Lipo 6 Stim-Free Review

Lipo 6 Stim-Free, as the name implies, is Nutrex’s stimulant-free weight-loss formula. It features a few pretty common (but not necessarily effective) non-stimulant weight loss ingredients.

Lipo 6 Stim Free



Carnitine is an amino acid that is heavily involved with the metabolism of fat for energy. Specifically,it is required for the transport of fatty acids in the Mitochondria (“powerhouse” of the cell), where they are oxidized through the process of “beta-oxidation” for energy. Carnitine deficiency has been shown to result in hindered fat-burning capacity. Because of this integral role in the fat-burning process, Carnitine supplementation is alleged to burn-fat. However, while it has certainly been shown to normalize the fat-burning process in those who are deficient, the implications for healthy individuals are less clear.

A 2002 study, published in “Metabolism”, found that Carnitine supplementation (1g/day) increase fatty acid oxidation rates in humans without Carnitine deficiency. A 2004 study from the same journal found that L-Carnitine supplementation (3g/day) increased fatty acid oxidation in overweight subjects while having no effect on protein synthesis or breakdown.

However, a 2005 study, published in the “International Journal for Vitamin and Nutrition Research”, found that Carnitine supplementation failed to influence weight-loss in rats. The results of this study were in-line with an earlier (2002) study in which L-Carnitine supplementation (4g/day) failed to influence fat mass, body mass, or resting lipid utilization in moderately obese women.

Ultimately, Carnitine does possess the mechanisms by which it should burn fat (via increased utilization of fatty acids), though supplementation has failed to result in fat-loss in animals and humans. To be fair, the subjects in the above mentioned human study did not pair Carnitine supplementation with high intensity exercise. It is possible that the increased utilization of fatty acids seen with Carnitine supplementation may result in noticeable weight loss when paired with high-intensity exercise, but not with low-intensity exercise. This would make sense since the body would not necessarily tap into its excess availability of fatty acids unless warranted by long-duration, high-intensity exercise.

Lipo 6 Stim-Free contains 500mg Carnitine per serving which unfortunately is less than what has been shown to increase fatty acid oxidation rates in humans. It is possible that this same effect still occurs with 500mg, but this dose has not been studied.


Tyrosine is a non-essential amino acid which serves as a precursor to the neurotransmitters dopamine, norepinephrine, and epinephrine, the three of which are collectively referred to as ‘catecholamines’. A 1981 study found that subjects who consumed 100mg/kg of Tyrosine experienced a significant increase in urinary catecholamine levels (indicative of increased plasma levels), but supplemental Tyrosine has failed to produce the performance enhancing effects commonly associated with increased release of catecholamine. This is because Tyrosine does not instantly get converted into noradrenaline, dopamine, or adrenaline. It forms a pool, and when there is a deficit of these neurotransmitters, the pool is drawn from to create more. So, rather than directly increase levels of these neurotransmitters, Tyrosine effectively restores them when deficiency occurs. This deficiency occurs in times of stress, such as sleep deprivation, exposure to cold, and exercise.

Tyrosine, while not directly influencing body-weight, may support cognitive function when it would normally be impaired, such as during a restricted-calorie diet or long-duration exercise. Lipo 6 Stim-Free contains 150mg of the N-Acetyl form of Tyrosine (though to be better absorbed).


Guggulsterones have been investigated primarily in regards to thyroid function and weight loss. In rats, supplementation at about 10mg/kg has been shown to increase iodine uptake and increase thyroid function. However, no human studies have confirmed these effects. Furthermore, the dose used in these studies is much higher than what is commonly ingested in the form of herbal supplements. Lipo 6 Stim Free contains 20mg Guggulsterone per serving, far less than what has been shown to influence Thyroid function in rats, and never studied in humans.

Bioperine is a patented form of Black Pepper Extract which is generally standardized for Piperine. Several studies have found that Piperine can enhance the absorption of various nutrients when co-ingested. This enhanced absorption is due to the inhibition of certain enzymes which breakdown most compounds, as well as the slowing of intestinal transit (increasing the amount of time these compounds are exposed to the possibility of uptake). So, while Bioperine certainly doesn’t have any Testosterone boosting implications, it may enhance the efficacy of the formula in general.


Chromium is an essential mineral which plays an integral role in the regulation of blood glucose and insulin sensitivity. Several meta-analyses have been conducted to determine the potential of Chromium supplementation for weight-loss, but the results are less than encouraging. A 2012 meta-analysis concluded that Chromium supplementation had no reliable influence on body weight in diabetic subjects, despite helping to lower blood glucose. A later (2013) meta-analysis, published in the “Journal of Pharmacy & Pharmaceutical Sciences”, ultimately concluded that Chromium supplementation can potentially reduce body weight in obese/overweight humans, but the results were lackluster at best, with no more than a couple pounds being lost.

Ultimately, while Chromium may be beneficial with regards to controlling blood glucose in diabetic/overweight people, supplementation above and beyond the RDI will not result in noticeable weight-loss in the average individual.


Lipo 6 Stim Free contains a subpar blend of some alleged non-stim weight-loss agents, but the research behind most of these ingredients is very limited. It is possible that, over-time, Lipo 6 Stim Free may aid in some minor weight-loss, but this is likely to be pretty negligible compared to be what can be achieved through exercise alone. We definitely feel there are better options out there for stim-free, or low-stim, fat-burners.

Still not sure which weight-loss supplement is right for you? Check out our Top 10 Fat-Burners List!

Supplement Facts

  1. Tian, Hongliang, et al. “Chromium picolinate supplementation for overweight or obese people.” status and date: New, published in 9 (2012).
  2. Abdollahi, Mohammad, et al. “Effect of chromium on glucose and lipid profiles in patients with type 2 diabetes; a meta-analysis review of randomized trials.”Journal of Pharmacy & Pharmaceutical Sciences 16.1 (2013): 99-114.
  3. Agharanya, Julius C., Raphael Alonso, and Richard J. Wurtman. “Changes in catecholamine excretion after short-term tyrosine ingestion in normally fed human subjects.” The American journal of clinical nutrition 34.1 (1981): 82-87.
  4. Shurtleff, David, et al. “Tyrosine reverses a cold-induced working memory deficit in humans.” Pharmacology Biochemistry and Behavior 47.4 (1994): 935-941.
  5. Fernstrom, John D., and Madelyn H. Fernstrom. “Tyrosine, phenylalanine, and catecholamine synthesis and function in the brain.” The Journal of nutrition137.6 (2007): 1539S-1547S.
  6. Yeghiayan, Sylva K., et al. “Tyrosine improves behavioral and neurochemical deficits caused by cold exposure.” Physiology & behavior 72.3 (2001): 311-316.
  7. Banderet, Louis E., and Harris R. Lieberman. “Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans.” Brain research bulletin 22.4 (1989): 759-762.
  8. Wutzke, Klaus D., and Henrik Lorenz. “The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects.”Metabolism 53.8 (2004): 1002-1006
  9. Seim, H., W. Kiess, and T. Richter. “Effects of oral L-carnitine supplementation on in vivo long-chain fatty acid oxidation in healthy adults.” Metabolism 51.11 (2002): 1389-1391.
  10. Melton, S. A., et al. “L-carnitine supplementation does not promote weight loss in ovariectomized rats despite endurance exercise.” International journal for vitamin and nutrition research 75.2 (2005): 156-160.
  11. Villani, Rudolph G., et al. “L-Carnitine supplementation combined with aerobic training does not promote weight loss in moderately obese women.”International journal of sport nutrition and exercise metabolism 10.2 (2000): 199-207.
  12. Karanth, Jyothsna, and K. Jeevaratnam. “Effect of carnitine supplementation on mitochondrial enzymes in liver and skeletal muscle of rat after dietary lipid manipulation and physical activity.” (2010).
  13. Tripathi, Yamini B., O. P. Malhotra, and S. N. Tripathi. “Thyroid stimulating action of Z-guggulsterone obtained from Commiphora mukul.” Planta medica50.01 (1984): 78-80.
  14. Tripathi, Y. B., et al. “Thyroid Stimulatory Action of (< EM EMTYPE=.” Planta medica 54.04 (1988): 271-277.
  15. Badmaev, Vladimir, Muhammed Majeed, and Lakshmi Prakash. “Piperine derived from black pepper increases the plasma levels of coenzyme Q10 following oral supplementation.” The Journal of Nutritional Biochemistry 11.2 (2000): 109-113.
  16. Majeed, Muhammed, and Lakshmi Prakash. “Targeting Optimal Nutrient Absorption with Phytonutrients.” (2007) exists to educate the supplement community and seperate the science from the hype.

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