Insulin, Chapter 1
This site has an insulin and blood sugar simulator. It illustrates the relationship between eating, rising blood sugar, rising insulin - and of course the subsequent fall of both. But why is insulin involved at all?
Simply put: Pancreatic hormone that signals cells to absorb glucose from the blood. Central regulatory hormone of energy metabolism. is a hormone with many roles. This article covers one of them - specifically the one that tends to work against the goals of a great many people: at the end of the chain sits insulin’s influence on body weight.
Blood Sugar Regulation and Fat Storage
Most people have heard of Chemical name for the sugar commonly measured as blood-sugar. This is what starch is built from, and 50% of table sugar or 45% of HFC. Also known as dextrose. → more - it’s easy to measure, at a doctor’s office, a pharmacy, or even at home. A normal blood sugar level is under 100mg/dL. Put differently: 1g per litre of blood. Across 4–6 litres of blood, that’s about one teaspoon of glucose dissolved in your bloodstream.
After eating, blood sugar typically rises - more or less steeply, and for more or less time, depending on what you eat. Carbohydrates cause the steepest rise, because they’re broken down into glucose in the digestive tract - the very substance measured as blood sugar, of which only 4g needs to circulate at any one time.
A meal containing 50g of carbohydrates means 50g of glucose needs to pass through a bloodstream that normally holds only 4–6g in solution.
Too much blood sugar (even just twice the normal amount, if chronically elevated) is toxic to the body, so it needs to be cleared from the blood as quickly as possible. That’s what insulin is for.
The body releases insulin, which causes receptors in cells throughout the body to respond and remove sugar from the blood. This includes the liver and muscle cells. Both can store limited amounts of sugar (in a slightly different chemical form, as glycogen), so the liver converts any excess sugar into fat. That fat is transported and stored - also with insulin’s help. We know this as weight gain.
The Effect on Energy Balance
Insulin drives the conversion and storage of energy. But it creates a one-way street: as long as insulin levels are elevated, it’s impossible for the body to access stored fat reserves. You can follow this in the simulator: turn on the “fat-burning zone” and “elevated insulin” layers in the chart - the closer insulin is to the fat-burning zone, the more the body can draw on its reserves. The further away, the more it stores.
This simulation shows blood sugar (red) and insulin (blue) with a healthy metabolism, eating 4 meals of 500kcal each. Notice: the higher blood sugar rises, the higher insulin rises too. And both rise and fall by different amounts. Even hours after a meal, insulin levels can still be above baseline.
Rules of thumb:
- The more insulin circulates, and the longer it stays high, the more fat is stored - and for longer.
- The closer insulin stays to the fat-burning zone (ideally right inside it), and the longer that lasts, the more of the stored reserves the body can actually burn off.
Doesn’t look that bad? Let’s compare it with the same daily schedule for someone who has been diagnosed as pre-diabetic, meaning they are gradually becoming insulin-resistant. This is usually recognised by elevated fasting blood sugar, though it could have been detected much earlier by chronically elevated insulin levels. Fasting insulin is, unfortunately, not routinely measured.
It’s clear: once insulin resistance has developed - meaning the body needs more insulin than normal to store the excess glucose - accessing fat reserves becomes much harder. And at that point, the advice to simply eat less doesn’t help either.
What does help is eating differently, so that insulin levels stay low, and the body can tap into its fat reserves. And that “different” way of eating is why I started this site in the first place.
…and that was just one of insulin’s effects on the body, Chapter 1. Later chapters will cover topics such as diabetes, high blood pressure, and more.