There is no one-size-fits-all when it comes to weight-loss, and a flexible approach can be as beneficial as a structured one, according to a new study by the CSIRO.
The four-month study is, they say, “one of the largest and most comprehensive clinical studies on intermittent/alternate day fasting and meal replacements”.
One hundred and sixty-four participants were divided into two groups. The first group was placed on a “flexi” diet where they “fasted” for three days of the week ((in this case “fasting” days involved between 2500 kilojoules and 4500 kilojoules depending on the individual’s body size), were calorie-controlled for three and had one day where they could eat as they pleased. The second control group was on a calorie-controlled diet seven days a week consisting of two meal replacements and one “healthy” meal of vegetables and protein.
All of the participants were provided with recipe ideas and virtual consultations with dietitians.
At the end of the 16 weeks, participants had lost an average of 11 kilograms, which they had maintained in the eight-week follow-up. They also all experienced health benefits including improvements in cholesterol, insulin, glucose and blood pressure.
“It tells us that both diets work equally well in assisting people to lose weight and get health benefits – there are options out there, so if a certain style of dieting does or doesn’t suit someone, they can try something different,” said CSIRO Research Dietitian Dr Jane Bowen.
Intermittent fasting has surged in popularity in recent years.
Bowen believes it is because people are searching for solutions to combat the rising rates of obesity (currently about two-thirds of Australian adults are overweight or obese).
“There have been many studies to show that a huge proportion of the general population are trying to lose weight at any one time and it’s about exploring strategies that might be a little bit different but are more effective because we know that maintaining weight-loss is very challenging,” Bowen said.
Prior to recent research highlighting the benefits of fasting, it was deemed ineffective and even unsafe.
“Science does evolve and change over time and becomes increasingly sophisticated,” Bowen explained. “There have been some interesting studies to show that there are a range of health benefits from periods of fasting … We’ve seen that when following that diet people have improvements in blood pressure, they had improvements in their lipid profile and even their insulin levels went down which is a good thing in terms of diabetes risk. Fasting, as a strategy for weight-loss, does come with health benefits.”
While the CSIRO research was funded by meal replacement company Impromy, other experts say that meal replacements, intermittent fasting and calorie restriction are all potentially effective options.
“All of the scientific research to date, including a recent clinical trial of 12 months, suggests that popular intermittent fasting diets are equivalent to conventional diets in terms of weight loss and health benefits,” said Associate Professor Amanda Salis from the University of Sydney’s Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders. “This means that if intermittent fasting diets appeal to you as a means of weight loss or weight management, and if your health care provider has given you the all-clear, then they are a valid option to try.”
Salis added: “Meal replacement products are a highly effective but undervalued and under-utilised tool for weight management. It is good to see them being used in an intermittent fasting regime, because meal replacement products help people to meet their needs for essential nutrients despite consuming very few kilojoules.”
Dietitian Melanie McGrice agreed adding that most studies on intermittent fasting have been conducted using meal replacements.
“The advantage of intermittent fasting with meal replacements is that people can maintain a low intake of kilojoules, while still meeting their nutritional requirements and having the flexibility to be able to eat out with friends and family,” McGrice said.
Bowen said it’s important to provide people with different options as some thrive off the structure of constantly controlled calories while others struggle.
“The concept of eating less on some days in order to give the flexibility to eat more on another day is appealing for a lot of people,” Bowen said.
“A lot of people might try the constant energy restriction and feel like it’s just too difficult on the weekends and if they blow their diet they just give up, whereas this legitimises having a day off and acknowledges that social situations happen, parties happen and it allows people to build that into their weight management.”