The Role of Insulin in Metabolism and Sports Performance

What's the first thing that comes to your mind when you hear the word "insulin?" Most likely, you're thinking of diabetes and other related conditions. This hormone does a lot more. It's one of the most important muscle building messengers.

Optimum insulin levels can make it easier to gain mass and strength, keep your metabolism up, and lose excess fat. Learning how to control this hormone is the key to muscle growth and good health. Let's see how insulin works and why it's so important to your metabolism and sports performance!


How Does Insulin Work?

Insulin is a hormone that helps your body use and store glucose. It's produced in the pancreas and secreted by its beta cells. After you eat, your blood sugar levels go up. This causes the pancreas to release insulin, which travels through the bloodstream to your cells. Then your cells convert glucose into energy.

However, not all glucose is used for fuel. A part of it is stored as glycogen in your liver and muscles. About four grams of glucose will circulate in the bloodstream of a person weighing 70 kilograms. Another 400 grams will be stored in the muscles, and 100 grams in the liver. The excess is converted into fat.

Your body's capacity to store liver and muscle glycogen is limited to 1,800 to 2,000 calories. That's enough to fuel up to two hours of intense exercise. Without insulin, glucose cannot be used or stored for energy, so it stays in your bloodstream.

This hormone also keeps your blood glucose levels from getting too high or too low. If you eat a high-carb meal, insulin helps your body store the sugar and releases it when your blood glucose levels drop. As your blood sugar increases, your pancreas produces more insulin.

Every cell and tissue in your body relies on this hormone to take glucose from the blood for fuel. When you have type II diabetes, your body loses its ability to use insulin effectively.

Type I diabetes impairs your body's ability to produce insulin altogether. In this case, the beta cells in your pancreases are either destroyed or damaged. That's why people with this disorder need insulin shots.


Why Is Insulin Important?

By now, you should have a pretty good idea of how insulin works and why it's so important to your health. This hormone plays several roles in your body, including:

·       Helps convert glucose into energy and distribute it to your cells

·       Enables your liver, muscles, and fat cells to store excess glucose

·       Regulates glucose uptake, oxidation, and storage

·       Allows glucose, creatine, and amino acids to enter your muscles

·       Prevents your body from using fat for fuel


Indirectly, this hormone promotes muscle growth and repair. It relaxes and dilates your blood vessels, allowing for more blood to reach your tissues. This leads to better nutrient absorption and increased vascularisation. It allows glucose, creatine, and amino acids to enter your muscles, stimulating hypertrophy.

Insulin also helps prevent catabolism by helping your body store glycogen in the muscles. Furthermore, it contributes to several biochemical reactions that increase protein synthesis. That's why this hormone is critical to building mass.

Pro bodybuilders (or even your local gym-rat) often inject insulin to stimulate protein synthesis, which makes it easier to gain muscle and recover from training. This practice is extremely dangerous, though.

While insulin shots are great for packing on mass, it also promotes fat storage - especially when combined with a high-carb diet. Additionally, the wrong dosage can lead to hypoglycemic shock. Increased sweating, brain fog, hand tremors, arrhythmia, reduced muscle strength and coordination, loss of alertness, double vision, and extreme fatigue are common side effects. A single dose could lead to death.

The key to building muscle and burning fat is to manipulate your insulin levels through diet. Ideally, you should eat your carbs around workout time. (The metabolic window)

What Causes Insulin Resistance?

Some experts blame insulin for the obesity epidemic. Even though insulin promotes fat storage, it doesn't directly cause weight gain or diabetes. Blood sugar fluctuations are the culprit.

Whenever you eat high-carb foods, your blood sugar levels increase. Protein and fats, by comparison, have a negligible impact on blood glucose levels. A high-carb meal will raise your blood sugar and cause glucose to build up in your bloodstream. Heavy meals have a similar effect. In either case, you'll experience blood sugar spikes followed by crashes.

Over time, blood sugar fluctuations affect your body's ability to use insulin. This causes damage to your nerves, organs, and blood vessels. In the long run, it may lead to insulin resistance, which is a major risk factor for diabetes and metabolic syndrome.

Insulin resistance affects one in three Americans and is a big problem here in Australia. Contrary to popular belief, this isn't a disease, but a metabolic state that causes your cells to become less responsive to insulin. As a result, your body begins to produce too much of this hormone to keep blood glucose levels within normal limits.

When secreted in large amounts, insulin can lead to weight gain, hyperglycemia (high blood sugar), prediabetes, heart and kidney disease, type II diabetes, and more. Even though it's hard to tell what causes insulin resistance, certain factors have been linked with this disorder:

·       Being obese or overweight

·       Chronic stress

·       Prolonged use of steroids

·       Lack of exercise

·       Poor nutrition

·       A high-sugar intake over long periods of time

·       Polycystic ovary disease and Cushing’s disease

·       Inflammation

·       Fatty liver disease


Additionally, some people are more likely to develop this condition than others. Individuals over 45 years old, as well as those with a family history of diabetes, have a higher risk of insulin resistance. The same goes for women with a waist circumference larger than 35 inches and men with a waist circumference larger than 40 inches. Studies indicate a strong link between abdominal obesity and this condition.

If you have high triglycerides or hypertension, you're at risk for insulin resistance too. Indigenous Australians, Asian-Americans, Native Americans, and African Americans are genetically predisposed to this disorder. However, there are ways to mitigate your risk. Keeping your blood sugar levels under control is essential.


The Symptoms of Insulin Resistance

Insulin resistance is a silent disease, at least in the first stages. As it progresses, you may experience increased hunger, tiredness, poor mental focus, tingling sensations in your hands or feet, and frequent urination. Most sufferers also report extreme thirst and recurring infections.

The best way to determine whether or not you have insulin resistance is to take the A1C test. This is also used to diagnose diabetes and pre-diabetes. If you're overweight and have a sedentary lifestyle, get tested regularly. Do the same in case you have a parent or sibling with diabetes.

Insulin resistance won't necessarily lead to diabetes or metabolic syndrome. Simple lifestyle changes, such as losing weight, exercising more, and cutting back on carbs, may help prevent these complications and improve insulin response. Low-carb and ketogenic diets and strength training have been shown to prevent and even reverse insulin resistance.


How Insulin and Fat Storage Work

While it's true that insulin promotes fat buildup and inhibits fat breakdown, it doesn't directly cause weight gain. It all comes down to what you eat.

You see, weight loss isn't all about calories in versus calories out. A diet can be high in calories and yet, lead to weight loss as long as it's low in carbs. Let's see a few examples.

In a study conducted on 83 obese subjects, those who went on a ketogenic diet for 24 weeks experienced a significant reduction in total body weight, body mass index, triglycerides, and cholesterol levels. Their blood sugar levels dropped too.

Other studies have found that ketogenic diets can reduce diabetes risk and improve cardiovascular health. Furthermore, they may reverse diabetes symptoms, such as retinopathy and neuropathy.

A typical ketogenic diet limits carb intake to 30-40 grams per day. Some keto diet plans go as long as 10 grams of carbs a day. When your glycogen stores run low, your body can use fat for fuel. Additionally, dietary fat increases satiety, curbs sugar cravings, and decreases the hunger hormone ghrelin levels. At the same time, it prevents insulin and blood glucose spikes, which further contributes to weight loss.

All in all, insulin is not your enemy. As long as you keep it under control, weight gain is unlikely to occur. Furthermore, this hormone can make it easier to build muscle and improve your physical performance.

Mammalian target of rapamycin (mTOR), a protein that plays a vital role in cellular growth, is activated by insulin. This substance regulates the anabolic and catabolic signalling of muscle mass, meaning it promotes hypertrophy and reduces muscle breakdown. It also stimulates protein synthesis, which allows you to build lean mass.

As you see, mTOR and insulin signalling is strongly connected. Maintaining optimum insulin levels turn mTOR on, which makes it easier to pack on mass. In fact, acute mTOR inhibition has been shown to induce insulin resistance and cause glucose intolerance.


How to Prevent or Reverse Insulin Resistance

From tweaking your diet and workout program to getting more sleep, there are a couple of things you can do to prevent or reverse insulin resistance. Strength training, for instance, improves muscle quality and improves insulin response even in people with diabetes. It also enhances your overall physical performance and promotes fat loss.

According to a recent study, lifting weights improves the health markers associated with type II diabetes by increasing the effects of a protein that regulates glucose metabolism. This form of exercise also facilitates glucose uptake into the muscles and reduces abdominal fat, which is a major risk factor for diabetes.

In a clinical trial involving nine older diabetic men, those who engaged in a strength training program for 16 weeks experienced a 10 percent reduction in visceral and subcutaneous fat. Their insulin sensitivity has increased by 46.3 percent, while their fasting blood glucose levels have dropped.

Another way to improve insulin response is to go low-carb. Bread, grains, flour, sugary treats, and other high-carb foods cause your blood sugar to rise. This may lead to insulin resistance in the long run. Research shows that low-carb diets can help prevent blood glucose spikes and increase insulin sensitivity.

For best results, eat your daily carbs before and after training. This way, your body will use them to build muscle, fuel your workouts, and recover from exercise. Avoid or eliminate carbs later in the day when you no longer need them as an energy source.

Also, remember to practice portion control. Heavy meals tend to increase blood sugar levels and cause digestive distress. If you're hungry, eat nutrient-dense foods, such as nuts, seeds, beef, poultry, and eggs. These are high in protein and fats, so they keep you full longer and have little impact on blood sugar levels.

In the case you're overweight, take the steps needed to lose a few kilograms. Obesity, insulin resistance, and diabetes go hand in hand. In a study, obese people who lost 14.5 pounds (6.5kg) over four months experienced a 14 percent decrease in blood sugar levels. Another study has found that weight loss reduced diabetes risk by a staggering 58 percent in healthy individuals.

Other simple ways to improve insulin response is to drink more water, fill up on fibre, and limit stress. Certain spices, such as fenugreek and cinnamon, can help too. Cinnamon, for instance, may reduce blood sugar levels following a high-carb meal. In the long run, it can increase insulin sensitivity and lower your risk of diabetes.

Beware that sleep deprivation and stress can lead to insulin resistance. They both increase the stress hormone cortisol levels, which in turn, stimulates insulin production and affects endocrine function. Plus, you'll have a hard time building muscle and recovering from training if you're skimping on sleep.

Use these strategies to keep your blood sugar within normal limits and optimise insulin response. You’ll not only get better results from your workouts but also lose stubborn fat and have greater energy throughout the day. Your risk of chronic ailments later in life will decrease too.

Look after your body, it’s the only place you’ve got to live.
-Hamish Creighton