What happens when you eat carbohydrates
Carbohydrates provide energy (calories) with very little nutrition in return. When we focus on nutrient density and satiety, carbohydrates deserve the least attention. Why we recommend minimizing carbohydrates as a whole is largely due to the hormonal response to glucose. Glucose fluctuations are not only dangerous over the course of your lifetime but can affect our everyday life. Secondly, minimizing carbs typically means you are avoiding nutrient-poor foods.
What happens when we eat carbs?
When we eat carbohydrates, blood glucose levels rise. Regardless of source, all carbohydrates end up as glucose in the body (except for fiber). The body responds to elevated blood glucose levels by releasing the hormone insulin from our pancreas. Insulin is the fed-state hormone, inhibiting the breakdown of our own energy stores (e.g. body fat). This makes sense - why would we need to break down our fat if we have energy available? One of insulin’s primary jobs is to shuttle glucose from our blood and into our cells to be used for energy or stored as glycogen for later use. This is an incredible system that prevents high blood sugar levels, otherwise known as hyperglycemia, however read further and you will understand why this is not something we should take advantage of.
Glycemic Response to Food
A food’s ability to raise blood glucose is known as the glycemic response and is highly dependent on the quality and quantity of the carbohydrates eaten. This ultimately comes down to the source and processing of our food. Whole foods relatively low in carbohydrates and rich in fiber release carbohydrates slowly and produce a less dramatic rise in glucose, therefore releasing less insulin. Processed carbohydrates such as refined sugars, flours, and grains cause a more dramatic glycemic response, and trigger a large rise in insulin and a rapid fall in blood glucose, often lower than fasting levels. This puts you at risk for hypoglycemia which is attenuated by further feeding of carbohydrates – a vicious cycle. Just think about it this way - you don’t want your blood sugar on a constant roller coaster all day.
Factors that impact glucose response:
Level of processing - refined vs whole-food sources
Type of carbohydrate - starch vs sugar
Rate of consumption
More Glucose = More Insulin = More Problems
Problems arise when the pancreas has to constantly respond to carbohydrates – continuous feeding of refined carbohydrates, continuously high blood sugar levels, and the continuous release of insulin. When our cells are overexposed to insulin, they gradually stop responding to it and require more of it to transport the same amount of glucose. The pancreas has to work overtime to keep up with the constant influx of glucose and over time this can lead to insulin resistance, obesity, and Type-2 Diabetes.
We know now that chronically elevated insulin is associated with many conditions beyond those mentioned above. Insulin and impaired glucose metabolism plays a role in the development of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, among others . Additionally, elevated glucose and insulin levels are known contributors the growth and spread of cancer .
Glucose, Insulin, and Appetite
Satiety is something we always come back to when considering what foods to eat. Glucose and insulin play major roles in regulating our appetite, especially for those who are metabolically inflexible, meaning they have limited to no capability of using their own body fat for fuel when glucose levels drop. Remember, humans are fat-burners - we want to rely on fat as our primary fuel source. Constantly eating carbohydrates (which turn to glucose in our bodies) continues the reliance on sugar-burning instead of fat-burning. Glucose is the fast-acting fuel, while fat is the slow-and-steady fuel. Like marathon runners are dependent on packs of sugary goo every few hours for energy, if you rely on this quick source of energy, you too will be searching for food every few hours.
Low glucose levels can alter perceived hunger and promote the vicious cycle of consuming carbohydrates as we mentioned above. When we are dependent on carbohydrates, it is almost like we are a slave to food where our energy levels are governed by how often we eat. This promotes frequent eating, and the way we see it, the more frequently you eat, the greater the chance of over-eating. In fact, the science shows that hunger returns earlier when eating high-carbohydrate meals vs low-carbohydrate meals and that this is associated with a rapid postprandial rise and fall in blood glucose .
While carbohydrates themselves shouldn’t be demonized, flours, sugars, and other refined carbohydrates offer virtually nothing to the body. So, you can still order the burger, just skip the bun (and fries & soda)! Reducing fluctuations in blood glucose and insulin is just one way replacing carbohydrates with proteins and quality fats offers greater satiety and better regulate our appetite.
Craft S, Watson GD. Insulin and neurodegenerative disease: shared and specific mechanisms. Lancet Neurol. 2004;3(3):169-178.
Orgel E, Mittelman SD. The links between insulin resistance, diabetes, and cancer. Curr Diab Rep. 2013;13(2):213–222.
Chandler-Laney PC, Morrison SA, Goree LL, et al. Return of hunger following a relatively high carbohydrate breakfast is associated with earlier recorded glucose peak and nadir. Appetite. 2014;80:236–241.