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Amino Acids for Weight Loss - Do Supplements Work?

Amino Acids for Weight Loss - Do Supplements Work?

Reading Time: 6 minutes 55 seconds


DATE: 2022-09-07

As a trainer, you've probably heard hype about amino acid supplementation. Most of this comes from the weight room where serious lifters use BCAAs (branched chain amino acid) to improve muscle development post-workout. But now there may be some proof that amino acid supplements, not just protein supplements, could support weight loss.

Always be sure to stay within your scope of practice as a personal trainer. But also make sure you're up to date on the latest trends and science surrounding the world of health and fitness. So, here's what you need to know if your clients ask about taking amino acid supplements.

What Are Amino Acids and Essential Amino Acids?

Amino acids are small molecules that link together to make larger protein molecules. They are often referred to as the building blocks of proteins. There are 20 amino acids the human body needs to grow and function. Eleven of these we can metabolize, but nine must be consumed. These nine are the essential amino acids, or EAAs:

  1. Histidine

  2. Isoleucine

  3. Leucine

  4. Lysine

  5. Methionine

  6. Phenylalanine

  7. Threonine

  8. Tryptophan

  9. Valine

All animal products—meat, poultry, fish, dairy, eggs—contain the essential amino acids. To get all the EAAs in a plant-based diet it is important to eat a variety of foods that contain some number of the nine: whole grains, legumes, vegetables, seeds, and nuts. Soy, quinoa, and buckwheat are the only plants that have all of the EAAs and make a complete protein.

Amino acids play a number of important roles in the body and for good health, not least of which is in the building and maintenance of proteins and muscle tissue. Other reasons we need these molecules in our diets include:

  • Synthesizing hormones

  • Synthesizing neurotransmitters

  • Regulating immune function

  • Producing and regulating energy

  • Building structural proteins for connective tissue in joints and skin

  • Absorbing essential minerals

  • Regulating blood sugar

  • Protecting nerve cells

It isn't difficult for most people to get enough amino acids through their diet. But, many choose to supplement protein or even specific amino acids. You can find supplements for specific single amino acids or for groups of amino acids, such as the EAAs.

Check out this essential guide for your female clients: everything you need to know about women and protein.

How Do Amino Acids Work for Weight Loss?

There are many studies that have investigated the potential for amino acid supplementation to support muscle development and weight loss. How these molecules fuel greater weight loss is complicated, but there are a few possible answers:

Amino Acid Supplements May Boost Performance

One way supplementing with amino acids may help you lose more weight is through a boost in exercise performance. If these supplements can give you more energy, relieve fatigue, and improve recovery times, you can maximize workouts to burn more calories and lose weight.

There is some evidence from research that amino acid supplements do just that. A study of 16 athletes found that supplementing with amino acids improved strength training performance, improved recovery after workouts, and reduced soreness in muscles post-workout. (1)

Increasing the Fat Burn

Multiple studies have shown that there may be a boost in fat burning when you supplement with amino acids. An increase in metabolizing fat will definitely lead to greater weight loss if it truly works. One study showed that daily amino acid supplementation decreased the percentage of body fat in men already heavily involved in strength training. The decrease was significant compared to men who used whey protein or just sports drinks after workouts. (2)

Unfortunately, there have been other studies looking to find out if amino acid supplementation can burn more fat, but with mixed results. There needs to be more work and better studies to find out if it is really the supplement that promotes fat loss or if there are other factors involved.

Help your clients learn how to burn fat, not muscle as they lose weight. Check out this ISSA blog post on the subject.

Using Amino Acids for Weight Loss May Promote Muscle Building

The potential ability of amino acid supplements to increase fat burn may be related to muscle growth. The more muscle mass you have, the greater the potential you have for losing fat and burning calories. Muscle tissue uses more energy than fat tissue, so as you build up muscle, your metabolism revs up and you burn more calories.

So, if amino acid supplementation can help you build more muscle, it can potentially boost weight loss. The key here may be to supplement with BCAAs, or branched-chain amino acids. Of the nine essential amino acids, three have a structure with branched chains: isoleucine, leucine, and valine. Leucine may be the most important of them all in terms of muscle growth.

There is evidence that these three amino acids play a bigger role in muscle building than the others, which is why BCAA supplements have become so popular in the weight room. Studies have shown that these amino acids may improve muscle development by activating certain enzymes after a workout. (3)

Researchers have also shown that BCAAs can help you maintain muscle mass even while restricting your diet. (4) This may mean these supplements are especially helpful in weight loss programs.

Stimulating Growth Hormone

Somatotropin, or STH, is a growth hormone that the body produces mostly at night, during sleep. It stimulates the building of protein from amino acids and the oxidation of fat. One way to burn fat and lose weight is to have more of this growth hormone. But you can't just get a supplement or injection of it. What you may be able to do is supplement with the amino acids that stimulate the secretion of STH.

The essential amino acid methionine, and the non-essential amino acids arginine and glutamine, may be able to do this and promote weight loss. There is some evidence that taking these amino acid supplements on an empty stomach before bed can increase STH secretion and fat loss.

Blocking Fat Storage with Glutamine

There may be another reason to supplement with glutamine for greater weight loss. Glutamine can actually be converted to glucose, the sugar that provides the body's main source of energy, and do so without impacting the hormones that stimulate fat storage.

This means that glutamine can provide energy without pushing the body to store extra energy as fat. It may also reduce sugar cravings for some of the foods that tend to make us fat in the first place, as well as alcohol. Other glutamine benefits may include helping with gut health and immune functions when the body is stressed.

L-glutamine is the most common amino acid in your body. It benefits the immune system and helps with protein synthesis. For this reason, bodybuilders used to use glutamine supplementation to help with building muscle mass and muscle recovery. However, using glutamine supplements for this purpose has since been proven ineffective.  

What About an Amino Acid Injection for Weight Loss?

Some weight loss clinics promote lipotropic injections (along with diet and exercise) as a way to promote fat burning and weight loss. The lipotropes used typically include a mix of amino acids, minerals, and vitamins, such as the following: 

  • Vitamin B12

  • Vitamin B6

  • BCAAs

  • Phentermine

  • Methionine

  • Choline

  • Inositol

While a lipotropic injection is not regulated like a typical prescription drug, it is best to talk with your doctor before trying them. The effectiveness of these weight loss injections has not been proven. Excessive amounts of some ingredients may impact the effectiveness of other drugs and can cause side effects, such as fatigue, constipation, diarrhea, increased heart rate and more. 

Learn more: What You Need To Know About a B12 Injection For Weight Loss 

The Limitations of BCAAs - Supplementing with EAAs

The evidence supporting the role of BCAAs in muscle development is strong, and this is already a popular supplement with weightlifters. But there is also proof that these three amino acids alone are not enough. What you really need to build muscle to support weight loss is all of the nine essential amino acids.

A study from 2017 supplemented participants with BCAA or a placebo after strength training workouts. The researchers concluded that BCAA supplementation does improve muscle growth, but that it has a limit. The better way to maximize gains in muscle tissue after working out, according to this study, is to supplement with all of the essential amino acids, not just BCAAs. (5)

A better choice, if you want to supplement with amino acids, is to find a product that includes all the EAAs, not just the BCAAs. There may be some added benefit to choosing an EAA supplement that includes extra BCAAs, especially leucine.

What Are the Side Effects of Amino Acid Supplementation?

There may not be many significant risks to increasing your amino acid consumption via a BCAA supplement, but there still can be some side effects. Consider these side effects of amino acid supplementation (6):

  • Nausea

  • Abdominal pain

  • Vomiting diarrhea

  • Headache

  • Interference with certain medications

  • Interference with blood glucose levels

The Case for Reducing BCAAs

As if weight loss research and advice weren't already confusing, now there is new evidence showing that a diet that restricts BCAAs may actually improve weight loss. Researchers at the University of Wisconsin found that a diet lower in BCAAs improved symptoms in patients with metabolic syndrome, a condition that includes high blood sugar, high cholesterol, and excessive abdominal fat. The diet with fewer BCAAs helped patients get leaner and regulate blood sugar. (7)

It's important to realize that this study was conducted on lab mice, and results with lab animals don't always translate to humans. Also, the mice in the study were obese, so the use of BCAAs in this way may only apply to people who are obese or have metabolic syndrome.

Talking with Your Client About Amino Acid Supplements

So, should your clients focus on weight loss supplement amino acids? There are no serious risks associated with supplementing amino acids when sticking to the recommended dosage. Of course, there may be individual health reasons a person should not use these supplements, so always tell your clients to check with their doctors before starting any new product.

Check out the ISSA's course for becoming a Nutrition Coach to learn more about diet, nutrition, supplements, and counseling clients on the foods they choose. Join the Nutritionist program today!

  1. Waldron, M., Whelan, K., Jeffries, O., Burt, D., Howe, L., and Patterson, S.D. (2017). The Effects of Acute Branched-Chain Amino Acid Supplementation on Recovery from a Single Bout of Hypertrophy Exercise in Resistance-Trained Athletes. Appl. Physiol. Nutr. Metab.42(6), 630-6. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/28177706

  2. Stoppani, J., Scheett, T., Pena, J., Rudolph, C., and Charlesbois, D. (2009). Consuming a Supplement Containing Branched-Chain Amino Acids During a Resistance-Training Program Increases Lean Mass, Muscle Strength, and Fat Loss. J. Int. Soc. Sports Nutr.6(Suppl 1). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3313152/

  3. Blomstrand, E., Eliasson, J., Karlsson, H.K.R., and Kohnke, R. (2006). Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise. The Journal of Nutrition. 136(1), 269S-73S. Retrieved from https://academic.oup.com/jn/article/136/1/269S/4664134

  4. Dudgeon, W.D., Kelley, E.P., and Scheett, T.P. (2016). In a Single-Bind, Matched Group Design: Branched-Chain Amino Acid Supplementation and Training Maintains Lean Body Mass During a Caloric Restricted Diet. J. Int. Soc. Sports Nutr.13(1). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/26733764

  5. Jackman, S.R., Witard, O.C., Philp, A., Wallis, G.A., Baar, K., and Tipton, K.D. (2017). Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis Following Resistance Exercise in Humans. Front. Physiol. Retrieved from https://www.frontiersin.org/articles/10.3389/fphys.2017.00390/full

  6. Holeček M. (2022). Side effects of amino acid supplements. Physiological research71(1), 29–45. https://doi.org/10.33549/physiolres.934790

  7. University of Wisconsin-Madison, School of Medicine and Public Health. (2017, December 21). Study: Diet Limiting Specific Amino Acids May Be Key to Weight Loss. Retrieved from https://www.med.wisc.edu/news-and-events/2017/december/amino-acids-weight-loss/

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