Intermittent Fasting Q&A

Intermittent fasting may be one of the most discussed and researched diet and nutrition trends. But what does it mean? How does it work? And who should — and shouldn't — consider it?

Fellowship trained in obesity medicine, Shawn Day, DO, of CentraCare Weight Management, talks about taking a pause from eating during one's day.

What is intermittent fasting?

Dr. Day: Intermittent fasting is the voluntary avoidance of food for health, spiritual or other reasons.

What are the different types of intermittent fasting?

Dr. Day: There are two primary fasting methods: "alternate day" and "timed nutrition window."

Alternate day fasting usually refers to a pattern of eating that is regular for some days and only 0-500 calories per day on others. For example, a 5-2 fast would mean that an individual eats regularly five days a week and "fasts" by eating 0-500 calories/day on two days per week.

A timed window strategy is a fast with an 8- to 12-hour window of food intake each day. For example, a 16:8 fast may include fasting from 7 p.m. until 11 a.m. The period between 11 a.m. and 7 p.m. would include all meals.

Do you recommend fasting?

Dr. Day: CentraCare Weight Management will occasionally recommend the timed window strategy. However, for us, the more important goal is to establish an eating structure. Our bodies respond to structure. A structured, consistent, eating pattern ensures the body is properly nourished and obtains adequate calories to support weight loss.

In cases where we recommend timed nutrition window fasting, it is most common with someone who already postpones a first meal until later (11 a.m./noon). We would recommend the person "formalize" this eating pattern by establishing a "routine" of timed window eating from noon to 7 p.m.

CentraCare Weight Management does not routinely recommend alternate day fasting, water fasts or other types of fasting. They are usually not sustainable and are really hard to maintain generally — with no greater benefit. You would need to be working with someone such as a doctor or registered dietitian if utilizing this type of eating plan.

Is there a best time (of day) to place a timed window of eating?

Dr. Day: No. The key to a successful timed window of eating is a consistent eating pattern with no between meal eating. Choose non-calorie beverages and choose a variety of foods and food groups for your meals.

Is timed window eating safe for me?

Dr. Day: While timed window eating and other versions of intermittent fasting have benefits, there is still a safety risk for some people. Discuss any plans to include intermittent fasting methods with your doctor.

Who shouldn't try timed window or intermittent fasting?

Dr. Day: People who should NOT fast include those who are underweight, have an eating disorder, women who are pregnant or breastfeeding, and people under the age of 18.

Is it OK to exercise while using an intermittent fasting strategy?

Dr. Day: Yes. You can continue all your usual activities, including exercise.

Who can most benefit from intermittent fasting strategies?

Dr. Day: Individuals who are interested in losing weight, lowering blood pressure, reducing cholesterol and improving blood sugar may benefit from intermittent fasting strategies.

What are the other possible health benefits of intermittent fasting strategies?

Dr. Day: Purported health benefits of intermittent fasting may include:

• Weight and body fat loss
• Increased fat burning
• Lowered blood insulin and sugar levels
• Improvement of type 2 diabetes
• Improved mental clarity and concentration
• Increased energy
• Improved blood cholesterol profile
• Longevity
• Reduction of inflammation

How long can I expect to wait before I experience the benefits from intermittent fasting strategies?

Dr. Day: Benefits can be very individualized. Some may be experienced within days of starting an intermittent fasting plan.

Should I be worried about potential negative impacts of meal skipping on my blood sugar levels?

Dr. Day: Meal skipping could cause blood sugars to decrease. If you have diabetes mellitus type 1 or type 2 or if you are on any prescription medications, you should consult with the provider managing your diabetes and any medication, including obesity medication, before engaging in intermittent fasting strategies.

Why does CentraCare Weight Management occasionally recommend timed window eating strategies?

Dr. Day: For many, a timed window of eating strategy can be followed lifelong. Our goal is to partner with our patients to create health, and occasionally a timed window of eating strategy is useful to bring structure to an eating pattern.