Yeah, it's all metabolic -- sugar metabolism specifically.
When you eat refined sugars, they go directly into your blood stream, causing your blood sugar to spike. Your body deals with this by producing Insulin. This triggers your body to remove glucose from your blood by turning it into fat (and protein, and glycogen), and store it for later. It also suppresses your body's ability to release stored fat. [3] Each time you eat sugar, you body becomes physically incapable of burning fat. The more this happens, the more your body gets used to high levels of insulin (insulin resistance) which turns into Type II and eventually metabolic syndrome. [1, 2] The vast majority of Type II cases are dietary issues.
Your body has a well-defined hierarchy of what gets consumed first: (0) alcohol (1) carbohydrates (2) fats then last (3) proteins. [4] If you want to burn fat, you can't have carbs or alcohol around in meaningful quantities. Of the energy stores, dietary carbs are the only ones you don't need to survive -- your brain and red blood cells, I believe are the only part of you that requires them to live, and the liver/kidneys can synthesize all the glucose they need. [5] The rest of your body, including muscles, can operate solely on lipid metabolism. [6] In theory, anyways.
This, though, is the science behind Atkins and other fat/protein/ketosis based diets.
When you eat refined sugars, they go directly into your blood stream, causing your blood sugar to spike. Your body deals with this by producing Insulin. This triggers your body to remove glucose from your blood by turning it into fat (and protein, and glycogen), and store it for later. It also suppresses your body's ability to release stored fat. [3] Each time you eat sugar, you body becomes physically incapable of burning fat. The more this happens, the more your body gets used to high levels of insulin (insulin resistance) which turns into Type II and eventually metabolic syndrome. [1, 2] The vast majority of Type II cases are dietary issues.
Your body has a well-defined hierarchy of what gets consumed first: (0) alcohol (1) carbohydrates (2) fats then last (3) proteins. [4] If you want to burn fat, you can't have carbs or alcohol around in meaningful quantities. Of the energy stores, dietary carbs are the only ones you don't need to survive -- your brain and red blood cells, I believe are the only part of you that requires them to live, and the liver/kidneys can synthesize all the glucose they need. [5] The rest of your body, including muscles, can operate solely on lipid metabolism. [6] In theory, anyways.
This, though, is the science behind Atkins and other fat/protein/ketosis based diets.
[1] https://www.hsph.harvard.edu/nutritionsource/carbohydrates/c...
[2] https://en.wikipedia.org/wiki/Metabolic_syndrome
[3] https://science.howstuffworks.com/life/cellular-microscopic/...
[4] https://www.myvmc.com/anatomy/metabolism-and-energetics/
[5] https://en.wikipedia.org/wiki/Gluconeogenesis
[6] https://www.huffingtonpost.ca/mike-sheridan/carbohydrates-an...