Jacqueline Whitehart, author of the 5:2 Fast Diet Recipe Book, knows this of course, which is why her new diet book was released this week, just in time for a ‘new year, new you’.
Claiming that her previous diet had become too “difficult” to fit into her lifestyle anymore, Whitehart told Daily Mail she’d developed a new diet over two years that participants would lose weight following without the days of fasting.
It's called the Metabolic Fat Loss Diet Plan and it involves four alternating phases over 28 days: Detox and De-stress, Protein and Healthy Fats, Better Carbs and Balanced Eating.
After an initial four days of eating reduced-calorie meals with a ratio of 50 per cent energy from carbohydrates, 30 per cent from protein and 20 per cent from fats, followers will alternate between the Protein and Healthy Fats and Better Carbs phases for three days at a time.
The Protein and Healthy Fats phase balance is: Carbs: 20/Protein: 40/Fats: 40 which doesn't allow for much fruit or dairy. Whereas the Better Carbs phase allows for fruit and even dark chocolate with a ratio of Carbs: 40/Protein: 40/Fats: 20. Finally, participants end with a more relaxed Balanced Eating phase to set them up to follow healthy eating patterns once the diet ends.
Whitehart claims that her diet is more "realistic and doable" than the 5:2 Diet and that alternating the four phases "shocks your metabolism into burning fat more efficiently".
So will it actually work?
LISTEN: Brigid Delaney explains the Bondi Wellness paradox to Mia Freedman. (Post continues after audio.)
To find out we spoke to accredited practising dietitian and Nourishing Bubs founder Olivia Bates, who said there was some merit to the diet, but it still contained areas of concern.
"In terms of diets, there are some shockers out there and I really don't think this one's it, but I guess the major thing with anything like this is the ability to maintain it afterwards," the nutritionist said.
"Following these methods yes, you can definitely see results, but is it a long-term result?"
Bates said that any diet, such as this one, which included reducing calories would result in weight-loss, but no research she had ever come across professionally suggested changing up your eating habits every few days would improve your metabolism.
"There's no scientific research that I've seen that says you need to chop and change what you're eating to shock your body. It's definitely not something that's well known or I've ever read anything about."
Furthermore, Bates said the ratios in the Protein and Healthy Fats phase were concerning, with 20 per cent carbohydrates well-below the recommended amount.
The dietician said the recommended ranges are that carbohydrates should be between 45 and 65 per cent of energy, protein between 15 and 25 per cent, and fat is 20 to 35 per cent.
"Whereas a percentage of 40 percent is really high and the major issue of this is it puts a heavy load onto kidneys, so you wouldn't want to be doing that for a long time."
Bates explained our brains need glucose to function and carbs are the best source of this, so followers would likely feel tired on these low-carb days. However, she says because the stints are so short, participants would be unlikely to see any harmful long-term effects.
"The good thing about this diet is it moves on to Better Carbs and then Balanced Eating... These [stages] definitely promote some good eating habits, in terms of picking the right types of carbohydrates, having three balanced meals, avoiding things like caffeine, alcohol, etc."
Overall, Bates said while she'd prefer the diet without phase two, she thought it would result in weight-loss, but not necessarily any more than if you followed a simple, veggie and lean protein-focussed meal plan.
That's certainly food for thought.
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