How much L-tyrosine do you need to take to lose weight?

L-tyrosine (also known as tyrosine) is one of the 20 amino acids your body needs to function. It’s a nonessential amino acid, which means your body can produce it from phenylalanine, another amino acid. Tyrosine has several vital functions in your body. It helps produce the neurotransmitters dopamine, epinephrine, and norepinephrine; contributes to melanin production, the pigment that gives color to skin and hair; and supports your adrenal, pituitary, and thyroid glands in hormone production. On top of all that, L-tyrosine has gained attention for its potential as a weight-loss aid. “Because L-tyrosine is used to make thyroid hormones, it’s believed that supplementation of this amino acid can affect metabolism and help with weight loss,” says Jeanette Giacinto, a registered dietitian based in Long Beach, New York. Most supplement manufacturers recommend 500 to 1500 mg daily, but specific dosing can vary.

How much L-tyrosine should you take for weight loss?

Studies have found that L-tyrosine doses of 100-200 milligrams per kilogram of body weight are safe for up to three months. That means a 150 lb (68 kg) person can take 6,800 mg to 10,200 mg—or about seven to 10 grams daily, says Giacinto. However, most manufacturers recommend a total dosage of 500 mg to 1,500 mg daily.

L-tyrosine is generally recognized as safe by the U.S. Food and Drug Administration (FDA), but it’s important to note—there is no standard recommended dosage of L-tyrosine for weight loss. It differs by weight, age, and individual tolerance, says Christina Rahm, Ph.D., a nutraceutical researcher based in Tennessee.

L-tyrosine can start working within 30 minutes to a few hours after ingestion, but individual responses may vary. While L-tyrosine becomes available to the body and starts working immediately, it takes a few weeks to notice its effects, adds Giacinto.

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When should you take L-tyrosine for weight loss?

“Taking L-tyrosine before meals may reduce appetite,” says Giacinto. She recommends taking three daily doses, one before each meal. For example, if your total daily dose is 1,500 mg, you’d take one 500 mg dose 30 minutes before eating breakfast, lunch, and dinner.

Taking L-tyrosine on an empty stomach may also allow for better absorption, says Umo Callins, RD, a registered dietitian at Well Rooted Health and Nutrition in Oklahoma City. Combining L-tyrosine with vitamin B6, B9 (folate), and copper may help the body convert the amino acid into important neurotransmitters. 

Check in with a pharmacist or healthcare provider before combining L-tyrosine with other supplements. “Stacking L-tyrosine with other supplements should be done under the guidance of a healthcare professional,” says Rahm.

Benefits of L-tyrosine

Proponents of L-tyrosine say it can help you lose a few pounds, enhance cognitive function, make you feel more alert, and more. While more research on L-tyrosine’s health benefits is needed, some studies back up these claims.

1. Supports weight loss

One study found that people taking a supplement containing L-tyrosine, capsaicin, catechins, and caffeine lost more weight than those taking a placebo. It’s thought that L-tyrosine can speed up your metabolism, says Giacinto. However, more evidence is needed to confirm its efficacy as a weight-loss supplement.

2. Enhances mental performance

Some research shows that L-tyrosine supplementation can boost mental performance—helping to reduce “brain fog” in high-stress conditions and prevent cognitive decline. During periods of high stress, depletion of neurotransmitters (such as dopamine and or norepinephrine) often occurs, explains Callins. L-tyrosine increases these neurotransmitters, helping to counteract the mental effects of stress.

“L-tyrosine, as a precursor to neurotransmitters like dopamine, norepinephrine, and epinephrine, is implicated in supporting mental health by potentially reducing stress and contributing to mood regulation,” says Rahm. However, more research is needed to support its use for this purpose.

3. Increases energy

“L-tyrosine is associated with increased energy levels by supporting the synthesis of neurotransmitters like dopamine and norepinephrine,” says Rahm. Dopamine helps regulate energy levels (too little can cause fatigue), and norepinephrine helps break down fat and convert sugar to energy.

While studies on L-tyrosine supplementation as a standalone energy booster are limited, evidence supports that L-tyrosine, in combination with caffeine and other amino acids, can improve mental performance and exercise tolerance in athletes. “Many energy-promoting drinks and powders contain this combination as part of their formulation,” says Callins.

4. May help with phenylketonuria (PKU)

Phenylketonuria (PKU) is an extremely rare inherited disorder that increases blood levels of phenylalanine, an amino acid found in protein-containing foods like meat, eggs, dairy products, and nuts. Your body uses phenylalanine to produce L-tyrosine. Individuals with PKU must avoid foods containing phenylalanine, which can result in a deficiency of L-tyrosine.

L-tyrosine supplementation in individuals with PKU has been suggested, but research does not strongly support its use. Larger-scale studies are necessary to establish the benefits of L-tyrosine supplements for those with PKU.

5. Supports thyroid health and a healthy metabolism

“L-tyrosine is vital for supporting thyroid health by playing a key role in the synthesis of thyroid hormones—thyroxine (T4) and triiodothyronine (T3)—crucial for regulating metabolism and promoting healthy metabolic function,” says Rahm.

An older study found that L-tyrosine supplementation improved thyroid function among individuals living in Antarctica during the winter. This suggests that L-tyrosine may be beneficial in situations involving underproduction or disrupted production of thyroid hormones, says Callins. However, she says it’s vital to speak with a medical professional before supplementing with L-tyrosine for thyroid health.

 
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L-tyrosine side effects

According to Giacinto, you may experience the following side effects of L-tyrosine supplementation:

• Headache 
• Fatigue
• Nausea
• Heartburn
• Joint pain
• Insomnia

While L-tyrosine is considered safe for most individuals to take every day for up to three months, certain individuals should avoid the amino acid. They include:

• People with hyperthyroidism (overactive thyroid) or Grave’s disease
• Patients with hypothyroidism (underactive thyroid) who are taking Synthroid (levothyroxine)
• Individuals with melanoma
• Patients taking a class of antidepressants known as monoamine oxidase inhibitors (MAOIs), such as Marplan (isocarboxazid), Nardil (phenelzine), Parnate (tranylcypromine), or selegiline
• Pregnant and breastfeeding individuals
• Individuals with tyrosinemia type I or II
• Patients taking the Parkinson’s disease medication Rytary or Sinemet (carbidopa-levodopa)

RELATED: Hypothyroidism vs. hyperthyroidism

The bottom line

“L-tyrosine can be used in conjunction with a diet and lifestyle plan to enhance weight loss, but supplementing L-tyrosine alone is unlikely to produce clinically significant results,” says Giacinto. She recommends taking L-tyrosine before meals on an empty stomach to suppress appetite. Consult your healthcare provider before adding L-tyrosine or any other dietary supplement to your wellness arsenal.