A new Cochrane review reveals that intermittent fasting may not be more effective than standard diet strategies or even no structured program for weight loss in overweight or obese adults. This calls into question the common belief that altering when you eat yields superior weight loss results compared to conventional methods.
Obesity is a significant public health issue and ranks among the leading causes of death in affluent nations. As reported by the World Health Organization, adult obesity rates have more than tripled since 1975. In 2022, around 2.5 billion adults were categorized as overweight, with 890 million classified as living with obesity.
In contrast, intermittent fasting has surged in popularity, driven by social media trends, wellness influencers, and widespread claims of rapid weight loss and enhanced metabolism, effectively making fasting a mainstream weight loss tactic.
Review of 22 Clinical Trials Finds No Clear Benefit
To investigate the true effectiveness of intermittent fasting, researchers analyzed data from 22 randomized clinical trials involving 1,995 adults from North America, Europe, China, Australia, and South America. The studies examined various fasting methods, such as alternate-day fasting, periodic fasting, and time-restricted eating, with most participants followed for up to one year.
When compared to standard dietary advice or the absence of any intervention, intermittent fasting did not yield a significant difference in weight loss. Essentially, fasting regimens did not prove more effective than traditional guidelines or no specific plan at all.
The researchers pointed out that side effects were not consistently reported across the studies, complicating the assessment of potential risks. With only 22 trials available—many of which were small and inconsistently reported—there remains a limited overall evidence base.
“Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” said Luis Garegnani, the lead author of the review from the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre.
Social Media Hype vs Scientific Evidence
Garegnani warned that the enthusiasm seen online may outpace the evidence. “Intermittent fasting may be a reasonable option for some individuals, but the current data does not support the fervor we observe on social media,” he noted.
Another concern raised is the absence of long-term research. Few studies have assessed the effectiveness of intermittent fasting over extended periods. “Obesity is a chronic condition, and short-term trials offer limited guidance for long-term decision-making for both patients and clinicians,” Garegnani remarked.
Most trials primarily involved white participants from high-income countries. Given the rapidly rising obesity rates in low and middle-income countries, there is a pressing need for more research within these populations.
The authors also stress that the findings may not be universally applicable. Results might vary depending on factors such as sex, age, ethnicity, medical conditions, or pre-existing eating disorders and behaviors.
“With the present evidence, it’s challenging to make blanket recommendations,” stated Eva Madrid, senior author from the Cochrane Evidence Synthesis Unit Iberoamerica. “Physicians should approach weight loss advice on a case-by-case basis for overweight adults.”
In conclusion, while intermittent fasting remains a popular approach to weight loss, the scientific evidence does not strongly support its effectiveness over traditional dieting methods. As research continues, individuals seeking to lose weight should consider personalized guidance to find the most suitable strategies for their needs.
