What is Intermittent Fasting?
By Lydia Wallie, Nutritional Director
Intermittent fasting. To determine whether it's a good option for your health goals, it's important to understand what it is and how it works.
As a broad overview, intermittent fasting is taking periodic breaks from consuming most foods, gum, and beverages. The most common way to do intermittent fasting is with a 16 hr fasting window and an 8 hr eating window. A good example of this would be to fast from 8 pm through 12 pm the next day, and eat 2 meals between 12 pm and 8 pm.
Why might someone decide to complete a fast? Here are some of the impacts of fasting:
Improves bio-markers of disease
Reduces oxidation stress
Preserves learning and memory function
Fat stores are used for energy
Slows disease processes in the brain (1)
Improves insulin sensitivity
It’s associated with reduced body weight and total cholesterol (2)
Reduces inflammatory markers
Limits many risk factors for the development of cardiovascular diseases (3)
Benefits the microbiome (4)
Advice on how to fast
Eat quality foods. Intermittent fasting is not a permission slip to eat whatever you want within the eating window. Poor food quality leads to poor quality of life, and nutritious foods lead to better health and a better quality of life.
Do it gradually. If you jump all in from eating in a 16 hr window to only eating in an 8 hr window, your body might not be ready for this sudden shock. Try a more gradual approach with slowly going from a 16 hr eating window to a 15 hr window one day, and then a narrower window a couple of days later.
Listen to your body. Especially if you’re female, there are certain time frames within your menstrual cycle when your body is burning more calories, and it is more beneficial to pause intermittent fasting. Develop awareness of your hunger to notice when you may need to eat, rather than fast. It takes time to develop this awareness and intuition, but with time and intention, you will become more aware of noticing your body’s cues.
Try a fat fast. A fat fast provides a stable energy source without significantly raising blood sugar levels. (5) I find this approach to work well with busy lifestyles. Here’s how it works: Instead of doing a zero-calorie fast for the 16 hr window, consume a form of bulletproof coffee for breakfast (zero carbs and zero protein). This approach will keep your insulin levels low throughout the 16 hr fasting period, but it will also keep you energetic and satiated throughout the fast. A simple recipe for this is 12-16 oz of hot coffee mixed in a blender with 1-3 tsp of butter and coconut oil (start with 1/2 tsp and increase the amount of fat gradually over time).
Don’t purposefully restrict calories. Restricting calories has been shown to not be an effective long-term health or weight loss strategy. (6) The best strategy includes eating good quality foods, with healthy fat, protein, and fiber/carbs so that you’re full and nourished between meals and during the fasting period. In its best form, intermittent fasting is not a calorie reduction plan.
Come off the fast with balanced macros. It may be tempting to come off the fast with a large number of carbs, but this will cause a blood sugar spike. Instead, eat a balance of protein, fat, and carbs, so there isn’t a drastic spike in blood sugar.
Note: Fasting isn’t always a beneficial choice depending on the individual’s health. Always consult your physician before making any drastic dietary changes. If you are in the following life stages or have any of these health situations, it is recommended that you abstain from fasting: hormonal imbalances, pregnancy/breastfeeding, underweight, diabetes, elderly, history of eating disorders, or if you’re on medications requiring regular meals. (3, 7)
Source List:
(1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3680567/
(2) https://www.ncbi.nlm.nih.gov/pubmed/24739093
(3) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6471315/
(4) https://onlinelibrary.wiley.com/doi/full/10.1111/sji.12163
(5) https://www.ncbi.nlm.nih.gov/pubmed/9416027/