While diets focus on what to eat, intermittent fasting is all about when you eat. Intermittent fasting (IF) is a dietary pattern that includes extended periods of time during which one refrains from consuming any calories. Fasts may last, on average, from 12 to 24 hours.
As with any dietary regimen, intermittent fasting comes with both pros and cons. Some people practice intermittent fasting for its demonstrated role in supporting health and weight management goals. However, IF is certainly not for everyone. It can be impractical from a lifestyle perspective, posing challenges for family meals, busy schedules and workout routines. Plus, intermittent fating can be contraindicated from a medical standpoint.
Restricting food for periods of time can be dangerous and is not recommended for:
- children and teens
- people who are pregnant or nursing
- people with type 1 diabetes who take insulin
- individuals taking certain medications
- people with a history of eating disorders
Many IF experts believe that human body has evolved over time to function well without food for many hours. However, in modern times a typical eating pattern includes three meals and multiple snacks daily. Intermittent fasting prolongs the time period during which the body has already used the calories consumed at the last meal, thus is able to more effectively use body fat stores for energy.
Research on intermittent fasting has shown that it results in more than just fat loss. Some of the potential benefits of intermittent fasting include:
- reduction in fasting glucose, fasting insulin and leptin levels
- fat loss while maintaining muscle mass
- boost in verbal memory in human adults
- improvements in blood pressure, resting heart rate and cholesterol levels
If you are considering intermittent fasting, speak with your health care provider to make sure it’s right for you. Then, the next step is to determine which IF eating pattern to follow. Some popular intermittent fasting patterns are:
- Time-restricted eating. This pattern involves a fasting period of 12+ hours with eating occurring in the remaining hours during a 24-hour period. One of the more popular patterns is a 16/8 method, which includes fasting for 16 hours (some of these hours are during sleep) and eating within an 8-hour window. Time-restricted eating can be practiced one or more days per week depending on personal preference.
- The 5:2 diet. This diet involves eating normally for 5 days of the week and reducing calories as low as 500-600 during 2 days of the week.
- Eat: Stop: Eat. This pattern of IF involves a 24-hour fast maybe once or twice per week.
- Alternate-day fasting. This approach involves fasting every other day. “Fast” days would consist of low calorie intake of 25 percent of daily calorie needs while non-fasting days would include normal intake.
Although IF doesn’t focus specifically on what kind of food is consumed, eating a good variety of nutrient-dense food is very important while incorporating a fasting regimen. Closely monitor how you feel, your mood and other changes to continuously assess if your IF plan is right for you. While some hunger is to be expected when changing one’s eating schedule and implementing fasting, studies show that after a few weeks of IF, hunger levels are significantly reduced. Keep up communications with your health care provider to assess any potential changes in your health status.