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Fasting involves limiting food intake for a period of time. Intermittent fasting, including "time-restricted feeding", has become a common dieting strategy.

Intermittent fasting involves eating very little for a short period of time. This might mean that fasting occurs for 12-16 hours each day, for 1-2 days per week, or every other day. Normal eating takes place during the rest of the day or week. This approach is sometimes used as a dieting strategy because it can reduce the total amount of calories that a person eats over time. This may lead to weight loss and other health benefits.

People use intermittent fasting for metabolic syndrome and obesity. It is also used for athletic performance, aging, diabetes, heart disease, epilepsy, and other conditions, but there is no good scientific evidence to support these uses.

NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
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  • Metabolic syndrome.  Intermittent fasting for 2-4 months appears to improve body weight and waist circumference in patients with metabolic syndrome. It is unclear if fasting improves cardiometabolic parameters.
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  • Nonalcoholic fatty liver disease (NAFLD).  Several small clinical studies suggest that intermittent fasting might improve body weight, liver enzyme levels, and measures of fibrosis and steatosis in patients with NAFLD.
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  • Obesity.  Intermittent fasting seems to be beneficial for weight loss in adults with overweight or obesity. However, it is unclear if intermittent fasting is more beneficial than continuous energy restriction.
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Intermittent fasting is possibly safe when used appropriately, short-term. It has been practiced for up to 12 months with no serious side effects. The safety of intermittent fasting when used longer than 12 months is unclear.

Complete, water-only fasting is possibly safe for up to 22 days under medical supervision. But complete fasting is likely unsafe when done without medical supervision. This may lead to serious health issues and even death.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if fasting is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid fasting.


Interaction Rating=Moderate Be cautious with this combination.

Fasting can lower blood sugar. Insulin is also used to lower blood sugar. Fasting while using insulin might cause your blood sugar to be too low. Monitor your blood sugar closely. The dose of your insulin might need to be changed.

Medications for diabetes (Antidiabetes drugs)

Interaction Rating=Moderate Be cautious with this combination.

Fasting might lower blood sugar levels. Fasting while taking diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Moderate Be cautious with this combination.

Fasting might slow blood clotting. Fasting while taking medications that also slow blood clotting might increase the risk of bruising and bleeding.

Warfarin (Coumadin)

Interaction Rating=Major Do not take this combination.

Warfarin is used to slow blood clotting. Fasting while taking warfarin might increase the effects of warfarin. This might increase the chance of bleeding. Be sure to have your blood checked regularly. The dose of your warfarin might need to be changed.

There are no known interactions with herbs and supplements.

There are no known interactions with foods.

Fasting practices vary. The most common types of fasting are called "intermittent fasting". These include alternate-day fasting, periodic fasting, time-restricted feeding, and religious fasts. Some people also follow longer fasts under medical supervision.

Alternate-day fasting involves alternating between fasting for one day then eating food as desired the next day. Periodic fasting involves fasting for 1-6 days per week then eating food as desired for the remainder of the week. Usually, fasting is for 2 days each week. Time-restricted feeding involves eating only during a certain time period each day. Religious fasts such as the Ramadan fast involve fasting from sunrise to sunset for one month.

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