A common pitfall to fat loss is the decrease in muscle that occurs when you are in an energy deficit. It’s well known that in order to lose body fat, you need to take in fewer calories than you burn. Unfortunately, you don’t just burn body fat when in a calorie deficit. Instead, the body relies to a significant degree on lean tissue, breaking down muscle.
When this happens, metabolic rate decreases as well. Muscle and related lean tissues are the most metabolically costly—much more so than fat tissue—so the number of calories your body burns daily decreases. This reduction in energy expenditure is cited as one reason rebound fat gain is so common.
Therefore, maintaining lean mass during dieting is a top priority. One strategy to achieve this is to increase the availability of amino acids that the body uses to maintain lean tissue. This can be done by increasing protein intake and strategically using supplements that supply the most important amino acids involved in muscle building—the BCAAs. For example, on lower protein diets that provide 15 percent or less of the calories from protein, 70 percent of the weight loss is typically from body fat and 30 percent is from muscle. By simply doubling the amount of protein to about 30 percent of calories, nearly all of the weight loss is from fat even in lean, active individuals.
This article will review the role of protein for fat loss and highlight how BCAAs can be useful for improving body composition.
How Does the Body Build Muscle?
Protein synthesis is the mechanism by which the body builds muscle or restores damaged tissue. Two factors can stimulate protein synthesis:
- Mechanical loading such as weight lifting, and
- Consuming protein-rich foods that provide amino acids, in particular the amino acid leucine.
This is why strength training and eating a higher protein diet are the two best strategies we have for fat loss since together they will preserve lean muscle mass and help to maintain metabolic rate.
Of course, protein foods have additional benefits for fat loss:
- They are very satisfying, and they naturally reduce the number of calories people eat every day. One study found that by increasing protein intake from 15 to 30 percent of the diet, participants ate 441 fewer calories. By the end of the 12-week study they had lost 3.7 kg of body fat.
- Protein is the costliest food for the body to breakdown. The body burns 25 percent of the calories provided in a meal of pure protein during digestion. This means that high-protein diets can boost metabolism by up to 100 calories per day.
- Protein foods improve blood sugar levels, leading to a more moderate, sustained increase in blood sugar compared to high-carb foods that trigger peaks and valleys.
An example of the benefit of protein combined with serious training is a 2013 study that had normal-weight, trained individuals eat 1.6 g/kg of protein on a calorie restricted diet. Compared to a group that ate the RDA of protein (0.8 g/kg), the high-protein intake preserved lean mass and allowed for a 1.9 kg decrease in body fat. By contrast, for the subjects who ate only 0.8 g/kg of protein, 58 percent of the weight lost was from lean muscle mass in the course of losing 1.6 kg of body fat.
A second study found that overweight women who exercised in addition to eating a high-protein diet lost 9.8 kg, of which 96 percent was body fat and only 4 percent was lean tissue. A group that ate a normal-protein (0.8 g/kg), low-calorie diet lost a whopping 2.7 kg of muscle mass.
Can BCAAs Improve Fat Loss?
The BCAAs are made up of three essential amino acids, leucine, isoleucine, and valine. They are essential because they body is unable to synthesize them out of other amino acids, meaning they must be ingested through food or supplements. The acronym BCAA stands for branched chain amino acids—a reference to the branched side chain in their chemical structure that simplifies the job of converting each amino acid into energy.
The BCAAs make up about 35 percent of all muscle tissue and they are a potent stimulator of protein synthesis, increasing activity of the mTOR signaling pathway that is essential for muscle building. One BCAA, leucine, can increase protein synthesis by as much as 145 percent when taken after a strength training workout.
In addition to being useful for stimulating protein synthesis, there is evidence that getting sufficient BCAAs in the diet is associated with leanness. Surveys show that people with higher BCAA intake in their diets have less body fat, more muscle, and better body composition.
For example, a large study of 4,429 subjects found that those with higher BCAA intake were the slimmest and had significantly less chance of being overweight compared to those with lower BCAA intake. In another study, scientists identified metabolic markers that were associated with body fat percentage and found that the higher the serum level of BCAAs, the less body fat subjects had. The association was consistent for both men and women and was independent of exercise participation.
BCAAs can only be gotten in the diet from high protein foods and other surveys show that subjects with higher protein intake have less body fat and more muscle mass regardless of age. In fact, scientists have identified a threshold protein dose of 10 grams of essential amino acids that is associated with leanness.
Naturally, you want to get the majority of your BCAAs and protein from high-protein foods. Chicken, beef, salmon, and eggs top are at the top of the list for providing BCAAs and all animal products are rich in protein and BCAAs: poultry, other forms of red meat, seafood, and dairy.
BCAA and protein supplementation can help round out protein in certain situations such as when you aren’t able to hit your daily protein goal either due to limited of appetite or lack of access to high-quality protein. People who are performing intermittent fasting, individuals suffering injury or chronic disease, vegetarians, and older adults are all populations that can benefit from supplementation.
Additionally, BCAAs may have unique metabolic benefits that encourage improvements in body composition. In a review of the role that the essential amino acids play in body composition, scientists write that the BCAAs “appear to have unique obesity-reducing effects” because they decrease food intake and body weight by increasing the gene signaling of muscle building pathways.
It’s also possible that the BCAAs can improve energy expenditure and fat oxidation. Greater fat metabolism allows for a more flexible metabolism, which can enable fat loss from a combination of training and diet. Getting the body to burn body fat is particularly important for overweight, sedentary individuals who have a dysfunctional metabolism and inability to switch from oxidizing glucose to fat burning. Poor metabolic flexibility indicates a derangement in muscle metabolism that favors the development of obesity and metabolic disease.
Can BCAAs Improve Training Performance When Dieting?
One drawback to dieting is an increase in perceived exertion so that exercise “feels” harder. This is especially true on lower carb diets that deplete glycogen, the muscle’s energy source. Taking BCAAs may help preserve training quality and mood in this situation.
In one study, researchers analyzed what happens when trained athletes performed a high-intensity cycle workout to exhaustion with low muscle glycogen. One group took a protein supplement that provided the BCAAs and the other took a placebo before and during the workout. To review, your body stores the carbohydrates you eat as muscle glycogen, and it favorably calls on glycogen over fat for energy during training. However, an excellent way to lose fat and increase your work capacity is to use training cycles in which you exercise with low muscle glycogen.
The concern is that athletes who train with low glycogen will lose muscle mass over time, which is where BCAAs and protein come in. The study in question found that by taking a BCAA-rich supplement before the exhaustive exercise test, protein synthesis pathways were enhanced post-workout compared to the placebo trial. Researchers suggest that increasing protein availability when glycogen is low is a beneficial way to help athletes to improve body composition without experiencing a decrease in performances. Although not shown in this study, it may also lower the rating of perceived exertion by alleviating central fatigue.
This was seen in a previous study that showed that BCAAs improved mood scores in young men after a tough workout. The BCAA group also recovered faster than a placebo group, reporting less fatigue two hours after the workout. Any coach knows that minimizing the sensations of physical stress and pain during high-intensity training is a benefit for getting trainees to work harder and faster.
How To Use BCAAs To Improve Body Composition?
Pick A Protein Goal
The first step for improving body composition is to identify a daily protein intake goal. Although higher intakes may be ideal in certain situations, a general rule is to get a minimum of 1.6 g/kg of protein daily from high-quality animal-derived sources. Vegetarians may need to bump protein intake up from this number to get the best results.
Spread Protein Intake Over The Course of The Day
Spread your protein intake out over the course of the day, getting a minimum of 20 grams per meal (and ideally at least 30 g per meal). This will help stimulate protein synthesis over a 24-hour period and may pay off in terms of less hunger and higher metabolic rate. Note that most people backload protein, getting more than 50 percent at dinner, while having a low-protein breakfast. Adjusting this profile to frontload protein so that you get 50 percent by noon may assist with fat loss according to some studies.
Favor Animal-Derived Proteins
High-quality protein sources include the BCAA-rich ones listed above (chicken, beef, salmon, eggs) as well as turkey and other forms of poultry, most seafood, all other meat, whey protein, and many dairy products. In contrast, plant-based protein sources are less efficient than animal-derived protein because they lack certain essential amino acids.
Vegetarians will be hard pressed to get optimal levels of the BCAA leucine, which is a powerful stimulator of protein synthesis. Seeds, soy, and some vegetables like watercress do contain leucine but the concentration pales in comparison to whey protein or eggs. Simply put, vegetarians need to bump up their total daily protein intake, and if maintaining lean mass is a goal, find a supplemental source of leucine. Vegetarian-sourced BCAAs are available to meet this need.
BCAA supplements appear to be most effective around workouts and when any of the above three recommendations cannot be met. During training, BCAAs will supply the muscle and lean tissue with the building blocks it needs to maximize protein synthesis. This can pay off in more than just performance benefits: Studies show BCAA can reduce the painful muscle soreness that comes after heavy muscle damaging training. Both trained and untrained volunteers have reported less soreness and one study found a 33 percent lower decrease in maximal strength that coincides with muscle thrashing eccentric exercise.
As mentioned above BCAAs may also help spare glycogen and reduce the “pain” of training, which can pay off in improved endurance. Interestingly, studies show BCAAs can be burned as energy to maintain ATP levels during glycogen depleting exercise by helping the body tap into fat stores. Additionally, BCAAs reduce fatigue of the nervous system by inhibiting uptake of tryptophan into the brain. Tryptophan is used to make serotonin in the brain, increasing tiredness and fatigue. Scientists who study the limits of human performance believe that the real limiting factor in performance is when the brain tells you “I’m done.”
For example, participants who took 300 mg a day of BCAAs for 3 days and then completed an exhaustive exercise trial had 17.2 percent greater resistance to fatigue compared to a placebo, due at least partly to greater fat oxidation in the BCAA trial.
Final Words: BCAAs are a valuable tool to help you get all the amino acids you need, while having exercise performance and recovery benefits that may help you get more out of training. Use them when you need them to optimize body composition and eliminate excess body fat that is holding you back.