Carbohydrate and insulin: get to know your hunger hormones
Carbohydrate, protein and fat are macronutrients that all act very differently in the body and all food contains one of these or a mix. Each macronutrient triggers a different responses from your metabolic hormones such as insulin and leptin and this ultimately helps your body obtain energy from calories. All macronutrients have a place in a healthy diet and ideally should come from whole foods.
To understand the importance of eating plenty of fat and protein in addition to your healthy carbohydrates, these two articles look at the different hormones that are at play when you eat.
1. Insulin and glucagon: hormones for carbohydrate storage
Carbohydrate in the body
Everything that is not protein or fat is carbohydrate. That means sugar and cakes. But it also means carrots and broccoli. And yes it certainly means grains.
When you eat carbohydrates they are broken down into simple sugars (monosaccharides) such as glucose. (Fructose is another single chain carbohydrate, that works differently in the body to glucose). In this post we are going to look at glucose.
When you eat glucose-based carbohydrates, like starchy vegetables, bread, grains and cakes they become glucose molecules that are a usable form of energy for your brain and body. Glucose from any source behaves the same once it is broken down, although you’re going to get more out of your calories if you’ve eaten something that is nutrient dense (ie: broccoli as opposed to bread).
Like all nutrients your body absorbs glucose through the walls of your intestine. The glucose enters your blood stream causing a spike in your blood sugar. First and foremost the liver makes sure that your brain and red blood cells take what they need, which causes the sudden surge of energy you feel after you eat something sweet.
It is then time for the storage hormone, insulin, to get to work and deliver the energy to your cells.
Insulin: your carb storage hormone
- Insulin is produced by the pancreas, mainly in response to glucose. It is the hormone that allows your body to store energy as well as important micronutrients. Everything you eat will produce some degree of insulin response. Depending on how much a food raises your blood sugar this response might be very low, but it will always be there. Insulin is also supposed to act as a ‘fullness’ hormone by assisting your cells to gain energy, which tells your body that you’ve been fed.
- Insulin allows your brain and cells to take the glucose they need for energy. Next some will be stored in the muscles and liver as glycogen. The amount of glycogen you can store depends on how active you’ve been. When you exercise (provided you’ve not just eaten and have glucose circulating in your system) then your body will taken energy in the form of glycogen from your muscles.
- When your muscles and liver cannot store any more glucose as glycogen and there is excess glucose, your body must get it out of your blood stream. High blood sugar is toxic so insulin will help you store the remaining glucose as fat. The body has unlimited capacity for this kind of storage. Triglycerides are fats that circulate in the blood and adipose tissue is body fat. For obvious reasons we want to limit the amount of both of these.
- Over a period of a couple of hours insulin will bring your blood sugar back to normal, preventing it from remaining high. If our bodies did not produce insulin then we could not get the energy that we need from our cells. This is the problem that diabetics face.
Insulin and diabetes
The inability of insulin to transport glucose into your cells will lead to your body thinking it’s starving because the cells cannot get the energy they need. It will also lead to dangerously high blood sugar. Type 1 diabetes is an autoimmune condition where the body attacks the insulin producing cells in the pancreas. When a Type 1 diabetic eats something that raises their blood sugar, their body cannot use insulin to store the energy and their blood sugar will remain high, which is dangerous. It is therefore essential that diabetics inject themselves with insulin to normalise their metabolic process.
It’s not just diabetics that need to worry about insulin. When we constantly eat carbohydrate, every few hours “to keep our metabolism burning” as we are advised to do, then our insulin production has to work over time. If you remember that any kind of carbohydrate will raise your blood sugar, you should see why insulin resistance is becoming a big problem in the western world where diets are rich in grains.
Insulin resistance occurs when your body has to constantly produce insulin to deal with the constant doses of carbohydrates that you’re putting in. And this isn’t just the result of sugary sweets. If you have cereal or toast for breakfast, a pastry and fruit for morning tea, a sandwich or pasta for lunch, sugary ‘low-fat’ (high sugar) yoghurt for afternoon tea (I don’t need to go on), then you are continually loading your body with glucose and it must constantly produce insulin to process it.
If you do this all day everyday without appropriate protein and fats to balance things out then eventually your body loses its ability to sense the insulin secreted by your pancreas. Basically your body has become so used to constant doses of insulin, that it just starts to ignore it.
This is the beginning of insulin resistance, which can lead to Type 2 diabetes. Type 2 diabetes is when your body:
- Cannot sense that insulin has been produced; or
- Cannot produce enough insulin to deal with glucose.
This is why type 2 diabetes is a metabolic disorder as opposed to an autoimmune condition. It is common in people that are overweight because chronically high blood sugar can lead to weight gain and insulin resistance.
According to the International Diabetes Federation (IDF), more than 371 million people across the globe have diabetes and this figure is predicted to rise to over 550 million by 2030.
To avoid chronically elevated blood sugar and the associated conditions it is wise to lower your carbohydrate consumption (particularly from nutrient poor foods like grains) and instead eat a variety of foods that are good sources of protein and healthy fats.
Glucagon (not to be confused with glycogen) is the hormone that causes your body to release nutrients from your various stores to give you energy. Glucagon and insulin do the opposite jobs, so when one is working the other is not. Both hormones are produced by the pancreas. While insulin works to lower your blood sugar, glucagon brings it back up again to ensure you have enough energy.
If you are constantly feeding yourself carbohydrate, prompting the ongoing production of insulin, then glucagon won’t get a turn. It is preferable for your body to be in a state of glucagon dominance because this means you will burn your stored nutrients (including fat) as fuel. This will stop you feeling hungry, as soon as your blood sugar drops. This is also why if absolutely necessary your body can last for a few days without food.
Eating dense sources of protein helps to promote a glucagon response, because they do not cause the production of much insulin, particularly in contrast to carbohydrate. Exercise also helps to produce glucagon, particularly if you don’t eat just before hand. When you start moving your body will signal that it needs more energy, so glucagon will get to work to make sure you have enough.
Hyperglycemia and hypoglycaemia: rises and dips in your blood sugar
Hyperglycemia is high blood sugar, before insulin stores glucose away. Hypoglycemia is low blood sugar. When you eat a diet that is high in carbohydrate and without enough protein and fat to stimulate other hormones, then your body gets used to producing a lot of insulin. After a couple of hours when it has stored all the glucose, then you will have a dip in your blood sugar and begin to feel tired and shaky. Only something sweet will fix this.
This is why we feel the need to eat so regularly when our diets are carbohydrate dense and low in fat. Insulin is dominant and constantly putting glucose into storage, so our body is always looking for new energy to replace the lost glucose. As soon as the glucose from your meal is stored and your blood sugar drops, your body will start looking for more energy. If you’re not used to letting the glucagon hormone draw stored energy from muscles and fat, then it will tell you to find more glucose, which manifests as sugar cravings. As shown above, this results in a bit of a blood sugar roller coaster!
If we eat more fat and protein then other hormones come into play and we get a bit better at regulating our blood sugar between meals. In reality, you don’t actually have to eat six times a day to ‘keep your metabolism’ going.