If you’ve ever attempted to lean down and reduce body fat, it’s more than likely you’ve come across the infamous hormone insulin and its effect on body fat and muscle growth.
Individuals seeking fat loss often short-change their results by failing to understand the effect of carbohydrates and other dietary factors on the secretion of insulin and body fat storage.
On the other end of the spectrum, those trying to increase their muscle mass and strength need to recognise the importance of insulin for muscle growth and recovery by means of nutrient transportation.
This article explains exactly what insulin is, the functions it performs and how to manipulate insulin through diet, training and supplementation to help you build more muscle and burn more body fat.
What Is Insulin?
Insulin is a hormone that is secreted by the pancreas after certain foods have been ingested. When such foods break down into glucose (sugar) in the body and are sent into the bloodstream, insulin works to shuttle this glucose out of the bloodstream and into cells so it can be utilised as energy.
If the pancreas fails to produce enough insulin, the glucose (sugar) remains in the bloodstream, raising blood sugar levels and potentially resulting in hyperglycaemia. The amount of insulin secreted is dependent on several factors, namely the type and amount of food ingested, and how insulin sensitive (or resistant) an individual is.
Carbohydrates are the main macronutrient which elicits an insulin response, due to their conversion into glucose once digested in the body. Carbohydrate sources vary based on whether they are slow digesting (low glycemic index, complex carbohydrates) or fast digesting (high glycemic index, simple carbohydrates), where the glycemic index (also known as GI) is a measure of how fast a carbohydrate is digested and sent into the bloodstream as glucose.
Simple carbohydrates like processed sugars, dextrose or honey break down far quicker in the gastrointestinal tract and elicit a greater insulin response, as a higher proportion of glucose enters the bloodstream at a single time. Complex carbohydrates like starches, vegetables and grains are comprised of larger molecular chains, taking a greater amount of time to be converted into glucose once ingested. This results in a lesser amount of glucose entering the bloodstream during a given period of time when compared to simple carbohydrates, resulting in less insulin being required to shuttle this glucose out of the bloodstream.
Another important factor dictating how much insulin an individual releases is how sensitive they are to insulin. Greater insulin sensitivity means that the cells in the body can efficiently absorb the glucose, aminos acids or fatty acids being transported by insulin with ease. The more insulin sensitive someone is, the less insulin is required to shuttle nutrients out of the bloodstream and into muscle cells and the liver.
Just as excessive use of caffeine leads to tolerance and a noticeable decrease of its effects, over consumption of simple carbohydrates in isolation has a similar impact on insulin levels. The cells in the body become more and more resistant to uptaking the glucose and nutrients being transported by insulin, which leads to higher blood sugar levels and higher quantities of insulin required to be produced. Over time this excessive simple carbohydrate consumption can lead to insulin resistance; a condition that makes it increasingly difficult to burn body fat and is the precursor to Type II Diabetes.
Where Does Insulin Transport Nutrients?
Insulin is known as one of the most anabolic hormones in the body, promoting the repair and growth of muscle cells. Such cells are lined with receptors, which signal to the muscle to allow insulin and the nutrients it is transporting to enter them.
This assists in protein synthesis (muscle growth) and prevents muscle breakdown (proteolysis), particularly after an intense training session or workout. Many athletes utilise the post workout window as an opportunity to ‘spike’ insulin levels, or encourage the body to secrete a large amount of insulin in order to transport glucose and amino acids into the muscles to spark the recovery process immediately.
Dextrose is a simple carbohydrate that has long been used by bodybuilders and athletes which elicits a major insulin response due to how quickly it converts into glucose and enters the bloodstream (dextrose barely has to be digested – learn more about about it here). Whey protein also elicits a high insulin response, due to how quickly it is absorbed in the body, providing muscle tissue with the necessary amino acids and whole proteins to commence recovery and growth.
Sounds pretty straightforward doesn’t it? Simply consume some rapidly digesting dextrose combined with some fast acting whey protein, and enjoy the benefits of them being stored in muscle cells whilst you sit back and grow.
Unfortunately it isn’t that simple, as muscle cells aren’t the only location that nutrients are transported to in the body.
When glycogen stores within muscle cells and the liver are full, or if an individual suffers from insulin resistance and reduced uptake of glucose into the muscle cells, insulin will begin to shuttle glucose and amino acids into fat cells, as they cannot remain in your bloodstream. The end result is increased fat storage, subsequent weight gain and further insulin resistance.
This is why insulin, although the most anabolic hormone in the human body, is also often referred to as a “fat-storage” hormone, as consuming too many carbohydrates has the potential to increase glucose storage within fat cells, which is completely counter-productive to fat loss. In addition when the body releases insulin, it ceases to use existing body fat as a fuel source due to the influx of more readily available energy consumed from food. Hence why those attempting to reduce their body fat fear insulin and manipulate their diet, namely the timing of their consumption of carbohydrates, to avoid the release of insulin.
While increased insulin production can lead to fat storage in the body, the precursor to this is overeating in the first place. Muscle cells can only hold so much glycogen, so repeatedly eating excessive quantities of carbohydrates leads to greater insulin resistance, encouraging the shuttling of glucose, amino acids and fatty acids into fat cells, consequently increasing fat storage.
How To Manipulate Insulin
There are specific protocols that can assist you in utilising insulin effectively as a means to assist you in burning body fat throughout the day and also building muscle size.
For those wanting to predominantly lose body fat, insulin should be kept low at most times of the day to reduce glucose storage in fat cells and to promote the utilisation of body fat as your body’s main energy source. Therefore, carbohydrate intake should be minimised and derived from complex, slow digesting sources such as oatmeal, quinoa and sweet potato.
The ingestion of these low GI, complex carbohydrates should also be timed around workouts, namely pre-workout and post-workout, to support energy and performance and enhance the recovery process. Approximately 45 – 60 minutes prior to training, aim to consume around 30-40% of your total daily carbohydrate intake from low GI sources combined with some lean protein. Even when weight loss is your goal, consuming high GI or fast digesting carbohydrates and whey protein within 15 – 30 minutes after training helps to quickly replenish muscle glycogen and shuttle amino acids into muscle tissue for growth and recovery.
If your goal is to gain muscle mass or support performance training, the same pre workout and post workout nutrition rules apply to influence insulin; the biggest difference will be that the amount of carbohydrates consumed will generally be much greater. Increased insulin production throughout the day is of less concern to the athlete looking to gain muscle mass as low body fat levels are not the end goal, however it would be recommended to focus on consuming predominantly lower GI carbohydrates to keep blood sugar levels stable, body fat levels in check and reduce the risk of developing insulin resistance. By doing so, weight loss will be much easier when it comes time to make dietary changes in an effort to lose excess body fat.
Enhancing Insulin Sensitivity & Reducing Insulin Resistance
The following principles can assist you in managing your insulin levels to optimize your efforts for both fat loss and muscle growth. The better your insulin sensitivity, the easier your muscles can absorb nutrients and in turn build muscle, whist also assisting your body composition goals.
Include Protein and Fats
These two macronutrients take the longest to break down in the body. Accompany your carbohydrate intake with proteins and fats in a bid to slow how quickly carbohydrates convert to glucose in your body. Avoid eating carbohydrates in isolation as this will elicit the greatest insulin response. Ensure that you include protein in each main meal, particularly in your breakfast meal, to ensure your blood sugar levels are stable at the beginning of your day.
Increase Fibre Intake and Use Vinegar
Dietary fibre derives from indigestible components of plant sourced foods which add roughage and bulk to foods, while promoting a healthy digestive system. It helps keep you full as it slows down how quickly your food digests. This is significant when eating carbohydrates, as the slower they digest, the less insulin is released. Most processed carbohydrates doe not contain fibre, so stick to unprocessed, whole food sources which are abundant in fibre, particularly leafy green vegetables. Alternatively, add psyllium husk into your diet, adding it to foods, yoghurt, smoothies, oatmeal or drinking it with water.
Vinegar can assist you in reducing your insulin sensitivity by slowing down the process of converting carbohydrates to glucose, not unlike medications used to treat those with Type II diabetes. Studies revealed that those who consumed vinegar prior to or accompanying their meal had a far smaller insulin and blood sugar response than those who did not. Simply consume 1-2 teaspoons in water before each meal containing carbohydrates.
Supplement With Omega 3 Fatty Acids
Omega 3 fatty acids, which are lacking in processed food sources, can assist the body in becoming more insulin sensitive through increasing the hormone Adiponectin. Salmon, tuna and fish oil supplements are excellent sources of omega 3 fatty acids, which when consumed, heighten the insulin sensitivity of muscle cells by making them more receptive to insulin, enabling nutrients to be shuttled into these cells with greater ease.
Studies revealed that test subjects who supplemented with fish oil also showed a reduction in the presence of the stress hormone Cortisol, and their inflammation levels; both playing a key role in body fat loss. Improving the ratio of omega 3 to omega 6 fatty acids will also assist in reducing inflammation and encouraging better body composition levels, which can be sourced from a good quality fish oil supplement.
Perform Cardiovascular and Resistance Training
Both strength training and cardiovascular exercise have the ability to make muscle cells more sensitive to glucose, and therefore absorb the nutrients they transport more effectively. During exercise, glucose stores are diminished, and therefore must be replenished which makes the post-workout window a fantastic opportunity to refuel your muscles and mitigate the insulin response required to do so. To increase your insulin sensitivity further, finish off your workouts with some exercises to further deplete your glycogen stores, including high repetition circuits, full body movement supersets or high intensity interval training (HIIT).
Use Nutrient Partitioning Supplements
Finally, supplements can be used at the time you ingest carbohydrates to encourage glucose to be stored in muscle cells. This concepts is known as nutrient partitioning, and has been used by bodybuilders for several decades.
Extracts that have been shown to encourage nutrient partitioning include:
- Cinnamon (Found in ATP Science T432 Plus)
- Banaba Leaf
- Alpha Lipoic Acid
Insulin serves an important purpose in the human body to keep you alive and healthy. Understanding how insulin can be manipulated is paramount to achieving your goals, particularly for individuals seeking fat loss or those wanting to maximise muscle growth and recovery.
Insulin sensitivity can be manipulated through your nutritional intake, exercise regime and supplementation, helping you to achieve your muscle building and body composition goals.
Choose your sources of carbohydrates wisely, opting for complex, low GI foods most of the time, whilst utilising high GI carbohydrates such as dextrose post-workout to purposely elicit an insulin response, promoting recovery, growth and anti-catabolism.
Adhere to these principles and take control of your insulin today!