Do a quick internet search for CLA before and after pics, and you'll find countless photos of men and women who have seemingly lost weight and toned up by consuming conjugated linoleic acids, a type of fatty acid found primarily in dairy products and beef.
Sold as a health supplement, conjugated linoleic acids — also known as CLA — has been hailed as a way to lose weight, reduce cholesterol and even beat cancer. As great as this sounds, there's little scientific evidence to support these claims.
CLA plays an important role in fat metabolism, according to a September 2015 review published in the Journal of the International Society of Sports Nutrition, but the facts show that the claims about it may be a little inflated.
What Is CLA?
CLA is a chain of fatty acids that are produced in the digestive tracts of ruminant mammals: Animals that ruminate their plant diet in a special stomach before it undergoes full digestion. Ruminant animals include cows, goats, sheep and buffalo, as well as pigs, chickens and turkeys.
When consumed by humans through eating meat or dairy, CLA increases lipolysis (the breakdown of stored energy in the form of body fat), reduces lipogenesis (the conversion of energy to body fat) and promotes apoptosis (the death of cells) in adipose tissue. In simpler terms, CLA could help you burn fat and stop your body from burning fat.
Because of this, CLA has been categorized as a functional food, meaning that its health effects extend beyond nutritive value of calories and macro-nutrients. In the case of CLA, it has been hailed as being able to positively influence body composition, cardiovascular health, immunity, asthma, cancer and diabetes. CLA is commercially available in the United States under the trade names CLA-80 and Tonalin.
Does It Work?
Although CLA is marketed as a weight-loss product in CLA before and after pictures, studies show mixed results, according to the Memorial Sloan Kettering Cancer Center.
A September 2015 review in the Journal of the International Society of Sports Nutrition looked at 16 randomized clinical trials (all of which involved between 14 and 401 human subjects between the years 2010 and 2015) and noted that nine of those trials showed no benefits related to CLA — no effect on platelet function, no physical training improvements, no reduction of cholesterol levels, no effect on waist circumference, no effect on glucose metabolism or insulin sensitivity, and so forth.
However, these trials did show CLA could be effective in reducing inflammatory markers in rheumatoid arthritis patients and in reducing tumor invasion and resistance to cancer treatment in patients with rectal cancer. Overall, supplementing your diet with CLA doesn't makes a big difference in your overall health, especially in terms of fitness and weight loss, but it could help reduce symptoms of a few specific diseases.
In many cases, changes in weight and body composition happen when CLA is combined with exercise programs. For example, a March 2013 study published in Chemico-Biological Interactions involved 18 sedentary male volunteers who were divided into two groups: One took CLA and the other took placebos for 30 days while they exercised three times a week. This study concluded CLA to be no more effective than exercise alone.
Another study, also from 2013, this one published in November in Hospitalaria Nutrition, looked at 38 volunteers who consumed 200 milliliters of skim milk with either 3 grams of CLA or 3 grams of olive oil as a placebo daily over the course of 24 weeks. In this case, subjects lost body weight and fat mass, but this was combined with habitual diet and exercise practices.
Some athletes turn to CLA as a way to increase muscle mass and strength gained from heavy resistance training. A February 2015 review published in Nutrition and Metabolism points out that short- and long-term studies using high doses of CLA have benefits in that they not only reduce fat mass but also increase lean body mass.
The review in Journal of the International Society of Sports Nutrition noted that few studies looked at CLA apart from physical activity, which concludes that it's benefits for improved body composition were "discordant," "insufficient" and "not unanimous."
How to Take It
Most of the reports on CLA show it to be safe for daily consumption. The National Institutes of Health Office of Dietary Supplements lists few safety concerns when taken in doses of 2.4 to 6 grams of CLA a day for up to 12 months.
None of the studies included in a February 2015 review published in Nutrition & Metabolism emphasized a specific time of day when subjects took CLA, but most of them were administered a daily dose.
For those who struggle with nausea, it might be worth finding a time when side effects are minimal. Cleveland Clinic advises that taking dietary supplements on an empty stomach can make you feel sick and that taking supplements right before exercise will increase gastric acid production.
Special Considerations for CLA
As with any dietary supplement, CLA could pose risks for people with specific health problems. You should not take CLA if you:
- Have metabolic syndrome.
- Are taking blood-thinning drugs.
- Have diabetes, as CLA has caused insulin resistance and may increase blood glucose levels.
- Have heart disease or are at risk for cardiovascular complications, as it may increase processes that cause cell damage.
CLA Before and After
The before and after shots of people who use CLA may indeed be authentic, but it's likely that CLA is not the only change they have made to their lives. Even if people include CLA in successful weight loss plans, its effects are insignificant and of questionable relevance. Reviews of the many studies in human subjects conclude that more research is needed to determine its efficacy and safety.
Experts on weight management agree that instead of turning to weight-loss supplements, people should adopt new habits and make lifestyle changes — such as a healthy diet full of nutrient-dense, low-calorie foods, combined with increased physical activity — to achieve long-term, sustainable healthy body composition.
Furthermore, weight-loss supplements are expensive, and some ingredients can interfere with medications. A doctor can offer insight into whether a weight-loss supplement or medication is the right choice for you.
For healthy weight loss, Mayo Clinic encourages a diet full of fruits, vegetables, grains, low-fat dairy, lean protein and nuts, as well as at least 150 minutes of moderate physical activity a week or 75 minutes of vigorous aerobic activity.
- National Institutes of Health Office of Dietary Supplements: "Dietary Supplements for Weight Loss"
- Journal of the International Society of Sports Nutrition: "A Review on Effects of Conjugated Linoleic Fatty Acid (CLA) Upon Body Composition and Energetic Metabolism"
- Nutrition & Metabolism: "Pros and Cons of CLA Consumption: An Insight From Clinical Evidences"
- Memorial Sloan Kettering Cancer Center: "Conjugated Linoleic Acid"
- Chemico-Biological Interactions: "Effects of conjugated Linoleic Acid Supplementation and Exercise"
- Hospitalaria Nutrition: "Effects of Milk Supplementation With Conjugated Linoleic Acid"
- Cleveland Clinic: "Get Nauseous After Taking Vitamins? 6 Tips to Make Them Easier to Stomach"
- Mayo Clinic: "Weight-Loss Basics"