Non-alcoholic fatty liver disease occurs when excess fat is stored in your liver. The most common cause of liver disease used to be alcohol, but now it is far more likely to be caused by eating sugar-added foods and drinking anything with sugar in it. Up to 12 percent of people with fatty livers keep on adding fat to their livers to develop Non-Alcoholic Steato Hepatitis (NASH), which is liver inflammation and permanent liver damage called cirrhosis and can cause liver cancer (Gastroenterology, August 23, 2018). The simple sugar, fructose, is the most likely food component to end up as fat in your liver (Dig Dis Sci, May 2016;61(5):1282-93).
How Does Sugar Cause a Fatty Liver?
After you eat, your blood sugar level rises, which causes your pancreas to release insulin, which converts the sugar to a type of fat called triglycerides. To prevent your blood levels of triglycerides from rising too high, your good HDL cholesterol is used to carry triglycerides to your liver where they are stored to cause a fatty liver.
High levels of triglycerides (>150) predict diabetes and in diabetics, high triglycerides predict increased risk for premature death (Diabetes Care, 2017;40(4):529-537). The more fat you have in your liver, the higher the rise in blood triglycerides after you eat (Clin Sci (Lond), Sept 18, 2017). People who eat a lot of foods with added sugars have more than double the risk of heart disease than those who eat the least (Am J of Clin Nutr, April 7, 2010; Arch of Int Med, May 2010).
Why Sugared Drinks Cause Such High Rises in Blood Sugar
When you take in liquid sugar, you get a much higher rise in blood sugar than when you take in the same amount of sugar in a solid food. Solid foods stay in your stomach until they are converted into a liquid soup, while liquids can pass directly into your intestines, so sugared drinks cause the most rapid passage of sugar into your intestines and the highest immediate rises in blood sugar. Compared to sugar in food, sugar in drinks is more strongly associated with increased risk for excess belly fat (Circulation, January 11, 2016; Quart J Med. Apr 26, 2017), obesity (Nutr J, Aug, 2017;22;16(1):48), and diabetes (Am J Clin Nutr, Jun 28, 2017; Curr Opin Cardiol, Sept, 2017;32(5):572-579). All sugar-sweetened beverages are associated with a significantly increased risk for developing a fatty liver and metabolic syndrome, which is also called pre-diabetes (Int J Clin Pract, Jan 10, 2017)
How a Fatty Liver Causes Diabetes
Your blood sugar level is supposed to rise after you eat. To prevent your blood sugar level from rising too high, your pancreas releases insulin which is supposed to lower high blood sugar levels by driving sugar from the bloodstream into the liver. However, if your liver is full of fat, the excess fat prevents the liver from accepting the sugar and blood sugar levels can rise higher and higher. Many diabetics or prediabetics will have "normal" fasting blood sugar levels below 100 mg/dl (In Canada and UK, convert to the U.S. number by multiplying the Canadian or UK number by 18). The correct definition of diabetes is having a rise in blood sugar one hour after a meal to more than 140 mg/dl (Diabetes Care, 2001;24 (8):1448-1453).
How Can You Tell If You Have a Fatty Liver?
You are likely to be at high risk for a fatty liver and diabetes if you have a big belly and small hips. People who store their fat primarily in the belly are also prone to storing fat in the liver. Your doctor can do a liver sonogram to determine whether you have excess fat in your liver (Nutrition, Metabolism & Cardiovascular Diseases, Dec 30, 2015).
How Do You Get the Fat out of Your Liver?
Exercise: Exercise can markedly reduce the amount of fat in your liver (World J Gastroenterol, Jul 21, 2016;22(27):6318-27). It does so by lowering blood sugar which then lowers triglycerides, the fat that forms in your liver (J of Funct Morph and Kines, 2017;2(4):35). Resting muscles draw almost no sugar from your bloodstream and the little that they do draw requires insulin to do so. On the other hand, contracting muscles draw tremendous amounts of sugar from the bloodstream and don't even need insulin. This effect that exercise has of rapidly drawing sugar from the bloodstream is maximal during exercise and for up to an hour after you finish exercising and rapidly tapers off after 17 hours. Then muscles can draw sugar only with insulin (Am J Clin Nutr, 2008(July);88(1):51-57). Exercise reduces liver fat even if a person does not lose weight (Metabolism, Mar 2017;68:119-132).
Diet: Avoid foods that cause a high rise in blood sugar, such as all sugar-added foods and all drinks with sugar, including fruit juices. Restrict other refined carbohydrates such as foods made from flour. Most people with a fatty liver are overweight and will need to lose weight to get the fat out. I recommend intermittent fasting.