Intermittent Fasting: New Study Debunks Weight Loss Hype

Top Summary

• What happened: A Cochrane review of 22 studies found intermittent fasting is no more effective for weight loss than standard dietary advice or no intervention.
• Why it matters: Challenges the popular belief that intermittent fasting is a superior weight loss method.
• What changes for people: Individuals may need to reconsider intermittent fasting as a primary weight loss strategy.
• Who is affected: Overweight and obese adults seeking effective weight loss methods.

The Verdict on Intermittent Fasting

Intermittent fasting has gained popularity as a weight loss strategy. However, a new review from the Cochrane Collaboration suggests it's not more effective than traditional methods.

The international review assessed 22 studies with 1,995 overweight or obese adults. Researchers compared intermittent fasting to dietary advice and no intervention over 12 months.

Comparing Weight Loss Strategies

Intermittent fasting includes strategies like alternate day fasting, the 5:2 diet, and time-restricted eating (16:8).

Previous research showed alternate day fasting resulted in more weight loss than time-restricted eating. This is because participants consumed about 20% less energy with alternate day fasting.

Cochrane Review Key Findings

The Cochrane review analyzed randomized controlled trials from 2016 to 2024 across North America, Europe, China, Australia, and South America.

The review compared outcomes of nearly 2,000 participants receiving dietary advice, practicing intermittent fasting, or receiving no intervention.

Fasting vs. Dietary Advice

Researchers found that intermittent fasting and dietary advice led to similar weight loss. This was based on 21 studies with 1,713 people.

Dietary advice included plans focused on fruits, vegetables, whole grains, and seafood, or calorie restriction.

Weight loss ranged from a 10% loss to a 1% gain in both groups. This aligns with recent meta-analyses that found intermittent fasting is no better than dieting.

Previous research shows alternate day fasting and periodic diets lead to about 6% to 7% weight loss. This compares to very low energy "shake" diets (about 10%), GLP-1 medications (15% to 20%), and surgery (above 20%).

The review also found intermittent fasting likely makes little difference to a person's quality of life, based on only three studies.

Fasting vs. No Intervention

Intermittent fasting and no intervention led to similar levels of weight loss, based on six studies involving 448 people.

Participants in the intermittent fasting groups experienced about 5% weight loss. The "no intervention" group lost about 2% of their original weight.

A 3% difference in weight loss is not considered clinically meaningful. The "no intervention" result could be due to the Hawthorne effect.

Limitations of the Review

The review noted the limited number of large, high-quality randomized controlled trials.

Only six studies compared intermittent fasting and doing nothing. Two focused on time-restricted eating, and the interventions lasted between six and 12 months.

It's possible intermittent fasting strategies could be a long-term tool for weight maintenance, but more research is needed.

Potential Health Benefits

Studies have found intermittent fasting can lower blood pressure, improve fertility, and reduce the incidence of metabolic syndrome.

A 2024 study found intermittent fasting may restrict cancer development. A 2025 study found it could improve metabolic health of shift workers.

 

"For any weight loss strategy to work, it needs to align with your personal preferences. And it's best to consult a health-care professional before starting any new diet, especially if you have any underlying health conditions."

 

What to Watch Next

Future research should focus on longer-term studies to assess the effectiveness of intermittent fasting for weight maintenance. Further investigation into the specific health benefits of different intermittent fasting methods is also warranted.