Does L-Tyrosine Help With Weight Loss?

Weight loss is hard. Weight loss maintenance is even harder. We always talk about the need to not give up when we go off track. But you have to admit that the more the slip ups, the greater the loss of morale and deterioration in your self-belief to lose weight. 

Weight loss supplements are designed to speed up fat loss and have you attain weight reduction quicker. How successful these supplements are will depend on what they are made of. A few fat burners have started to include l-tyrosine as an ingredient. But does it actually aid weight loss? That should not be too hard to figure out if we delve into the science. Keep reading.

key findings

  • L-tyrosine has a robust history of use as a cognitive enhancer but hardly any as a weight loss aid.
  • The evidence around l-tyrosine’s weight loss abilities is weak.
  • Its inclusion in weight loss supplements is likely due to its ability to boost mood and motivation, something that is much needed given how difficult weight loss can be.

What is L-Tyrosine

L-tyrosine is a nonessential amino acid. Nonessential meaning it’s an amino acid that the body produces on its own. It also occurs in food such as cheese, milk, fish, chicken, soy, peanuts and avocado. L-tyrosine has been shown to play important roles in the production of key neurotransmitters (i.e. brain chemicals) including dopamine, norepinephrine and epinephrine. This ability to influence cognitive function, mood and sleep quality has seen it widely used in nootropic products

Apart from cognitive benefits, l-tyrosine has other proven abilities such as melanin production and the normal function of thyroid, pituitary and adrenal glands. Until relatively recently, you did not hear this amino acid mentioned in the context of weight loss. It’s happening and products that contain swear that it works. We’ll take a look at the conclusion that key scientific studies have come to.

L-Tyrosine and Weight Loss

The Case For

I’ll start off with a 2001 study that examined the effect of l-tyrosine on behavior, exercise endurance and brain chemistry in mice. The mice were fed on a restricted diet over a two-week period. In the second week, they were injected with l-tyrosine or saline and then exercised on a wheel. The restricted diet led to a sharp weight loss and decreased food consumption. 

However, mice introduced to l-tyrosine in the second week saw restoration of food consumption but without a subsequent increase in weight since there was a substantial increase in activity. The group on saline had a reduction in physical activity. Overall, the study showed l-tyrosine may improve food consumption, activity performance, exercise tolerance as well as delay the onset of fatigue.

In the same year, a separate study on mice found that l-tyrosine may aid weight loss maintenance and the treatment of obesity.

Turning to research involving human subjects, a very limited study in 2016 observed five persons diagnosed with nemaline myopathy and placed on l-tyrosine supplementation. Participants demonstrated improvements in energy levels, exercise tolerance and strength. But we can hardly draw substantial conclusions from such narrow research.

The Case Against

A human study published in 2005 placed doubt on l-tyrosine’s ability to substantially contribute to weight loss. Specifically, its impact on activity, endurance and delayed fatigue. 20 men facing serious physiological stress were placed on a placebo or 150 mg per kg l-tyrosine then subjected to treadmill sessions. It found no difference in endurance and muscle strength between the placebo and l-tyrosine groups.

Worse still, an extensive 2017 review on the levels of various amino acids and its correlation to weight found l-tyrosine among those whose increase coincided with obesity and decrease with weight loss.

Dosage and Side Effects

Ideal doses of l-tyrosine will vary from person to person. Taking 150 mg/kg to 300 mg/kg per day has been proven safe when taken with the intention to boost exercise capacity. Fat burners containing l-tyrosine have it at a daily serving of 300 mg give or take. 

L-tyrosine supplementation is not recommended for persons diagnosed with (or on medication for) depression, abnormal blood pressure or thyroid problems except with a doctor’s consent.

Wrapping Up

The evidence on l-tyrosine’s weight loss abilities is extremely weak. In fact, the few weight loss supplements that contain l-tyrosine clarify its inclusion is less to do with weight reduction and more to do with improving mood and motivation. The rationale here appears to be that improved mood can help you follow through on your weight loss goals. Not actually a bad thing. But definitely does not position l-tyrosine as a true weight loss aid.

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About the Author

Sam is a passionate health and fitness enthusiast who has been interested in supplements, fitness, and wellness for over 10 years. He is the founder of Great Green Wall - the health and wellness brand and has completed multiple fitness certificates, including personal training and nutrition certifications. Sam has been working as a personal trainer for the past three years and is dedicated to helping his clients achieve their fitness goals and lead healthier lifestyles. He believes that a healthy lifestyle is crucial to a happy and fulfilling life and is committed to sharing his knowledge and passion with others.

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