Intermittent fasting for adults with overweight or obesity.

Area of Science:

• Nutrition and Dietetics
• Metabolic Health
• Obesity Research

Background:

• Weight loss is crucial for managing overweight and obesity-related health risks.
• Calorie-restricted diets are common but often yield unsustained weight loss.
• Intermittent fasting (IF) shows potential mechanisms for weight loss, but evidence is inconsistent.

Purpose of the Study:

• To evaluate the benefits and harms of intermittent fasting (IF) versus regular dietary advice or no intervention in adults with overweight or obesity.
• To assess IF's impact on weight loss, quality of life, and adverse events.

Main Methods:

• Systematic review and meta-analysis of randomized controlled trials (RCTs) and cluster-RCTs.
• Searched multiple databases up to November 2024, including CENTRAL and MEDLINE.
• Included 22 studies with 1995 participants, comparing IF with dietary advice or no intervention for at least 4 weeks, with follow-up of at least 6 months.

Main Results:

• Compared to regular dietary advice, IF showed little to no difference in percentage weight loss (low-certainty evidence) and quality of life (low-certainty evidence).
• Compared to no intervention, IF likely resulted in little to no difference in percentage weight loss (moderate-certainty evidence) and quality of life (very low-certainty evidence).
• Evidence for IF's effect on adverse events was very uncertain in both comparisons.

Conclusions:

• Intermittent fasting (IF) demonstrated little to no significant difference in weight loss or quality of life compared to regular dietary advice or no intervention in short-term studies (up to 12 months).
• The evidence regarding adverse events is highly uncertain, necessitating cautious interpretation.
• Further long-term studies are required, focusing on participant satisfaction, diabetes status, comorbidities, and diverse populations.