Amino acids are the building blocks of proteins, essential for numerous bodily functions, including muscle building, hormone synthesis, and energy regulation. The potential role of amino acid supplementation in weight loss has garnered considerable attention, particularly within the fitness community.
Understanding Amino Acids
Amino acids are organic compounds that combine to form proteins. There are 20 amino acids, classified as essential and non-essential. The body can synthesize non-essential amino acids, while essential amino acids (EAAs) must be obtained through diet. Animal products like meat, poultry, fish, dairy, and eggs are complete protein sources containing all EAAs. Plant-based diets require a variety of foods like whole grains, legumes, vegetables, seeds, and nuts to ensure adequate EAA intake. Soy, quinoa, and buckwheat are exceptions, as they are complete plant-based proteins.
Roles of Amino Acids
Amino acids are vital for:
- Synthesizing hormones and neurotransmitters
- Regulating immune function
- Producing and regulating energy
- Building structural proteins for connective tissue
- Absorbing essential minerals
- Regulating blood sugar
- Protecting nerve cells
How Amino Acids May Support Weight Loss
While consuming fewer calories is widely accepted for weight loss, recent research highlights specific amino acids, such as cysteine, as potentially playing a key role.
Cysteine and the Browning of Fat
A study published in Nature Metabolism suggests that cysteine, a sulfur-containing amino acid, can trigger the conversion of white fat cells into brown fat cells. Brown fat cells are more metabolically active, burning energy to produce heat and maintain body temperature. Pennington Biomedical researchers Dr. Eric Ravussin and Dr. Krisztian Stadler contributed to this study. "In addition to the dramatic weight loss and increase in fat burning resulting from the removal of cysteine, the amino acid is also central to redox balance and redox pathways in biology," said Dr. Stadler. This discovery, based on human trials and animal models, opens new therapeutic avenues for treating obesity.
Read also: Explore solutions for essential amino acid deficiency
In the human trials, researchers examined fat tissue samples from participants in the CALERIE clinical trial, who reduced their calorie intake by an average of 14% over two years. The tissue samples came from participants in the CALERIE clinical trial, which recruited healthy young and middle-aged men and women who were instructed to reduce their calorie intake by an average of 14% over two years. Analysis of these samples revealed changes in metabolites, compounds formed when the body breaks down food and stores energy. The study showed that those who reduced their calorie intake had lower levels of cysteine and a reprogrammed metabolic system. "Reverse translation of a human caloric restriction trial identified a new player in energy metabolism," said Dr. Ravussin. In the animal models, researchers provided meals with reduced calories.
Boosting Exercise Performance
Amino acid supplementation may improve exercise performance by providing more energy, reducing fatigue, and enhancing recovery times. This can lead to more effective workouts and increased calorie expenditure. It 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.
Increasing Fat Burning
Some studies indicate that amino acid supplementation may promote fat burning, potentially leading to greater weight loss. 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.
Promoting Muscle Building
Amino acids, particularly branched-chain amino acids (BCAAs), are crucial for muscle growth and maintenance. Increased muscle mass can elevate metabolism, leading to more calories burned at rest. 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.
Stimulating Growth Hormone
Certain amino acids, such as methionine, arginine, and glutamine, may stimulate the secretion of somatotropin (STH), a growth hormone that promotes protein synthesis and fat oxidation.
Read also: Amino Acids and Weight Loss
Blocking Fat Storage with Glutamine
Glutamine can be converted to glucose without stimulating fat storage hormones, potentially reducing sugar cravings and supporting gut health and immune function.
The Role of Essential Amino Acids (EAAs) and Branched-Chain Amino Acids (BCAAs)
Essential amino acids (EAAs) and branched-chain amino acids (BCAAs) play significant roles in supporting the preservation of lean body mass (LBM) during weight loss induced by lifestyle interventions, pharmacotherapy, or bariatric surgery.
Benefits of EAAs and BCAAs
Evidence suggests that EAA and peptide-based supplementation may help preserve LBM during periods of reduced energy intake, particularly when protein intake from whole foods is limited. Benefits appear more consistent when supplementation is combined with resistance exercise. BCAA supplementation alone has shown variable effects, especially in sedentary individuals or when total protein intake is already sufficient. Anabolic resistance associated with obesity may attenuate the muscle protein synthesis response to dietary amino acids.
EAAs are crucial because they cannot be synthesized by the body and must be obtained through diet. They are essential for muscle protein synthesis (MPS) and overall metabolic health. BCAAs, a subset of EAAs including leucine, isoleucine, and valine, are particularly important for muscle development and energy production during exercise.
How BCAAs Work
BCAAs are metabolized in extra-hepatic organs like skeletal muscle, adipose tissue, the heart, the kidney, and the pancreas. Within these tissues, BCAAs may be directed toward protein synthesis, mitochondrial oxidation, or storage within the intracellular amino acid pool. In the central nervous system, BCAAs serve as nitrogen donors for the synthesis of neurotransmitters such as GABA and glutamate, and they may also act as precursors in sterol and glucose biosynthetic pathways.
Read also: Essential Amino Acids Guide
BCAA oxidation is initiated by a reversible transamination step catalyzed by BCAT1/2, which converts BCAAs into their corresponding BCKAs. These intermediates are then irreversibly decarboxylated by the mitochondrial BCKDH complex, yielding acyl-CoA derivatives. The resulting acyl-CoAs are further metabolized to form acetyl-CoA and succinyl-CoA, which feed into the TCA cycle.
Limitations of BCAAs: The Case for EAAs
While BCAAs are popular for muscle development, research suggests that supplementing with all nine EAAs is more effective for maximizing muscle growth after exercise. 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.
Potential Risks and Side Effects
While amino acid supplementation is generally considered safe, potential side effects include:
- Nausea
- Abdominal pain
- Vomiting
- Diarrhea
- Headache
- Interference with certain medications
- Interference with blood glucose levels
Methionine Toxicity
Methionine is the only EAA that can be considered toxic. Methionine toxicity is dependent on the intermediate metabolite formed when cysteine and/or cystine have to be synthesized from methionine to match metabolic requirements. This metabolic intermediate, homocysteine (Hcys), may have different toxic effects. A most interesting one is that Hcys seems to control increased expression of β-hydroxy-β-methylglutaryl coenzyme A (HMG-CoA) reductase in arteries walls.
The Arginine Paradox
Arginine is one of the non-essential AAs that can become âconditionally essentialâ, i.e., not synthesized in adequate amounts during highly demanding pathological conditions. It is the indispensable substrate for NO production, but chronic arginine supplementation proved to increase mortality in patients after myocardial infarction; thus, we must answer in the affirmative, but its supplementation is still recommended in different pathological conditions.
The Case for Reducing BCAAs
New evidence suggests that a diet restricting BCAAs may improve weight loss and metabolic health. 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.
Safety and Dosage Considerations
Few data are available on amino acid toxicity, and only one essential amino acid may be considered to have clinically relevant toxicity: methionine, because it is transformed into a toxic intermediate, homocysteine, when cysteine synthesis is required by metabolic needs. Matching of stoichiometric ratios between methionine and cysteine may solve the problem of supplying sufficient amounts of sulfur to the body.
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.
Lipotropic Injections
Some weight loss clinics promote lipotropic injections, containing a mix of amino acids, minerals, and vitamins, to promote fat burning and weight loss. While not regulated like prescription drugs, it is best to talk with your doctor before trying them due to potential side effects and interactions.
Nutritional Considerations and Amino Acid Ratios
Nitrogen supply is pivotal for the maintenance of life. Amino acids can be utilized to synthesize both glucose and lipids. The opposite, i.e., production of amino acids from either one of them, is not possible in the absence of other amino acids as donors of nitrogen. The quality of amino acid content in protein has been re-evaluated recently, and the relevance of essential amino acids has been repeatedly underlined. Essential amino acid requirements in different mammals are not identical, and ratios among them should be taken into account when projecting an efficient formulation.
Recent research has demonstrated that genes respond to different qualities and quantities of nutritional supply, and increased provision of essential amino acids increases lifespan in animal experiments through mitochondriogenesis and maintenance of elevated rates of synthesis of anti-oxidant molecules. Moreover, genetic expression of key controllers of synthesis, like mTOR, may be particularly important for understanding skeletal muscle maintenance.
Calculation of nitrogen balance provides the gold standard for the evaluation of matching nitrogen demand and supply.
Clinical Evaluation of Protein Malnutrition
In my opinion, dynamical evaluation of changes in synthesis by repeated monitoring of plasma concentrations of visceral proteins (albumin, transferrin, prealbumin, or rethinol-binding protein) would be the best clinical parameter for general practitioners to evaluate their patients. A prerequisite is that the liver has a sufficiently large working cell mass. All patients with albumin plasma levels below normal should be considered at risk of protein malnutrition independent of any other medical condition. Such finding should prompt further clinical investigation. Albumin has a long half-life (about 3 weeks), but other proteins like transferrin (half-life about 1 week) or prealbumin (better identified as trans-thyretin, or TTRâhalf-life of about 48 h) or rethinol-binding protein (RBPâhalf-life of about 12 h) can be used to monitor more accurately and at shorter intervals success or failure of treatment options. In any case, any patient with plasma albumin levels of 3.2 g/L should be considered severely malnourished and possibly cachectic and treated aggressively. Indeed, low plasma albumin levels are predictors of poor prognosis in different pathological conditions.