Intermittent fasting (IF) and its metabolic effects are the most recent news flash to hit the diabetic research community. It is a practice evangelized by many people including Dr. Jason Fung in his book The Diabetes Code. What exactly is it? How does it work? Is it safe?

The basics

IF, also called time-restricted feeding, is when you restrict the time during the day when you can eat. During the time that you are not eating, you may drink water, coffee, tea, or broth. Some practitioners allow themselves a small number of calories during the fast. Halebee recommends that you talk to your doctor about fasting BEFORE you try intermittent fasting. While it is generally considered safe for short durations, hypoglycemia is possible if you are taking medication for your diabetes. Be sure to monitor your blood sugar level regularly while fasting.

There are several flavors including: alternate-day fasting, periodic fasting, time-restricted feeding, and religious fasts. A few common variants are described below:

  • 16:8 method asks you to fast for 16 hours of the day and only eat during 8. It is also known as the Leangains protocol. Typically this involves skipping breakfast and only eating lunch and dinner.
  • 5:2 method you consume 600 calories 2 nonconsecutive days during the week, but eat normally the other 5 days.
  • Alternate-day method allows you to eat one day and fast the next. You can drink calorie-free beverages you want during the fast days of the week.
  • Eat-Stop-Eat method involves fasting for 24 hours 1 or 2 nonconsecutive days per week.

Practicing IF will likely reduce the overall number of calories you intake – leading to weight loss. It will also lower the amount of insulin in your blood by increasing the time between meals. This may effectively reduce your fasting blood sugar! Whichever model of IF you try, prediabetes and people with T2DM may see good results. Today there are so many mobile apps that have been developed to help you fast.

A personal story

About 5 years into my T2DM journey, my HbA1C level started to go up dramatically and I noticed that my morning blood sugar levels were very high. My doctor wanted to add a third medication, because Metformin + Glipizide were no longer controlling my blood sugar level well. I decided to try the 16:8 method of IF. I’m a morning person, so I would eat breakfast by 8am and lunch around noon, but I would have a small dinner or snack before 3pm and no dinner. It took some time to get the hang of it, but over the course of 2-3 months I was able to bring my HbA1C back down to 7.1 and my doctor agreed that I did not need to add a 3rd medication. It does take a mental adjustment to get acclimated, but I decided to eat breakfast and skip dinner because I’m always hungry in the mornings and I realized my morning blood sugar level was lower if I skipped dinner.

–Suzi Soroczak, CEO of Halebee

The current research on intermittent fasting

A review of research by Patterson and Sears (2017)1 detailed the following talking points (page 386-387):

  1. Data from human studies are limited regarding the positive impacts of time-restricted feeding (i.e., eating patterns aligned with normal circadian rhythms) on weight or metabolic health. However, animals studies support the hypothesis that IF and restricting the availability of food improves metabolic profiles and reduce the risks of obesity and obesity-related conditions, such as nonalcoholic fatty liver disease, diabetes, and cancer.
  2. Overall, evidence suggests that intermittent fasting regimens are not harmful physically or mentally (i.e., in terms of mood) in healthy, normal weight, overweight, or obese adults.
  3. It appears that almost any intermittent fasting regimen can result in some weight loss. Among the 16 intervention trials included in this review, 11 reported statistically significant weight loss.
  4. Alternate-day fasting appeared to result in weight loss, as well as reductions in glucose and insulin concentrations, in the three studies evaluating this regimen.
  5. Research has not demonstrated that alternate-day fasting regimens produce superior weight loss in comparison to standard, continuous calorie restriction weight-loss plans.

Due to the excitement around this approach and the mixed results in research, I expect to see more research about the metabolic effects of intermittent fasting in the near future. This research area is ripe for data on herbal clients who may want to try an intermittent fasting regime to improve their glucose control and to lose weight.

Is it right for you?

Fasting may bring health benefits, but not eating can be dangerous for some people. Talk with your health care provider first, especially if you:
» Are under the age of 25.
» Are pregnant or breastfeeding.
» Have been prescribed any medication that must be taken with food.
» Have a seizure disorder.
» Work the night shift or operate heavy machinery at your job.


  1. Patterson, RE & Sears, DD (2017) Metabolic effects of intermittent fasting. Annual Review of Nutrition 37: 371-393.
  2. Welton, S., Minty, R., O’Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermittent fasting and weight loss: Systematic review. Canadian family physician | Medecin de famille canadien, 66(2), 117–125.
  3. A closer look at fasting diets