Alternate Day Fasting, Exercise, and NAFLD

Nonalcoholic fatty liver disease (NAFLD) is characterized by an accumulation of fat in the liver (not resulting from excessive alcohol consumption). Approximately 65% of obese individuals have NAFLD, and this condition is strongly related to the development of insulin resistance and type 2 diabetes. While certain pharmacological agents have been shown to reduce liver fat (i.e. thiazolidinediones), there is mounting concern regarding the safety and weight-gaining effects of these compounds. In light of this, recent research has focused on non-pharmacological lifestyle therapies to reduce hepatic steatosis, such as daily calorie restriction combined with aerobic exercise. Evidence from clinical trials suggest that this combination is an effective lifestyle therapy improve liver fat content and hepatic insulin sensitivity.

More recently, it's been shown that intermittent fasting may produce even greater improvements in hepatic steatosis and hepatic insulin sensitivity, when compared to conventional calorie restriction. For instance, intrahepatic lipid accumulation was lower and insulin sensitivity was higher in mice fasted every other day, when compared to mice who were energy restricted every day. Moreover, data from human trials show that adults with obesity experience greater decreases in insulin and insulin resistance with intermittent fasting versus daily restriction. These findings suggest that intermittent fasting may be a more effective diet therapy to reduce hepatic steatosis and improve insulin sensitivity, when compared to daily calorie restriction. Although these findings are very promising, these data still require confirmation by a randomized controlled clinical trial.

Inclusion criteria

• Age between 18 to 65 years old
• BMI between 30.0 and 59.9 kg/m2
• NAFLD (hepatic steatosis ≥ 5% confirmed by MRI-PDFF)
• Sedentary (<20 min, 2x/week of light activity at 3-4 metabolic equivalents (METs) for 3 mo prior to study)

Exclusion criteria

• Have chronic liver disease other than NAFLD (hepatitis B or C, primary biliary cirrhosis, sclerosing cholangitis, autoimmune hepatitis, hemochromatosis, Wilson's disease, α1-antitrypsin deficiency)
• Consume excessive amounts of alcohol women: 70 g of ethanol (5 alcoholic drinks per week) and men 140 g of ethanol (10 drinks per week) in the past 6 months)
• Have a history of known cardiovascular, pulmonary or renal disease
• Diagnosed T1DM or T2DM
• Are not weight stable for 3 months prior to the beginning of study (weight gain or loss > 4 kg)
• Are claustrophobic or have implanted metallic/electrical devices (e.g. cardiac pacemaker, neuro-stimulator)
• Are taking drugs that induce steatosis (e.g. corticosteroids, estrogens, methotrexate, Ca channel blockers)
• Are taking drugs that benefit NAFLD (e.g. betaine, pioglitazone, rosiglitazone, metformin, or gemifibrozil)
• Are taking drugs that influence study outcomes (weight loss medications)
• Are perimenopausal or have an irregular menstrual cycle (menses that does not appear every 27-32 days)
• Are pregnant, or trying to become pregnant
• Are smokers