-linoleic safflower oil would help reduce belly fat; this could in turn confuse consumers into thinking the oil contains a substantial amount of CLA.
However, safflower oil may contain as little as 0.7 mg CLA per gram fat. Even more confusing is that supplements labeled "CLA safflower oil" are a result of chemical processes which convert the linoleic acid in safflower oil into a form of CLA, but this is all done in a lab and not the result of safflower oil having high natural CLA content.
"While I do acknowledge that CLA has been effective for some for weight loss, I would consider it preferential," says Poon. In other words, as previously mentioned, those who are overweight or obese have seen the greatest results from adding a limited dosage of CLAs to their diet.
Also, don't assume that promising clinical trials on animals necessarily makes CLA a panacea for achieving and maintaining a healthy weight.
"I would recommend working with a dietitian," says Castillo. "If this is not something you can do at this time, then monitor your intake for a week and see where you can make changes.”
Indeed, the bottom line reinforces the basics of weight loss we all know by now. "I recommend improving your weight loss by consuming a balanced diet focused on anti-inflammatory foods that are rich in nutrients and low in calories," says Richards.
Harvard Health Publishing. The Truth About Fats: The Good, the Bad, and The In-between. Updated December 11, 2019.
Kennedy A, Martinez K, Schmidt S, Mandrup S, LaPoint K, McIntosh M. Antiobesity Mechanisms of Action of Conjugated Linoleic Acid. J Nutr Biochem. 2010;21(3):171-179. doi:10.1016/j.jnutbio.2009.08.003
Trinchese G, Cavaliere G, Cimmino F, et al. Decreased Metabolic Flexibility in Skeletal Muscle of Rat Fed with a High-fat Diet Is Recovered by Individual CLA Isomer Supplementation Via Converging Protective Mechanisms. Cells. 2020;9(4):823. doi:10.3390/cells9040823
Lehnen TE, da Silva MR, Camacho A, Marcadenti A, Lehnen AM. A Review on Effects of Conjugated Linoleic Fatty Acid (CLA) Upon Body Composition and Energetic Metabolism. J Int Soc Sports Nutr. 2015;12:36. doi:10.1186/s12970-015-0097-4