What is Insulin and its function:
Insulin is a hormone produced in the pancreas which regulates the amount of glucose in the blood. The lack of insulin causes a form of diabetes.
The functions of insulin:
Controls blood sugar primarily by inhibiting *gluconeogenesis by the liver
Stimulates glucose uptake by muscle cells
Inhibits lipolysis (the release of free fatty acids from fat tissue)
Stimulates glucose uptake by fat cells
Stimulates free-fatty acid uptake by fat cells
Decreases the rate of fatty acid oxidation in muscle & liver
*is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates.
One of the topics that was presented by James Krieger at the Bropocalypse convention was the Carbohydrate/insulin hypothesis.
I want to share with you some of the predictions and then the data that James shared with us and why the carb/insulin hypothesis is actually a load of rubbish.
Gary Taubes is an American Author, Good calories and bad Calories. His main hypothesis is that carbohydrates stimulate the secretion of insulin which causes the body to store fat.
Here are some of Gary’s statements and subsequent arguments to that supported by data.
“...insulin plays a primary role in this fattening process, and the compensatory behaviours of hunger and lethargy...”
“...carbohydrates, and particularly refined carbohydrates...are the prime suspects in the chronic elevation of insulin; hence, they are the ultimate cause of common obesity.”
PREDICTION: If insulin is trapping fat in fat cells, then obese people should show reduced release of free fatty acids from fat tissue
THE DATA: Obese people show similar or elevated free fatty acid release from fat tissue as compared to lean people, despite having higher insulin levels.
PREDICTION: If insulin is trapping fat in fat cells, an oral or intravenous fat load should not significantly suppress lipolysis since insulin is not elevated
“As long as we respond to the carbohydrates by secreting more insulin, we continue to remove nutrients from our bloodstream in expectation of the arrival of more, so we remain hungry, or at least absent any feeling of satiation.
“It’s not so much that fat fills us up as that carbohydrates prevent satiety, and so we remain hungry.”
PREDICTION: If high insulin leads to hunger, then insulin injections at physiological doses that do not cause hypoglycemia should increase food intake
THE DATA: Insulin injections that do not cause hypoglycemia decrease food intake and body weight
Injection of insulin into the brain reduces food intake & body weight
Knocking out insulin receptors in the brain leads to overeating and increased body fat
Amylin, co-secreted with insulin, suppresses food intake & body weight
PREDICTION: If insulin spikes lead to hunger and weight gain, then drugs that enhance insulin spikes should result in weight gain
THE DATA: Exenatide (Byetta) enhances insulin spikes in type 2 diabetics yet improves satiety and causes weight loss
James Krieger provided around 26 falsified predictions for the carb/insulin hypothesis. He basically took down every statement Gary had made regarding insulin and obesity.
Take away points:
The carb/insulin hypothesis of obesity is a failure- CARBS DONT MAKE YOU FAT
There is no legitimate scientific reason to try to manipulate insulin levels through dietary means in the effort to modify body composition.
The low carb diets look to work not because they are low carb but usually because they are actually higher in protein. Check out my blog on protein
Obesity causes high insulin (due to insulin resistance), not vice versa
We have an obesity epidemic because we have decreased NEAT levels and over eating. A calorie surplus makes you fat.