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Understanding Obesity

Normal Digestion

Dr. Jason Fung
7 min readMay 10, 2018

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All foods are composed of a combination of three major components, called macronutrients:

  1. Carbohydrates
  2. Protein
  3. Fat

Each of these macronutrients are composed of smaller functional units. Carbohydrates are chains of glucose and other sugars. Proteins are chains of amino acids. Fats (triglycerides) are chains of fatty acids. There are also smaller, microscopic amounts of vitamins (A, B, C, D, E, K etc.) and minerals (iron, copper, selenium etc.), known as micronutrients.

Digestion breaks down macronutrients for absorption into the bloodstream. This provides both energy (calories) and the raw materials needed (proteins, fats) to build cells. Certain macronutrients must be obtained from our diet because we cannot make them ourselves. There are called essential amino acids (such as arginine and leucine) and essential fatty acids (such as omega 3 and omega 6 fats), but there are no essential carbohydrates. Without these essential nutrients, we would get sick.

Each of the three macronutrients is metabolized differently. Carbohydrates, chains of sugars such as glucose…

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Dr. Jason Fung

Nephrologist. New York Times best selling author. Interest in type 2 diabetes reversal and intermittent fasting. Founder www.TheFastingMethod.com.