The body has three storage depots to use as fuel:
- Carbohydrates from food
- Protein that is converted to glucose in the liver and used for energy
- Stored body fat and ketones
In a regular high carb diet, carbohydrates are the main source of fuel for the body.
Carbohydrates, specifically starches and sugars are readily broken down into glucose in the bloodstream, giving the body its principal energy source.
At this point, the hormone insulin steps in to remove glucose from the bloodstream as too much sugar can lead to a dangerous condition known as glycosylation.
Insulin converts glucose into glycogen. Some glycogen is stored inside the liver as a fuel reserve for the brain, and the rest is stored in the muscles as fuel reserves for the body.
When that muscle glycogen is not used through a lack of energy expenditure or exercise, it stays in the muscles.
The human body can only store so much glycogen, about 1800 calories worth. When that reserve becomes full both the muscles and the liver send a signal to stop insulin production and excess glucose from dietary carbs begins to build up in the bloodstream, calling for more and more insulin to be released to remove it.
Insulin levels surge, and eventually this leads to insulin resistance.
At this point, the liver then sends any excess glucose to be stored as body fat.
As high carb intake continues, glucose floods the bloodstream, insulin levels increase, and so do the body’s fat stores.
Eventually this leads to metabolic syndrome, a set of conditions caused by insulin resistance, which includes obesity, fatty liver, type 2 diabetes, heart disease, and other metabolic issues.
While this carb cycle may not occur in everyone, for many who are obese, have a sensitivity to carbs, or who do not expend the required amount of stored energy, this is often the case and the main culprit behind obesity.