BCAA: A role in preventing muscle loss when dieting?

What are BCAA's

Branch Chain Amino Acids (BCAA’s) are classified as essential amino acids, meaning that we must get them from our diet and are made up of three amino acids, leucine, isoleucine and valine. BCAA’s have had quite a lot of interest from a muscle building perspective as leucine, in particular, is a key trigger of protein synthesis in the body. Protein synthesis is the creation of new proteins… in our muscle cells, this equates to muscle growth... well it does assume that muscle protein synthesis (MPS) outweighs rates of muscle protein breakdown (MPB).

What happens during a fat loss diet?

During a fat loss diet there is the potential that without adequate calories or protein, we are at risk of muscle loss, especially when combined with a training regime. Pretty much all kinds of training stimulate muscle protein breakdown to a certain extent, as it is an essential part of the remodelling process that is required to develop new muscle tissue, or when dieting to help retain the existing muscle tissue. Muscle is put at increased risk when dieting for a long period or with excessive drops in calorie intake. This is because the body enters a state of stress and needs to reduce metabolic output, as the fuel coming into the body struggles to provide enough energy to maintain function that was supported by the previous calorie intake.

It can do this in a few ways, firstly by downregulating hormones such as thyroid hormones and secondly by reducing the amount of metabolically active tissue… in this case muscle. Unfortunately, the body doesn’t know that our intentions might just be to lose a few pounds to look good on the beach and from an evolutionary perspective, these strategies serve as pretty good adaptations to keep us alive until more abundant food sources can be provided.

This is why even in overweight people with lots of energy reserves, they still suffer from these forms of metabolic adaptations as the body doesn’t inherently ‘see itself’ as overweight or unhealthy, it just responds to a reduction in energy that could potentially indicate a prolonged lack of food provision that requires a reduction in energy expenditure for a person to survive.

So where do BCAA’s come into this whole equation?

Well in a few different ways. Firstly, apart from stimulating MPS, several studies have shown they also help reduce MPB. Secondly, some BCAA’s can be converted to glucose through a process of gluconeogenesis, which converts non-glucose substances to glucose. This can provide a potentially muscle protective fuel when energy levels are low. This includes the use of other glucogenic amino acids such as glutamine which is also found in some BCAA supplements. Glutamine is the main amino acid stored in the body, and supplementation has nitrogen (protein) sparing effects that may help to protect muscle tissue.

For many people who train first thing in the morning before a normal (hopefully protein containing) breakfast or for those who like to employ fasted cardio, then the use of BCAA’s and/or glutamine can help provide a protective buffer against muscle loss. This is especially important because our body doesn’t readily store large amounts of protein, unlike carbohydrates and fats, therefore when we wake our body will be pulling much of the amino acids from its main store… the muscles.

Although technically not ‘fasted’ once BCAA’s have been consumed, the benefits of using BCAA’s for those training early in the morning before a full meal containing protein or when using intermittent fasting style diets, is something to seriously consider to keep a positive net protein balance and protect your hard earned gains, especially when on calorie restriction.

In summary

BCAA’s may be of benefit to those on a fat loss diet, especially to those who train in a non-fed condition, or in those who may struggle to eat in a reasonable timeframe before training due to its muscle protecting effects. This might be especially important for those on low carb diets as insulin levels may be low. The increase in insulin (no it’s not the devil!) caused by amino acids is a great way to offer muscle protective effects as insulin reduces MPB pretty much to a standstill, as well as influencing pathways that stimulate MPS.