Intermittent Fasting: Modest weight Loss & Cardiometabolic Effects, New Study Finds
BOSTON – june 30, 2025 – New research published today in The BMJ indicates that intermittent fasting (IF) strategies lead to small reductions in body weight when compared to unrestricted dieting, but the benefits vary depending on the specific IF method. The comprehensive analysis, conducted by researchers at Harvard T.H. Chan School of Public Health, reviewed data from 99 randomized clinical trials encompassing over 6,500 adults [[2]], [[3]].
Key Findings:
Weight Loss: All intermittent fasting and continuous energy restriction diets resulted in weight loss compared to ad libitum (unrestricted) diets.
Alternate-Day Fasting Stands Out: Alternate-day fasting was the only IF strategy demonstrating a statistically significant benefit in weight reduction compared to continuous energy restriction, with an average difference of -1.29 kg.
Long-Term Benefits: Weight reduction benefits were more pronounced in trials lasting 24 weeks or longer. Shorter trials showed similar estimates, but the advantage of IF over continuous restriction diminished.
Cardiometabolic Impacts: Alternate-day fasting showed improvements in total cholesterol, triglycerides, and non-high-density lipoprotein levels compared to other IF methods.Conversely, time-restricted eating was associated with a slight increase in total cholesterol, LDL cholesterol, and non-high-density lipoprotein cholesterol when compared to whole-day fasting.What is Intermittent Fasting?
Intermittent fasting involves cycling between periods of eating and voluntary fasting on a regular schedule [[3]]. Common methods include:
Alternate-Day Fasting: Alternating between days of eating normally and days of very limited calorie intake.
Time-Restricted eating: Consuming all meals within a specific window of time each day (e.g., 16/8 method – fasting for 16 hours, eating within an 8-hour window).
* Whole-Day Fasting: Fasting for one or two non-consecutive days per week.
Expert commentary:
“our analysis suggests that while intermittent fasting can be a tool for weight management, it’s not a magic bullet,” said Dr. Zhila Semnani-Azad, lead author of the study.”the type of intermittent fasting employed and the duration of the diet appear to be crucial factors in determining its effectiveness.”
Implications & Considerations:
This research underscores the importance of personalized dietary approaches. While IF may offer benefits for some,it’s essential to consider individual health status and preferences. The study also highlights the need for longer-term research to fully understand the sustained effects of diffrent IF strategies on cardiometabolic health.
Further research is ongoing to determine the optimal IF protocols and identify individuals who are most likely to benefit.
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