The role of insulin in weight regulation
Insulin is a hormone that has many roles and functions in our body. In this article I’m going to focus on its effect on weight maintenance. We’ll go over what happens with insulin when we eat. Why we call it a “storage” hormone, and consequently, its role in weight regulation. In fact it’s very simple: high insulin levels promote weight gain and low levels allow weight loss. So if you are trying to lose weight you should work on reducing your inulin levels. Read on if you want to learn about some simple changes you can make to achieve this goal.
Insulin response to macronutrient composition of a meal
The pancreas secretes insulin in response to eating. While any food intake will trigger this secretion, the amount can be very different. The amount also depends on your metabolic health and the foods that you have eaten. To be more specific, the macronutrient composition of your meal might trigger high amounts of insulin to be secreted into the blood.
There are three macronutrients in our food: fat, protein and carbohydrates. Out of the three, fat is the least stimulating for insulin secretion, followed by protein. Carbohydrates, on the other hand, trigger a really significant release of this hormone. Here is an article on how carbohydrates affect our blood sugar regulation.
Insulin functions as a “storage” hormone
One of the most important messages that insulin sends out to the cells is that nutrients are plentiful and that it’s time to store them. Insulin is what we call an anabolic (storage) hormone.
When we eat, we digest and absorb food fairly quickly. You can imagine a flood of nutrients rushing into the blood stream. Our body whats to move these nutrients out of the blood stream as quickly as possible. However, we can’t turn these nutrients into energy quickly enough. We also are not able to store energy in our body. But we are very efficient at storing nutrients in the form of fat. And that’s exactly what we do! We turn carbohydrates, glucose in particular, into fat easily and store it for future use. We can also store some glucose as glycogen, but that storage space is very limited. And there is almost no limit to how much fat we can put away.
From storing to burning
About 2-3 hours after we eat, the food is digested, absorbed and and packed away from the blood stream into our cells. As a result, our blood glucose levels go down and insulin levels decline as well. A low insulin level is a signal to the cells that it’s time to switch from anabolic mode (storage) to catabolic mode (burning). So our cells start breaking down the nutrients that they just stored. Specifically, fat cells start sending fatty acids back into the blood stream to provide nutrients to other parts of the body like our heart or other muscles.
Yes, there are other hormones that participate in this important process of storing and burning of nutrients but insulin is the key. A low insulin level gives “permission” to fat cells to start breaking down triglycerides and sending out free fatty acids that provide the body with energy in between meals. And that’s how energy is kept available for the body to function even if the next meal is not available for a while.
To summarize this fairly straight forward process of storing and burning: we eat, insulin goes up, we store nutrients, insulin goes down, then we break down and burn stored energy. That’s how healthy physiology of weight maintenance works.
When insulin levels are too high
Now let’s take a look at what happens when insulin secretion or signaling is not working optimally. There are many reasons why this could happen. For example, there are certain eating habits and foods that can overstimulate insulin secretion.
First of all, the frequency of eating or snacking. Many people are convinced that they need to eat small portions throughout the day to control appetite and weight. So that’s what they do, grazing throughout the day. The second reason for over secretion of insulin is the high intake of processed carbs. A diet full of crackers and cookies, fruit juices and sweetened drinks, sweet yogurts and sweet cereals – all these foods tend to push our insulin levels trough the roof.
When insulin levels remain high over longer periods, we remain in “storage mode” longer. Due to that the delicate balance of storing and burning is skewed toward storing and we start putting weight on. When insulin levels are high, fat – this wonderful source of energy – is “locked up” inside the fat cells. It’s not made available to the rest of the body and many tissues become semi-starved. As a result, we get hungry. Yes, high insulin levels make us hungry! And when we eat to satisfy that hunger, we end up repeating the cycle, gaining more weight in the process.
Insulin resistance and its vicious cycle
When over-secretion of insulin continues for a long time our tissues become resistant to it. As a result the pancreas has to increase its work and produce more and more insulin to do the job, perpetuating the cycle. Here is an article on insulin resistance and the health consequences that it might lead to. Another excellent resource of information on this topic is the book by Gary Taubes Good Calories Bad Calories.
To break the cycle – to reduce cells’ resistance to insulin, lower insulin levels, and lose weight – we need to limit our carbohydrate intake and eat fewer times a day. Intermittent fasting is a very effective way to do this. You can start by making your overnight fast longer. Gradually move your dinner to an earlier hour and/or your breakfast to a later hour.