- Intermittent fasting didn’t meaningfully beat standard diet advice for weight loss.
- It may lead to slightly more loss than doing nothing, but evidence is uncertain.
- Long-term results and diabetes outcomes are largely missing from the research.
If you want to lose weight, you’ve probably flipped through all kinds of researched—and not-so-well-researched—opinions on the best way to lose weight and keep it off. While calorie-restricted diets have long been the go-to strategy, they can lead to initial success but fail to deliver sustained results. Enter intermittent fasting: a dietary approach that alternates between periods of little to no caloric intake and normal eating.
Promoted widely in blogs and on social media, intermittent fasting has gained popularity for its potential to enhance fat metabolism, improve insulin sensitivity and support glucose regulation. But does it live up to the hype? A recent review sheds light on the benefits, limitation, and uncertainties surrounding intermittent fasting as a weight-loss strategy. The results were published in a Cochrane database.
How Was This Study Conducted?
To evaluate the effectiveness of intermittent fasting, researchers conducted a systematic review of 22 randomized controlled trials involving 1,995 participants. These studies spanned countries like the United States, Australia, China and Germany. The trials compared intermittent fasting methods, such as time-restricted feeding and alternate-day fasting, with regular dietary advice, no intervention and those who were on a waiting list to begin intermittent fasting.
The review focused on key outcomes, including weight loss, quality of life, participant satisfaction and more. Researchers used robust tools like the Cochrane risk of bias tool to assess study quality and synthesized results using meta-analysis where possible. The minimum intervention duration was four weeks, with follow-ups extending to at least six months, ensuring a comprehensive evaluation of short-term effects.
What Did the Study Find?
The findings revealed a mixed bag of results. When compared to regular dietary advice, intermittent fasting showed little to no difference in weight loss. Similarly, it had minimal impact on achieving a 5% reduction in body weight or improving quality of life. Adverse events were also comparable.
When compared to those on the waitlist and those not using any interventions around healthy eating, intermittent fasting likely resulted in slightly greater weight loss. However, its effects on quality of life and adverse events remained uncertain, with very low-certainty evidence due to imprecision and risk of bias.
Notably, none of the included studies reported on participant satisfaction, diabetes status or overall comorbidities, leaving significant gaps in the evidence.
Limitations
While the review provides valuable insights, it’s important to acknowledge its limitations. Most studies focused on short-term outcomes, with follow-ups capped at 12 months. This restricts the ability to draw conclusions about the long-term sustainability and health impacts of intermittent fasting. Additionally, the evidence was often rated as low or very low certainty due to methodological issues, such as small sample sizes and inconsistent reporting.
Another limitation is the lack of data on diverse populations. The included studies primarily represented high-income countries, leaving questions about how intermittent fasting might perform in low- and middle-income settings or among different demographic groups.
How Does This Apply to Real Life?
For people considering intermittent fasting, the findings suggest that it may not offer significant advantages over traditional calorie-restricted diets. For some, the structured nature of intermittent fasting may provide a helpful framework, while others may find it challenging to adhere to. This study suggests it isn’t a must-do for everyone.
It’s also worth noting that intermittent fasting is not a one-size-fits-all solution. Factors like work schedules, social commitments and medical conditions can influence its feasibility. Your best bet is to follow the advice of a health care provider to learn which strategies may be best for you.
Our Expert Take
A recent Cochrane review took a deep dive into 22 randomized controlled trials, involving nearly 2,000 participants, to see how intermittent fasting stacks up against regular dietary advice, doing nothing or simply waiting to start. The results? While intermittent fasting showed some modest weight-loss benefits compared to no intervention, it didn’t outperform traditional calorie-restricted diets in any meaningful way. Working with a registered dietitian can help you find a weight loss approach that best fits your lifestyle and goals.
