Does a large carbohydrate meal make you gain weight from eating too much?
Okay, we have all heard this in some form or another. When you eat a large meal heavy on the carbohydrates, it causes a spike in blood sugar. This causes an overreaction in insulin production leading to a reduction in blood sugar, but then overshoots in the other direction causing a low blood sugar several hours after the meal.
This scenario goes on to posit that this low blood sugar condition leads to a “crash” where we feel tired and lethargic, and that feeling leads us to feel hungry in order to “refuel” our blood sugar. Logical, right? It makes so much sense it has to be true.
Maybe not! It turns out when this is actually put to a scientific study it cannot be verified. Oh, there is no doubt that the blood sugar crash is real, and the crash we feel is also. However, the connection between that and the desire to eat more may not be a reality.
Is the carbohydrate crash just an urban legend?
Stephan Guyenet is an obesity researcher, neurobiologist, and author with a BS in biochemistry (University of Virginia) and a PhD in neurobiology (University of Washington). Stephan writes articles at his website WholeHealthSource.com, a free resource for anyone who loves the science of health.
I am linking below to an article written by Stephan titled “Do Blood Glucose Levels Affect Hunger and Satiety?”. In this article, Stephan reviews a study which looked at the “blood sugar crash” from a high glycemic “meal” and the effects on hunger levels.
It turns out that as expected blood sugar did “crash” to a much reduced level an hour after a glucose injection simulating a high glycemic meal compared to the control group receiving no glucose. However, there was no difference in hunger levels between the glucose group and the control group – so much for the urgent need to eat again in response to the “carbohydrate crash”.
Stephan goes on to discuss why this may be the case, here is a quote from the article with part of the answer:
The brain listens to a variety of signals that indicate the body’s energy status, and it integrates these signals to determine your sensation of hunger or satiety (7). Glucose is one of the signals the brain listens to, but there are many others, and the brain doesn’t appear to pay very much attention to the glucose signal when it’s within the range that occurs in the daily life of most people. In contrast, the brain pays attention to levels of leptin, CCK, GLP-1, glucagon, amylin, ghrelin, and signals ascending from the gut via the vagus nerve (7).
Of course, this is no reason to go hog-wild on carbohydrate again. The fact still remains that a higher carbohydrate diet leads to too much blood glucose and a cascade of health issues such as insulin resistance which often result in obesity and diseases related to metabolic syndrome.
I find it interesting how much of what we “know” about diet, nutrition, and health is in reality these myths which have been repeated so often that they are accepted as truth. Avoiding saturated fats because of cholesterol and heart disease may be one of the most glaring examples of this, but there are indeed many we labor under.
Thank goodness for the internet – which makes science available to everyone to discover through the work of researchers like Stephan.
Enjoy the article.