Alternate Fasting Vs. Traditional Diets: Who Wins the Weight Loss Battle?

Alternate day fasting may offer slightly greater advantages in weight reduction compared to traditional calorie restriction and other intermittent fasting approaches, as found in a comprehensive analysis published by The BMJ. Despite these differences being modest, they suggest a potential role for alternate day fasting within weight management strategies, although further long-term trials are needed to confirm its impact (1^✔ ✔Trusted Source
Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials

Go to source). Global health data reveals that around 2.5 billion adults—43% of the world’s adult population—were overweight in 2022, with about 890 million living with obesity. Weight reduction is known to improve several cardiometabolic risk factors including elevated blood pressure, cholesterol, and blood sugar, helping reduce the burden of chronic illnesses such as type 2 diabetes and cardiovascular conditions.

Understanding Intermittent Fasting Approaches

Intermittent fasting follows patterns of alternating between eating and fasting within defined periods and has emerged as a more flexible alternative to the often rigid and difficult-to-maintain calorie-restricted diets. Although it lacks a universal definition, intermittent fasting includes three primary types:

• Time restricted eating (such as fasting for 16 hours followed by 8 hours of eating),
• Alternate day fasting (fasting every other day), and
• Whole day fasting (like the 5:2 approach involving two fasting days per week).

The precise effects of intermittent fasting compared to continuous calorie restriction or unrestricted eating have remained uncertain. To clarify this, researchers assessed data from 99 randomized clinical trials involving 6,582 adults, mostly female, with an average body mass index of 31 and nearly 90% having existing health conditions.

Key Comparisons and Findings from Clinical Trials

Trial durations ranged between 3 and 52 weeks, with an average length of 12 weeks. Despite varying quality, researchers used standard tools to assess evidence strength and potential bias. Across all approaches, both intermittent fasting and calorie-restricted diets led to modest weight loss when compared to unrestricted eating habits.

Among them, alternate day fasting uniquely showed a slightly greater reduction in body weight compared to continuous calorie restriction (average difference of -1.29 kilograms). It also outperformed other intermittent fasting methods: -1.69 kilograms compared to time restricted eating and -1.05 kilograms compared to whole day fasting.

Cardiometabolic Outcomes and Limitations

However, these differences fell short of the 2-kilogram threshold considered clinically significant for people with obesity. Alternate day fasting was associated with lower total and low-density lipoprotein (commonly known as "bad") cholesterol levels when compared to time restricted eating. In contrast, time restricted eating slightly raised cholesterol levels compared to whole day fasting. No differences were seen in blood sugar or high-density lipoprotein ("good") cholesterol across any diet types.

When looking at follow-up duration, benefits were primarily noted in trials lasting less than 24 weeks. In longer trials, benefits were only observed when comparing fasting strategies to unrestricted diets, not between fasting types or calorie restriction.

Positioning Fasting as a Complement, Not a Replacement

Despite notable variability across studies, smaller sample sizes, and moderate levels of certainty, this analysis is among the first to provide detailed comparisons between multiple dietary strategies. Its strength lies in integrating direct and indirect comparisons to yield clearer insights into the relative effectiveness of these approaches.

As emphasized in a linked editorial by nutrition experts from Colombia, the findings do not aim to crown a single superior method but rather to present alternate day fasting as a viable addition to therapeutic options. They stress that benefits of dietary plans often stem from professional support, meal planning, and education, not merely the eating pattern itself. Integrating intermittent fasting into a sustainable and personalized nutrition plan can help support long-term health outcomes.

In conclusion, alternate day fasting appears to offer slightly more weight loss benefit compared to other dietary strategies, though the effects are modest and not always clinically significant. Rather than serving as a one-size-fits-all solution, intermittent fasting can be part of a broader, individualized approach to health, emphasizing sustainability and long-term lifestyle changes.

Reference:

1. Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials - (https://www.bmj.com/content/389/bmj-2024-082007)

Source-Medindia