What if there was a way to lose weight without drastic food changes or gym hours? Enter ‘intermittent fasting’: success guaranteed — just make friends with hunger!
Dieting often seems like high fashion — what’s popular today is out of style tomorrow. But there is nothing new about fasting. In fact, it’s been at the core of many religious practices across cultures for thousands of years. What is new is the weight-loss angle, which has turned intermittent fasting diets into one of the biggest health trends today.
What does fasting involve?
Intermittent fasting diets prescribe a set time of fasting followed by periods where eating is allowed. The most popular fasting diet is known as the 5:2 Diet, which severely restricts calories for two days per week and allows you to eat normally during the other five.
Alternating days of fasting followed by days of feasting are also popular. Yet another variation is a 16–hour overnight fast, where all your eating is restricted to an eight-hour window each day.
Do fasting diets work?
Fasting diets do work for weight loss, but not for everyone. Importantly, when you compare them with the more traditional diets, they don’t offer an extra advantage for those of us seeking long-term weight loss.
A recent review of nine intermittent fasting weight-loss trials, each of which ran for a minimum of six months, discovered both intermittent fasting, and just ongoing kilojoule restriction, produced the same amount of weight loss at the end of the trials.
The new ‘Flexi’ Diet
Now here comes the new kid on the fasting block: the CSIRO ‘Flexi’ Diet, which uses a combination of intermittent fasting and meal replacement shakes. A recent clinical trial of the diet showed it does work. Interestingly, however, what didn’t make as many media headlines was that an alternative comparison diet worked just as well.
On the ‘Flexi’ Diet, you need to fast intermittently for three days of the week, eat more of a kilojoule-controlled diet on another three days, and enjoy a ‘flexi day’ when you can eat freely. You also consume meal replacement shakes for some of the meals. Fasting days are not true starvation times, however. You can still eat between 2500 and 4500 kilojoules depending on body size — less than half the normal intake.
In a four-month trial, those following the ‘Flexi’ Diet lost an average of 11 kilograms. Their cholesterol, blood pressure, insulin and glucose indicators all improved. The results looked impressive, but the control group who were on a more traditional kilojoule-controlled daily diet for seven days a week — consisting of two meal replacement shakes and one healthy meal of vegetables and protein — achieved the same amount of weight loss.
Making sense of it all
Fasting diets are not for everyone. For a start, being hungry for long periods of time is not pleasant. And the focus on food deprivation is a red flag for creating a disordered relationship with food.
There’s no one best version of a fasting diet. A fasting protocol that works for one person could be another’s idea of hell. Consider trying different approaches. Go with the one you feel does not cause too much hunger discomfort — one you’re likely to stick to.
Plan ahead to keep busy on your fasting days so that your mind is off food. Crucially, try not to treat eating days as an excuse to binge: stick to eating healthily with just a small increase in the food you eat.