I’ve now been dieting in one way or another for the majority of my adult life. The majority of my entire life, really. I can remember the first time I really went “on a diet”: I was 16, I’d tried various healthy eating habits before and nothing really worked. I exercised fairly regularly — I cycled the 6km to and from school daily — but was still depressingly chubby.
So, I tried dieting.
The first step was to see a dietitian, who told me all of the things I was doing wrong and left me with a perpetual feeling of guilt whenever I drink sweet drinks that persists to this day. If you’ve tried guilt as a motivation tool for dieting you’ll be unsurprised to know that it didn’t work. If anything, quite the opposite; over the next few years I exercised less and less, and ate more and more despite my various attempts to slough off the kilos.
Eventually, I managed to change my life.
It was hard. Years of effort, changing jobs, moving house, daily struggles with unhealthy food: the works.
What if there was an easier way?
Occasionally starving ourselves to lose weight is not a particularly new idea. There have been people promoting intermittent fasting for decades, with many claiming that it has an amazing effect above and beyond the calories that you restrict and actually might change your body chemistry so that you lose weight better.
Which brings us to the fancy new study that was just released. According to a number of headlines screaming across the world, scientists have just discovered the key to losing weight quickly. As you may have guessed, the key is intermittent fasting.
Not only will this amazing technique help you to lose weight, it improves blood pressure, gut health, and can even stop you from getting cancer!
I can hear the click-bait “Try This One Simple Trick” articles being written now.
The only problem?
The best evidence says that intermittent fasting doesn’t work.
Weight-Loss For Rodents
“But what about this new study?” I hear you say, “The one that has all the newspapers telling me to starve on weekends to drop those ice-cream heavy pounds?”
The problem, dear reader, is that this study doesn’t prove much about fasting for you. It doesn’t prove much about fasting for anyone.
Because it was done in mice.
“Testing an intermittent fasting regimen in an animal model is very different from what is practical and safe for humans.”
Basically, this study found that there were metabolic changes when mice were forced into a diet mimicking a human who would be intermittently fasting. These changes were fascinating, and may indicate that more research needs to be done to see exactly what changes when people try these diets.
But the bottom line is that mice aren’t people.
Mice are a great model, allowing us insight into what could happen to people, what might be true when humans do something. But you can’t take a rodent study and say that “Fasting after every two days may help fight obesity” or that “Intermittent Fasting Boosts Fat Burning and Improves Metabolic Function”. These results may not mean anything at all to people, particularly in the real world, outside the controlled conditions of a lab.
So what is the best evidence about intermittent fasting, on people and in the real world?
It turns out that there isn’t a great deal. In 2016, a group of researchers did what is known as a systematic review, looking at all of the evidence that has been produced around intermittent fasting to see if it worked. After looking at 1,000 studies, they found that intermittent fasting did lead to an average weight loss — it was reasonably significant at around 7kg per person — but was no difference in effect to any other method of dieting*. This agrees with previous research, which has found that not only does intermittent fasting not do better than other forms of weight management, it may in fact be less sustainable in the long term. This is partly because people experience uncomfortable side-effects when they don’t eat for days.
In other words, intermittent fasting doesn’t work. At best, it may be as good as any other method of reducing calories.
All those headlines touting the benefits of this new diet fad were wrong. These results don’t apply to you at all.
Which anyone who had a) read the study or b) actually spoken to the lead researcher would’ve known. Because the quote above comes directly from his mouth — the scientists involved literally said that these results were not perfectly applicable to humans.
The saddest part is that many media stories acknowledged that these findings were from a mouse model and then continued on as if it didn’t matter.
Ultimately, the current best evidence is that intermittent fasting as a diet is fairly safe, but generally no more effective than any other option. There is no easy way out when it comes to losing weight. If it works for you, great!
But there’s no good reason to start starving yourself every few days.
Unless you’re a laboratory mouse.
*It’s important to note that the researchers did find that the studies were small and poorly-controlled across the board, meaning that you can’t really draw any definitive conclusions from the research. The best evidence may be that intermittent fasting is no better than any other diet, but the best evidence isn’t that great in this case.