Key Takeaways

  • Intermittent fasting may help you to lose weight, improve insulin resistance and decrease blood pressure and inflammation
  • Angela Fitch, MD, FACP, FOMA, associate director of the Massachusetts General Hospital Weight Center, shares her strategies for using intermittent fasting to live a healthier lifestyle

Intermittent fasting (IF) is a potential way to lose weight and live a healthier lifestyle. IF is based on adjusting the timing of when you consume calories and when you do not, separating the day into a fasting period and a non-fasting period.

Angela Fitch, MD, FACP, FOMA, the associate director of the Massachusetts General Hospital Weight Center, shares the benefits of IF, how it works and her six Ps to living a healthier lifestyle and losing weight.

What is IF?

IF is an eating pattern in which you only consume calories during a specific window during the day. IF breaks the day into one fasting period and one eating period. There are many options for timing of the fasting period, or even fasting for a full day at a time. However, the most common method is fasting for 12-16 hours each day. For example, this could mean eating between 10 am and 6 pm and fasting for the remainder of the day.

One benefit of IF is its flexibility. If you wake up early and find yourself hungriest in the mornings, you can choose an earlier eating window. If you are a night owl or work late shifts, perhaps the evening is better for your eating window. Unlike many other popular diets, IF does not create rules around what you can and cannot eat. The only “rule” is that during fasting periods, you do not consume any calories. Only water, black coffee and tea are consumed during fasting time. 

IF may not be for you if you have an eating disorder, are pregnant or breastfeeding, have diabetes or are under 18 years old. You should consult with your physician if you have any of these conditions before trying IF.

How Does IF Work?

Glucose is the primary source of energy for the body and brain. Our body digests carbohydrates and breaks them down into glucose. Insulin stores that glucose in fat cells if it is not used.

When you fast for more than 12 hours, your body does not receive any glucose and therefore creates less insulin. IF works primarily by keeping insulin levels low throughout the fasting period, reducing how much glucose is transformed into fat. In a fasting period, the body becomes very efficient at utilizing fat for energy through the production of ketones, which supply energy for the brain. This results in reduced blood sugar and insulin levels, as well as reduced hunger.

The Six Ps for a Healthier Lifestyle and Weight

Dr. Fitch specializes in the treatment of obesity, internal medicine and pediatrics at Mass General. In a recent Facebook Live, she presented on IF and how it can be utilized to improve health and lose weight. Whether you are practicing IF or not, Dr. Fitch suggests following these six Ps for a healthier lifestyle and weight:

  1. Planned portions: Excess consumption is normalized in the U.S. today. To counteract these temptations in everyday life, it helps to plan out your meals and snacks. Planning can mean setting aside certain times to eat (via IF) or planning the contents and portions of those meals
  2. Plants: Consuming less processed food and eating more non-starchy vegetables and fruits such as berries, helps ensure you are getting enough essential vitamins and minerals in your diet as well as reduces inflammation
  3. Protein: Protein is needed to build muscle and for essential bodily functions. If you are practicing IF and not getting enough protein, try eating a protein bar or shake to increase your intake
  4. Power: Both exercise and fasting increase mitochondrial function, which helps burn energy. Practicing IF along with regular exercise maximizes this energy-burning benefit
  5. Pillow: Not getting the recommended 7 to 9 hours of sleep every night can slow your metabolism and lead to weight gain, insulin resistance and increase tendency to store energy as fat
  6. Pause: This is the act of fasting for a period of time and also pausing in your day to take time to reduce stress. Pause to practice meditation. Refrain from calorie intake for at least 12 hours as an initial goal

Dr. Fitch, who personally works toward following an IF lifestyle, explained that everyone is different, and there is not yet scientific research on how different body types react to IF. One of the great benefits of IF is that it does not place restrictions on what can and can’t be eaten. However, Dr. Fitch stressed the importance of cutting down on processed foods, which will enhance the health benefits of IF (or any diet you follow).

Related link: How to Make Intermittent Fasting Work for You