The Science Behind Intermittent Fasting: Fad or Fact

Julian Reiche
6 min readJun 13, 2014


Your trainer might be doing it, your friends are doing it and even that jacked guy at the gym is doing it there has been a lot of buzz building around intermittent fasting and were here to take down the lights and see if intermittent fasting is a fad or if there are some facts supporting this buzz. We all have heard of Fitness Fads before they are trends in the industry ranging from diets to exercise regimes that rocket into popularity only to fade into the distance. Unfortunately for many people Fitness Fads are analogues to scams and it is because of this that I hesitantly label Intermittent Fasting a Fitness Fad. As soon as something is label a fad many simply dismiss it meaning that while Friends and clients are shielded from the ridiculous claims of overzealous dieting evangelists, they may also lose out on the legitimate benefits of fasting done right.

What is Intermittent Fasting

For those just hearing of intermittent fasting it is fundamentally a dietary schedule that includes an unconventionally extended period of not eating or consuming very little. There are three prominent variations of this trend, there is the simplest 24 hour fast where you abstain from food for a full 24 hours once a week, commonly between 8am Sunday and 8am Monday. The remaining two methods are more popular including having two calorie restricted days where you consumer about 40% of your daily calories in a given week and most commonly having a 16 hour food free time, usually between 8pm and 12pm the following day.

Intermittent Fasting is supposed to facilitate weight loss by an overall reduction in calories consumed with proponents also claiming that it “promotes stronger insulin sensitivity and increased growth hormone secretion” that is supposed to make you leaner and grow larger muscles.

The touted benefits of Intermittent Fasting can be summarized in this quote by

From what I have read/learned from years of independent research on reduced calorie intake (CR) and IF (**studies listed at end), the conclusions are that using short-term calorie restriction/fasting may be effective when it comes to:

Reducing blood glucose and insulin levels (improving the state of the overall glucose metabolism)

Increasing fatty acid oxidation with increased FFAs (through increasing lipolysis hormones GH, glucagon and adrenaline)

Sparing and preserving muscle tissue (lean mass)

Increasing various health factors (lower inflammation, lower blood pressure, reduced oxidative stress, increased protection against neuro-degenerative diseases, and more)

Keeping the metabolism strong/healthy (as eating more meals does not “speed up” your metabolism)

What the Science Says

As with all fitness and diet programs it is important to be skeptical and separate the hype from the facts. To begin this dissection it is important to know that scientific knowledge is never derived from a single study or experiment, real scientific knowledge is only created after peer review and replication of the results by others. After all if intermittent fasting really works as many personal testimonies confess it too the results would be observable in labs around the world.

With that out of the way lets get into where exactly does intermittent fasting stands. While some scientists (particular Brad Pilon, author of Eat Stop Eat) might be evangelising the dietary pattern as a whole the scientific community current believes that yes intermittent fasting does deliver benefits (with a catch) but much more standardized research needs to be done.

Here’s the catch, of the available studies done that meet basic scientific standards they show that intermittent fasting can be a viable weight loss methods for overweight and obese people in the short term. But, Intermittent fasting has shown in only some studies that is can reduce blood glucose and insulin levels (which help you stay lean) but no more than a regular diet. Intermittent fasting however has been shown to increase meal satisfaction and over 12 week periods maintain meals satisfaction at lower caloric levels for obese individuals. For individuals within normal weight ranges that are otherwise healthy it is unclear if intermittent fasting has as many benefits, thus the call for more research.

In 2013 the Canadian Medical Association ran three stories covering Intermittent Fasting in which in one article titled “Intermittent fasting: The next big weight loss fad” does a fantastic job of presenting the current status of the feild. Dr. Stephen Freedland was interviewed in this piece because as an associate professor of urology and pathology at the Duke University Medical Center in Durham, North Carolina he studied the effects of intermittent fasting on prostate cancer tumour growth in mice. He describes how “To improve health, the goal should be to lose weight by reducing the total amount of calories consumed rather than focusing on when those calories are consumed. ”If you [don’t] eat two days a week, and limit what you eat the other five days, you will lose weight. It’s one approach to losing weight,” he says. “I’m not sure it works any better than cutting down slightly seven days a week.”” In short there is little scientific evidence published that differentiates intermittent fasting over other diets.

WARNING: A small minority of proponents behind Intermittent Fasting have gone as far to claim that because you eat less meals you preserve more stomach bacteria in your digestive system and thus can fight off “cancer” while living longer and staying healthier. This view is very outside of the mainstream with no rigours academic material being produced on the subject, it is best to treat this as snake oil until reputable studies are produced supporting this view.

The Risks

While it is proven that intermittent fasting is viable for weight loss in the same way reducing your daily caloric intake, there are also some risks associated with intermittent fasting that need to be considered.

Achieving weight loss and the associated health benefits with Intermittent fasting only happens when your global caloric intake is lowered. If you fast for 2 days or 16 hours but compensate for the missed calories during meals by binge eating you will not lose weight or attain any of the health benefits. Science studying the side effects of altering your dietary and sleep schedule has also shown that in the phase of transition, usually 1-3 weeks, peoples moods tend to be turbulent and varying AKA you will probably be a grouch and have mood swings.

Outside of the regular fitness warnings, if you have any medical history of pretty much anything or surgery/ injury you should not try any diet without consulting a licenced physician, intermittent fasting is also risky for women. Although in many studies obese women lost weight like men they did not experience the same benefits outside this and in the small number of studies done have shown women to suffer from long term fasting side effects much quicker than men.

So is it Something I Should Try?

From the small number of preliminary studies done so far it is safe to say that interment fasting as a diary pattern can be a viable short term weight loss strategy for normal weight/ overweight people that want to lose between 10-15 LB in about 12 weeks. Aside from this other benefits unique to intermittent fasting have yet to be proven scientifically and there are potential negative side effects of the diet. That being said if you are a healthy individual that wants to lose some weight intermittent fasting might be easier to integrate into your life style than reducing caloric intake at each meal.

Got a diet you want me to research of training technique email me at and I will add it to my schedule.

Prominent Sources

Collier, Roger. 2013. Intermittent fasting: The next big weight loss fad. Canadian Medical Association.Journal 185, (8) (May 14): E321-2, (accessed June 2, 2014).

Roky, Rachida, et al. “Sleep during Ramadan Intermittent Fasting.” Journal of sleep research 10.4 (2001): 319-27. Web. 2 June 2014.

Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial

*Through researching for this article I read many studies and quite a bit of literature on the subject, I have only provided sources for some of the prominent papers I came across



Julian Reiche

A passion for knowledge results in a lot of random facts.