All fats are not created equal.
Some are used to provide energy while others can have powerful effects on your health.
Conjugated Linoleic Acid (CLA), a fatty acid that can be found in meat or dairy, is thought to have many health benefits (1).
It’s also a popular weight-loss supplement (2).
This article will examine the effects of CLA on weight and overall health.
Linoleic acid is the most commonly found omega-6 fatty acids. It can be found in large quantities in vegetable oils, but also in small amounts in other foods.
The prefix “conjugated”, refers to the arrangement of double bonds within the fatty acid molecule.
There are 28 forms of CLA (3).
These forms differ in that the double bonds they have are different. Remember that even something so small can make a huge difference in our cells.
CLA is basically a type polyunsaturated, Omega-6 fatty acid. It is technically a trans-fat, but it is a natural trans fat found in many healthy foods (4).
Numerous studies have shown that high levels of industrial trans fats, which differ from natural trans fats such as CLA, can cause health problems (5-6-7).
> Summary CLA refers to a type of omega-6 fat acid. Although technically it’s a trans fat, CLA is very different from industrial trans fats which can be harmful to your health.
CLA is found in the meat and milk of ruminants such as sheep, goats, and cows.
The amount of CLA found in these foods will vary depending on the animal’s diet (8).
CLA is found in beef, and dairy from grass-fed cows, 300-500% more than it is in grain-fed cows (9).
Many people consume some CLA from their diets. In the US, the average daily intake is 151 mg for women and 212 for men (10).
Remember that CLA found in supplements is not made from natural foods, but chemically altered linoleic acids found in vegetable oils (11).
Supplements can greatly alter the balance of these different forms. These supplements contain CLA types that are not found in nature (12, 13, 13).
CLA supplements don’t have the same health benefits as CLA found in foods.
> Summary CLA supplements can be obtained by chemically altering vegetable oil.
Researchers discovered CLA’s biological activity in mice when they noticed it could fight cancer (14).
Other researchers later discovered that it could also lower body fat (15).
CLA was discovered to be a possible weight loss solution as obesity rose worldwide.
CLA is one of the most studied weight loss supplements in the world.
Studies on animals suggest that CLA could reduce body fat in a variety of ways (16).
It was shown to decrease food intake, increase fat burn, stimulate fat metabolism, inhibit fat production, and reduce food intake in mouse studies (17, 18, 19, 20, 20).
CLA has been extensively studied in randomized controlled experiments, which are the gold standard for scientific experimentation on humans. However, mixed results have been obtained.
CLA may be able to cause significant fat loss, according to some studies. CLA may also help improve body composition by decreasing body fat and increasing muscle mass (21-22 23, 24, 25, 25).
Many studies, however, show no effect (26, 27, 28, 28).
A review of 18 controlled trials revealed that CLA caused modest fat loss (29).
These effects are strongest in the first six months. After that, fat loss plateaus for as long as two years.
This graph illustrates how weight loss slows over time.
This paper shows that CLA can result in a fat loss of approximately 0.2 pounds per week (01. kg) for approximately six months.
Another study found that CLA resulted in weight loss of about 3 pounds (1.3kg) more than placebo (30).
These weight loss effects are statistically significant but they are not large enough to cause side effects.
> Summary Although CLA supplements can be linked to fat loss, they are not reliable and are unlikely to make any significant difference in daily life.
CLA can be found mostly in ruminant meats and dairy.
Long-term observational studies have shown that CLA consumption is associated with increased risk of developing diseases.
People who consume a lot CLA from food are less likely to develop type 2 diabetes (31, 32 and 33).
Studies in countries with a high proportion of grass-fed cows have shown that those who have the highest levels of CLA in their bodies are at lower risk for heart disease (34).
This lower risk could be due to other protective ingredients in grass-fed animal products such as vitamin K2.
Grass-fed beef and dairy products are also healthy for many other reasons.
> Summary There are many studies that show that those who consume the most CLA have a better metabolic health and a lower chance of developing many diseases.
There is evidence to suggest that small amounts of natural CLA can be beneficial in foods.
The chemical modification of linoleic acids from vegetable oils creates the CLA found within supplements. They can be found in a different form to the CLA naturally found in food.
Supplemental doses can also be much higher than those from milk or meat.
Some nutrients and molecules can be beneficial in small amounts, but they can also cause harm if taken in large quantities.
CLA supplements have been shown to be effective in this regard according to studies.
Supplemental CLA in large doses can lead to liver fat accumulation, which is a step towards metabolic syndrome or diabetes (35, 36 and 37).
Numerous studies on animals and humans have shown that CLA can cause inflammation, insulin resistance, and lower “good” HDL cholesterol (38 and 39).
Remember that the doses used in many animal studies were much higher than what you get from supplements.
Some human studies with moderate doses of CLA supplement have shown that they can cause diarrhea, insulin resistance, and oxidative stress (40).
> Summary CLA found in supplements differs from CLA found naturally within foods. Numerous animal studies have shown that CLA can cause liver damage and other side effects.
The majority of studies on CLA used doses between 3.2 and 6.4 grams per day.
A review found that weight loss requires a minimum of 3g daily (40).
People are safe with doses up to 6 grams daily. There have been no reports of adverse side effects (41, 42).
CLA can be added to food by FDA and is given a GRAS status (generally considered safe).
Keep in mind, however, that side effects can increase as you take more of the medication.
> Summary CLA studies have been conducted at doses ranging from 3.2 to 6.4 grams per day. While evidence suggests that it does not cause serious adverse effects when taken up to 6 grams daily, higher doses can increase the risk.
Research suggests that CLA only has a modest effect on weight loss.
It doesn’t cause any side effects when taken up to 6 grams daily, but there are concerns about the long-term effects on your health if you take supplemental doses.
It may not be worth losing a few extra pounds, especially when there are other ways to do so.
