Intermittent fasting is likely something you’ve tried or heard of a friend trying. This weight-loss trend continues to gain a lot of attention for people looking to slim down. UC Davis Health Registered Dietitian Melinda Gong explains intermittent fasting and some of the pros and cons of the eating plan.

Where did fasting originate?

To clarify some definitions, fasting is purposely not eating food. In contrast, starvation is not being able to eat due to factors out of your control, such as food insecurity.

The origins of the practice of fasting date back to ancient times where it was a common practice to fast to help heal the body. It also has roots in religion where it’s said to help deepen your connection to your faith. One example is during the holy month of Ramadan where fasting is encouraged from dawn to dusk.

How does intermittent fasting work?

The idea behind intermittent fasting is that by restricting food, our bodies will more quickly and efficiently tap our fat stores for energy. While glucose from carbohydrates is our most direct fuel source, we burn fat for energy when glucose isn’t available. This happens even more during times of food deprivation. Our ability to store fat is unlimited.

Intermittent fasting can be done in a variety of ways. There’s no “perfect” fasting plan, and it really should be based on what works best in your life.

One method is fasting daily for a set amount of time, usually 12 hours or more. The average person sleeps about 7 hours a night, which counts towards that fasting time. If you don't eat after dinner, then you could easily achieve a daily fast to help your body burn fat more efficiently. This type of fasting could work well for someone who tends to be a nighttime snacker.

Another form of intermittent fasting is alternate day fasting. This is where you eat whatever you want 5 to 6 days of the week and choose 1 or 2 days a week to fast. During those fasting days, water and broth is encouraged so you don’t become dehydrated. This type of fasting could be beneficial for someone with a work schedule that may be really busy some days and cannot eat on a regular basis.

Remember: When you're eating, choose healthy foods such as fruits, vegetables, whole grains, lean meats, plant proteins, and non- or low-fat dairy products.

Is intermittent fasting right for you?

That question is difficult to answer. Overall, it’s important to determine why you want to try intermittent fasting, and what you hope to achieve. Is this something you plan to do forever?

Many people try fasting to lose weight, but if this isn’t something you can do forever – and if the plan isn’t sustainable – then you may regain that weight. Intermittent fasting can help with weight loss because it may help you eat less overall. This is especially true if you eat sensible portions and choose balanced meals during non-fasting times.

Take a moment to think about your eating habits. If you notice that you tend to snack a lot at night, intermittent fasting could give you a cut-off time and help you eat less. If you notice your last meal of the day is late in the evening, maybe you can eat earlier to allow your body to start fasting at that time.

What are other health benefits for intermittent fasting?

There is still not enough research on whether intermittent fasting can help manage chronic conditions. If you're thinking of intermittent fasting, check with your health care team first. Any type of fasting could be dangerous if you’re on certain medicines or have certain conditions. A health care provider can review your health history and provide you with guidance.

It's important to try methods that make you happy and don’t cause your mind and body harm. If following a set of rules of when you eat seems stressful, then intermittent fasting may not be right for you.

For more advice on nutrition, reach out to a registered dietitian to create a plan to help achieve your health and well-being goals.

Melinda Gong, RD CDCES CSOWM, is a registered dietitian at UC Davis Health. She is certified as a diabetes care and education specialist and a weight management specialist. She conducts health classes that focus on empowering people to self-manage their health. If you're interested in taking a class to learn more about nutrition or any other health condition, check out our Health Education Classes.