Intermittent fasting: Can it really give you diabetes?


Intermittent fasting tends to be talked about in terms of when you eat being more important than what you eat. Photo: Getty
Surely these are the two most contested questions in human history: Is there an all-seeing God? And does intermittent fasting help you lose more weight than counting calories?
To an extent, in both cases – until the evidence is overwhelming, one way or the other – it comes down to a question of belief.
The argument over intermittent fasting arguably makes more noise.
As researchers battle it out (presumably in good faith) with competing studies, the media further complicates the question with how it reports on new research.
By way of example of how messy it gets, this week, there were two stories widely published about intermittent fasting and type 2 diabetes.
The issue of intermittent fasting’s impact on type 2 diabetes – call it a subplot – is an industry all on its own.
We’ll get back to that.
What is intermittent fasting?
Intermittent fasting is the almost cult-like strategy – being subscribed by well-built celebrities – for losing weight and improving metabolism.
In fact, there’s growing evidence that intermittent fasting has a range of heath benefits, including reduction of oxidative stress and inflammation in the body. It also appears to induce cellular repair. Read more here.
Intermittent fasting is also known as ‘time-restricted eating’.
It’s often described as being more about when you eat more than what you eat. And intermittent fasters, when they get around to eating, tend to have the idea they can eat whatever they want. Which is nuts.
Intermittent fasting (IF) involves restricting your eating to a few hours a day or a few days of the week.
This type of fasting can involve eating no food at all, or eating a small number of calories per day.
One example is the 16:8 diet, which involves eating only during an eight-hour daily window and fasting for the remaining 16 hours. This is probably the least arduous version to follow.
Another is the 5:2 diet, where you eat ‘normally’ five days a week, and eat nothing or almost nothing for two days.
Alternate-day fasting where you eat one day, and fast the next.
For other versions, see here.
For every study that says IF is more effective than good old calorie counting, another finds this isn’t true. One may be just as effective as the other.
See this New York Times report about a true-believer scientist who personally abandoned IF after conducting a large study.
What were the diabetes stories about?
In one story, pounced on by tabloids, intermittent fasting could give you diabetes. In the way, perhaps, that a drunken kiss might give you a cold sore.
This was somewhat misleading: the story was based on a large, interesting study that found if you ate late at night (which is bad for you regardless) or had a late breakfast, you might develop diabetes.
The actual study wasn’t really about of intermittent fasting, but circadian rhythms. More simply, it was about eating at different times of the day.
Science Daily ran a media release from the researchers which said:
Eating an early breakfast might in fact protect you against developing type 2 diabetes.
This was the main conclusion of the study, which is supported by other research.
In April, a University of Adelaide study found, “A fasting diet which focuses on eating early in the day could be the key to reducing the risk of developing type 2 diabetes.”
The Adelaide study was “one of the largest … in the world to date”.
There is, in fact, mounting evidence that IF protects against type 2 diabetes.
The second story
In the second story, reporting on a new study, people with type 2 diabetes were found to lose more weight with intermittent fasting than with old-fashioned calorie counting.
This wasn’t news. In the last couple of years, a number of studies have found that IF was effective in type 2 diabetes patients who wanted (needed) to lose weight.
More than that, multiple studies have found that a program of IF can tip type 2 patients into full remission, where they no longer need to take medication. In one study, 90 per cent of participants went into remission. See here and here.
As much as this is promising, it’s also complicated. For example, different versions of intermittent fasting can have different effects on people.
A 2018 study found that fasting every other day (alternate-day fasting) impairs the action of sugar-regulating hormone, insulin, which may increase diabetes risk.
IF isn’t for everybody, and for some people with type 2 diabetes it’s not a good option. Why? Because they may be at risk of hypoglycemia and hyperglycemia.
This is due to fluctuations in blood sugar during and after periods of not eating. And this largely comes down to what medications people are taking.
The take-away
Based on the evidence so far, intermittent fasting appears to work as well as old fashioned calorie counting for losing weight.
In fact, IF is a form of calorie-restriction.
Intermittent fasting, particularly the 16:8 version might appeal because it’s easy to follow.
But it appears that not enough attention is paid to what you should be eating on an intermittent fasting plan, as to when.
There are no free lunches, so to speak. Lots of fruit and vegetables, nuts and seeds, beans and legume, whole dairy and whole grains, and fish more than meat is the way to go, no matter what time of day you’re tucking in.