Juanita O. Enogieru MS, RD
One of the top questions I receive from clients is, “What is the best supplement for me to lose
weight?” The problem with this question is there are multiple factors involved in unwanted weight gain and varying degrees of biochemical individuality, so finding one nutrient to support everyone’s needs is impossible. However, creating a regimen of nutrients shown to promote optimal fat metabolism can assist with supporting healthy weight loss. A follow-up question that arises is, “Should I use ‘fat-burning’ supplements?” Conjugated Linoleic Acid (CLA) and L-carnitine are two options that may be considered controversial weight-loss nutrients, but research has shown that these nutrients can play a role in weight management.
What are Fat Burners?
Various supplements claim to be fat burners, but what exactly are fat burners? When I think of the name, I imagine someone taking a match to a huge chunk of fat and setting it on fire, but that’s not exactly how it works! Nutrients are considered fat burners if they increase energy expenditure, enhance fat metabolism, weaken fat absorption, increase weight loss (can include suppressing appetite), prevent weight regain after weight loss, increase fat oxidation during exercise, or promote long-term changes that encourage healthy fat metabolism.1
(Source: PMID 21951331)
Some methods that have been shown to optimize fat metabolism and may help enhance weight loss efforts include:
- Increasing (or maintaining) lean body mass 2
- Increasing insulin sensitivity (reducing insulin resistance)3
- Optimizing fatty acid beta-oxidation by encouraging fatty acid transport into the mitochondria.1
Lean body mass, often referred to as lean tissue mass and muscle mass, includes bones, ligaments, tendons, internal organs, water, and muscles. Lean body mass is associated with your basal metabolic rate (BMR), which is the number of calories burned while resting. A loss of lean body mass has multiple negative health effects, including lowered resting energy expenditure/metabolism, fatigue, a decline in neuromuscular function, and a regain in fat mass.3
Factors Affecting Fat Metabolism
Regardless of total body fat mass, it is important to note that dysfunctional adipose tissue, inflammation, and an imbalance of circulating adipokines (a type of cell-signaling proteins called cytokines that are secreted by adipose tissues) are linked to insulin resistance in obese individuals.4 During insulin resistance, a hormone derived from fat cells called adiponectin (an anti-obesity signaling molecule) can become dysfunctional. Adiponectin decreases the synthesis of fatty acids in the liver and increases β (beta)-oxidation of fatty acids.4 Insulin resistance can lead to uncontrolled glucose levels, which can impair another hormone called leptin from signaling the brain that you are full.4 Without this reminder, when there is a half a plate of food in front of you, overeating, and thus weight gain or weight regain, is inevitable. Inflammation, often measured with increased C-reactive protein (CRP) levels, can also cause leptin insensitivity.5,6 Therefore, lowering inflammation and optimizing fat cell signaling by increasing insulin sensitivity (reducing insulin resistance), is a vital aspect of any comprehensive weight-loss strategy.
Related: Boosting Serotonin for Weight Loss
If a high-calorie or calorie-dense diet is not changed, when fat oxidation decreases, the body can go into a positive energy balance, meaning that you are over the number of calories needed to maintain healthy function. Being in a positive energy balance under conditions of a high-fat diet can lead to weight gain because glycogen stores become depleted, which increases appetite and energy intake.7 Improving fat oxidation pathways can reduce the accumulation of fat. Therefore, you should help reduce fat buildup by providing the body with the tools needed to aid in transporting fatty acids into the mitochondria to be burned for cellular energy. This cellular energy is transferred throughout the body’s organs to boost healthy function.8
(Source: Int. J. Mol. Sci. 2019, 20(5), 1190)
Is Conjugated Linoleic Acid (CLA) Found in Food?
Ruminating animals (cattle, goats, sheep, deer, and bison) produce CLA via bacteria present in the first compartment of the stomach. Also, CLAs can be extracted from plant materials such as safflower and sunflower oil, but are mainly found naturally in dairy and meat products. It is vital to keep in mind that there are various forms of CLA. The c-9, t-11 (cis-9, trans-11) CLA isomer accounts for 90% of CLA in dairy products and 75% of CLA in animal meat. Plant oils have less than 50% of the c-9, t-11 CLA isomer.9 However, this biologically active form may become less active in processed dairy and meat products. The other well studied form of CLA is the t-10, c-12-isomer (trans-10, cis-12 isomer) form, which can also be found in animal products.9 This form is discussed as being the active form that affects energy metabolism and body fat deposition and composition,and may enhance the movement of glucose into muscle cells.10,11 Typically, animal products have a CLA concentration ranging from 0.34 to 1.07 g/100 g fat in milk and 0.12 to 0.68 g/100 g fat in meat, but this CLA concentration is not sufficient to meet the daily requirement (1.5 to 3.5 g/day) for human beings, or meet requirements for promoting lean body mass.9 CLA supplements often contain a mixture of the relevant isomers.
CLA and Weight Management
CLA appears to have a beneficial effect on weight management by increasing insulin sensitivity of fat cells and supporting healthier levels of lean body mass.2,10 With more individuals cutting meat products out of their diet, it certainly leaves one to wonder, what is the best way to supplement with this fatty acid and why should you try it? With all the mixed data on CLA, trying to decide if it is beneficial can be overwhelming. However, here are some of the facts:
- In a 12-week study of CLA supplementation (3000 mg daily), obese and overweight women saw a decrease in hip circumference.12
- In a randomized, double-blinded, placebo-controlled clinical trial, obese children were randomly assigned to receive metformin, CLA, or placebo for 16 weeks. After taking 500 mg of CLA six times a day (3000 mg), insulin sensitivity improved.13
- In a randomized, double-blind clinical trial, 54 adults with class I obesity were given 3000 mg of CLA (in three divided dosages) for 3 months. At the end of the trial, CLA supplementation reduced body fat mass and percentage, as well as serum leptin levels. Fasting glucose and insulin resistance also declined during the 3-month intervention.14
- 12 weeks of CLA supplementation (3.2 or 6.4 grams/day) reduced body fat mass, body fat percentage, measures of insulin resistance (and fasting blood sugar), as well as serum leptin levels, in 48 obese adults. However, those in the 6.4 g/day group experienced body weight gain, possibly due to increased lean body mass.15
- Reviews and meta-analyses appear to indicate that CLA can confer modest loss of body fat in people.16
- From a 2019 review: “The literature to date suggests that CLA, and primarily the 10,12 CLA isomer, consistently confers some degree of body weight and/or adiposity loss in animal models and humans. However, such effects on body energetics may not impart protection against obesity-associated comorbidities, such as type 2 diabetes.”17
Is CLA Supplementation Bad for My Liver?
Adverse effects are very unlikely at suggested dosages with raw materials that contain mixed isomers. Although some data suggests negative liver effects may occur from isolated administration of the t-10, c-12 CLA isomer, these are mostly based on animal studies using extremely high dosages.18 These dosages are exceptionally higher than the typical therapeutic dosage for humans (approximately 3 grams). Clinical studies using ~3 grams/day of the mixed isomers have generally not reported any significant safety issues or adverse effects.19
Nutrient Synergy: Enhancing CLA’s Effects with Sesame
Since CLA is a fatty acid, to fully reap its benefits, find a product that combines it with sesame lignans. Preclinical research suggests that sesame lignans may enhance the body fat-reducing effects of CLA.20 Additionally, sesame lignans may further increase the burning of fat by stimulating fatty acid oxidation in the liver. Sesamin, an abundant lignan in sesame seeds, was shown to stimulate fatty acid beta-oxidation in the liver and reduce serum cholesterol in a preclinical model.20
What is the Recommended Dose of CLA?
To encourage the best possible outcome, select a supplement whose raw material contains both the trans-10, cis-12 isomer, and cis-9, trans-11. The exact amount of each may be variable but look for a raw material where each is typically present at 37.5-42% of the total amount of CLA. As far as dosage is concerned, at least 3-4 g (3000-4000 mg) of CLA should be utilized to promote healthy fat metabolism; however, the latter may support reductions in glucose and improvements in insulin sensitivity.11 Furthermore, one study suggests a daily intake of 5-10 g of CLA for diabetic therapy.21
Synergy is the interaction of nutrients that lead to a combined effect that is better than the effect of the nutrients alone. Some studies suggest that combining CLA with synergistic nutrients can promote healthier outcomes.10 To encourage healthier results, CLA should be paired with nutrients that promote healthy carbohydrate metabolism, specifically insulin metabolism, such as L-carnitine.
What is L-Carnitine?
L-carnitine is an amino acid that is involved in long-chain fatty acid and carbohydrate metabolism—it is required to transport the fatty acid into the cell where it is used to make ATP (adenosine triphosphate), or cellular energy.22 L-carnitine is made inside the body from lysine and methionine and can also be obtained mainly from animal sources. Dietary lipids require carnitine in order to be used as a source of energy. However, there is a theory that with high enough dosages of carnitine, levels build up in muscle cells to increase energy production and build muscle. This may be the wrong way to understand the value of L-carnitine. Instead, it may be best to use carnitine to boost mitochondrial function by fostering the transportation of long-chain fatty acids into the mitochondria.
While some resources imply that carnitine has no benefits for weight loss, at appropriate dosages, L-carnitine consistently confers weight loss benefits for overweight/obese adults.23 The effects would be enhanced with a balanced plant-based diet. A 2020 review and dose-response meta-analysis of 43 clinical studies concluded that L-carnitine decreased body weight, BMI, and fat mass.24 L-carnitine can also be helpful for managing insulin resistance.25 This, amongst other metabolic actions, makes L-carnitine an ideal companion for CLA!
What is the Recommended Dose of L-Carnitine?
Although a meta-analysis of carnitine supplementation concluded that L-carnitine might be effective for weight loss in adults, the dosage that best supports this varies. Dosages analyzed in this study ranged from 2-4 g (2000-4000 mg) daily.
How to Supplement with CLA and L-Carnitine
CLA may be helpful to aid in improving body composition. Its impact on insulin resistance is still unclear, so combining it with L-carnitine is likely beneficial to help weight loss and improve insulin sensitivity.
Start with the lower dosages for one week, or 1000 mg of CLA and 1000 mg of L-carnitine, and note your tolerance and sensitivity. If well tolerated, increase the dosage after week one to 2000 mg of CLA and 2000 mg of L-carnitine. In the third week, you can increase your dosage to 3000 mg of CLA and maintain the 2000 mg of L-carnitine dosage. Over the next few weeks, monitor your responses, and if you feel it is valuable, you can try increasing the dosage of CLA to 4000 mg, and experiment with boosting L-carnitine to 3000-4000 mg. Most importantly, keep in mind that any weight loss supplement regimen should be discussed with a doctor and combined with a healthy lifestyle, which includes monitoring blood work annually.
The Bottom Line
We continuously see that the body thrives on a variety of nutrients to achieve and maintain optimal health. Although most people are looking for one supplement to meet all their health goal needs, it is more likely that more than one nutrient or supplement with comprehensive nutrient profiles are required to achieve weight loss and promote weight loss management. Using multiple quality supplements formulated based on science is safe and provides the body with the tools needed to support healthy function while also promoting weight loss.
A combination of nutrients is more likely to offer the best outcome than one alone. So, combining CLA and L-carnitine, as well as other supportive nutrients like Gynostemma pentaphyllum and green tea extracts, may be ideal for addressing the underlying pathways needed to enhance weight loss and maintain lean body mass.1
About the author: Juanita Enogieru is a Registered Dietitian and Life Extension Wellness Specialist working with the community to build healthy and balanced nutritional habits. While pursuing an education in medicine and attempting to help her body heal, it became apparent that there was a gap in medical practices with regard to nutrition and an abundance of misinformation about balanced nutritional practices. After obtaining a bachelor’s degree in Health Education from the University of Florida, she worked with non-profit organizations to deliver nutrition education to community members. Wanting to learn more about nutrition and how herbs could be used to help the body heal, she pursued a master’s degree in Dietetics and Nutrition and shortly after began working with Life Extension. With the understanding that everyone has a unique biochemical individuality, it is vital to address each individual based on their specific needs and biochemical make-up. Her mission now is to offer guidance, support and education to individuals based on balanced nutritional insights that address the mind, body and spirit.
- Obes Rev. 2011 Oct;12(10):841-51.
- Adv Clin Exp Med. 2017;26(2):333-338.
- Nutrients. 2018 Dec; 10(12): 1876.
- Cell Metabolism. 2016 May 16; 23(5): 770-784.
- Nat Med. 2006 Apr;12(4):425-32.
- Curr Pharm Des. 2014;20(4):609–615.
- Obes Rev. 2011 Oct;12(10):859-65.
- Food Chem Toxicol. 2019 Jan;123:205-224.
- Med Hypotheses. 2000 Mar;54(3):483-7.
- Med Sci Sports Exerc. 2004 May;36(5):814-20.
- Acta Sci Pol Technol Aliment. 2016 Jan-Mar;15(1):107-113.
- J Clin Endocrinol Metab. 2017 Jan 1;102(1):132-140.
- Arch Iran Med. 2019;22(5): 255-261.
- J Nut. 2007 May;137(5);1188–1193.
- Am J Clin Nutr. 2007 May;85(5):1203-11.
- Nutrients. 2019 Feb 11;11(2). pii: E370.
- Am J Clin Nutr. 2004 Jun;79(6):1153S-1158S.
- Biosci Biotechnol Biochem. 2001 Nov;65(11):2535-41.
- Med Hypotheses. 2000 Mar;54(3):483-7.
- Nutr Metab (Lond). 2010 Apr 16;7:30.
- Obes Rev. 2016 Oct;17(10):970-6.
- Pharmacol Res. 2020 Jan;151:104554.
- Adv Clin Exp Med. 2017;26(2):333-338.