A new study suggests that fasting three times a week may be a more effective weight-loss strategy than following a daily reduced-calorie diet. Participants who adopted this intermittent fasting approach lost over 50 percent more weight than those who restricted their calorie intake every day.
The research, published in the Annals of Internal Medicine, adds to the growing interest in alternative dieting strategies as obesity rates continue to climb globally. With over one billion people affected by obesity worldwide, identifying the most sustainable and effective weight-loss methods remains a pressing concern.
Why three days of fasting may be the sweet spot for weight loss
The study’s co-lead author, Dr Victoria Catenacci, an associate professor at the University of Colorado Anschutz Medical Campus, believes that fasting three times a week strikes the right balance between flexibility and effectiveness.
“More fasting days per week may be too rigid and difficult to stick to, while fewer may not create enough of a calorie deficit to outperform daily calorie restriction diets,” she explained.
How the study was conducted
Researchers examined 165 overweight or obese individuals, dividing them into two groups:
- Intermittent fasting group (4:3 method): Participants fasted three days a week, reducing their calorie intake by 80 percent on fasting days, but eating without restrictions on the remaining four days. They were encouraged to make healthy food choices, but calorie counting was not required.
- Daily calorie restriction group: Participants maintained a consistent 34.3 percent calorie deficit each day.
Both groups were given behavioral support, free gym memberships, and were encouraged to exercise for at least 300 minutes per week.
Intermittent fasters lost more weight
After one year, the results showed:
- The intermittent fasting group lost an average of 7.7 kg (7.6 percent of their body mass).
- The daily calorie restriction group lost 4.8 kg (5 percent of their body mass).
- Dropout rates were lower among intermittent fasters (20 percent) compared to calorie restrictors (30 percent).
These findings suggest that fasting three days a week may be easier to sustain than continuous calorie restriction, particularly since fasters did not have to count calories daily and had unrestricted eating days to look forward to.
Why intermittent fasting might work better
Researchers noted that intermittent fasting could lead to an unintentional reduction in overall food intake even on non-fasting days. This aligns with previous research indicating that structured fasting periods may encourage people to consume fewer calories overall—whether consciously or subconsciously.
“This may explain why the 4:3 group was closer to the calorie deficit target overall,” said Dr Adam Collins, a nutrition expert at the University of Surrey, who was not involved in the study.
Collins added that these findings reinforce the idea that intermittent fasting approaches may be more effective and sustainable than traditional calorie restriction, particularly when considering long-term adherence and real-world application.
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The search for sustainable weight loss solutions
With obesity rates soaring, the demand for weight-loss solutions has fueled interest in pharmaceutical options like Ozempic, Wegovy, and Mounjaro. However, these medications remain costly and their long-term effects are still under investigation.
As a result, non-pharmaceutical weight-loss strategies—such as intermittent fasting—continue to be explored as viable alternatives.
Different fasting methods, including the 5:2 diet (fasting two days a week) and alternate-day fasting, have gained popularity, while time-restricted eating (limiting food intake to specific hours each day) is also being studied for its potential benefits.
Also Read | Weight loss: 13 tips and tricks to lose weight without diet or exercise
This latest study adds to the growing evidence that intermittent fasting can be an effective, manageable, and sustainable approach to weight loss, potentially outperforming traditional calorie-restricted diets in both compliance and results.
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