Intermittent fasting (IF) is gaining popularity as an alternative strategy for weight loss and management, but how effective is it compared to a traditional caloric restriction diet?

Interested to learn about the essentials of IF? Read our introductory article here

The effectiveness of intermittent fasting

A recent study compared the effectiveness of different IF regimens – alternate day fasting, the 5:2 diet, and time-restricted fasting, to the traditional calorie restriction (CR) diet in the general population for weight loss (1). The study also investigated the compliance of IF and CR.

The study conducted was a meta-analysis, which is considered the highest quality medical evidence. The researchers investigated randomised controlled clinical trials, including a total of 24 studies and 1768 participants, published between 2011- 2021, and used statistical methods to summarize the findings and make conclusions.

The study found that all three primary types of intermittent fasting (IF) – alternate day fasting, the 5:2 diet, and time-restricted eating – were effective in reducing body weight and body fat when compared to control groups (1). These IF protocols resulted in body weight reductions that varied from 1% to 13% over durations ranging from 2 to 52 weeks (1). No significant differences were found between the IF regimens in terms of weight loss, implying that they might be equally effective in reducing body weight.

In comparison to CR, IF did not show any significant differences in terms of weight-loss effectiveness (1).

Compliance, which is a critical factor in the success of weight-loss interventions, was found to be moderately high for all three IF protocols and CR at the beginning (80%) but declined over time (1). The adherence to each protocol was similar, indicating that the different types of IF and CR had comparable compliance rates.

The researchers noted that all three methods were associated with high dropout rates and adherence difficulties, suggesting that sustained compliance may be a challenge for some individuals (1). Overall, the study concluded that all three methods of IF are effective for weight loss, but further research is needed to identify the optimal protocol for different populations and to determine their long-term effects on weight management and metabolic health.

The findings indicate that IF could be used as an alternative approach to CR for weight loss and weight management that can be tailored to the specific needs and acceptance by the individual (1).

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Read more about intermittent fasting:

Introduction to intermittent fasting
Health benefits of intermittent fasting beyond weight loss

Silviya Demerzhan, Ph.D.

Chief Scientific Officer, Nordic Executive Medicine
Medical review by: Dr. Mahir Vazda MD

References

  1. Elortegui Pascual P, Rolands MR, Eldridge AL, Kassis A, Mainardi F, Lê KA, et al. A meta-analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time-restricted eating for weight loss. Obesity. 2023;31(S1):9–21.