This topic just keeps coming up. I know I have already covered this topic on the blog. More and more clients keep asking and I feel the need to add some more clarification. For the Blog post I will refer to intermittent fasting as IF. Did you know IF was a top 10 diet-related search on Google in 2018? Everyone thinks due to this hype they now need to be fasting. Now hear this! The current research is not so clear cut.

First of all there is no single definition for Intermittent fasting. It basically means restricting caloric intake for a certain period of time. Not very specific when it comes to research. Here are three common ways fasting is typically implemented:

Time-restricted feeding: Fasting 12 to 21 hours per day and having a specified eating window to consume food without restricting calories

Alternate-day fasting: Going a full day without eating

Modified fasting: Periods of extreme limited food intake (5:2 or 5 days normal eating, 2 days restricted intake)

Fasting can be a tool for weight loss but current research shows it is not necessarily any better than simply reducing calories. In fact current research shows it is NOT superior to calorie restriction in terms of weight loss.

So why is Intermittent fasting currently trending for weight loss? Why all the BUZZ?

When it comes to any nutrition plan, the reason people lose weight is more about caloric intake, awareness of food, mindful eating and portions than the specific dietary theory they are following. Intermittent fasting is just another dietary theory just like any other. Intermittent fasting is just one of many tools but isn’t necessarily superior for weight loss.

As I stated in the blog before, if it sounds like a good option for you, try it for 2 weeks and document how you feel. There is no singular solution for all. I did give this a go for a bit and have certainly utilized it for various days and activities. It doesn’t make sense for me on a 24/7/365 day a year plan. I try most days to not eat after 6pm, ( I go to bed early) so technically I am fasting each night 12-13 hours each night before my next meal.

Here are a few facts worth highlighting and possibly more important to your overall diet strategy when it comes to healthful nutrition. A 2019 a study found that people who eat a diet with more highly processed food end up eating approximately 500 more calories per day. The study suggested, “Limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment” (Hall et al, 2019). If you truly want to improve weight or health lets start be de-processing your diet and adding more fruits and veggies before moving to higher-level strategies like fasting.

Please note listed here are groups of people who should NOT fast:

Pregnant or breastfeeding women
Anyone a history of eating disorders or disordered eating habits
Diabetics and or people with low blood sugar
Women with a history of irregular periods, or trying to conceive

Conclusion: More Research is Needed
There is a lack of high-quality, large-scale controlled studies and data. Multiple definitions and methods for fasting, make it challenging to make recommendations from the current research. There currently is no long-term research studies that specifically investigate the impact of IF on men and women, it’s just too early to know the long-term benefits or drawbacks of fasting.

If it sounds good to you, give it a try. When asked by clients about my opinion on IF I will always remind them of the tried and true basic tenets of a healthy diet = consuming a variety “eating the rainbow” of whole, fresh foods, practicing portion control, taking twice the time to dine, reducing saturated fats and de-processing your diet. In doing so, you will improve your overall health and well-being over the long-term—not just the duration of a short-term diet.

References

Hall, K.D. et al. (2019). Ultra-processed diets cause excess calorie intake and weight gain: Cell Metabolism, 10.1016/j.cmet.2019.05.008.

Harris, L. et al. (2018). Intermittent fasting interventions for treatment of overweight and obesity in adults. JBI Database of Systematic Reviews and Implementation Reports,16, 2, 507-547.

Harvie, M. and Howell, A. (2017). Potential benefits and harms of intermittent energy restriction and intermittent fasting amongst obese, overweight and normal weight subjects—A narrative review of human and animal evidence. Behavioral Sciences,7, 1, 4.

Mcrae, M.P. (2017). Dietary fiber is beneficial for the prevention of cardiovascular disease: An umbrella review of meta-analyses. Journal of Chiropractic Medicine,16, 4, 289-299.

Seimon, R.V. et al. (2015). Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials. Molecular and Cellular Endocrinology, 418, 153-172.

Trepanowski, J.F. et al. (2017). Effect of alternate-day fasting on weight loss, weight maintenance, and cardioprotection among metabolically healthy obese adults: A randomized clinical trial. JAMA Internal Medicine, 177, 7, 930-938.