Researchers found no differences in weight loss between alternate-day fasting, modified alternate-day fasting, intermittent fasting, and calorie-restricted diets. The researchers found that all the diets had similar weight loss, but if you had to choose a winner, it would be ADF/MADF.
THE TOP 3 BEST FASTING DIETS FOR WEIGHT LOSS BY SCIENCE SUMMARY
Researchers found no differences in fasting diets for weight loss between alternate-day fasting, modified alternate-day fasting, intermittent fasting, and calorie-restricted diets.
The researchers found that all the diets had similar weight loss, but if you had to choose a winner, it would be ADF/MADF.
AN INTRODUCTION TO FASTING FOR WEIGHT LOSS
Diet superiority for losing body weight and fat can result in fierce debates online and at scientific conferences. As discussed in a previous article on Evidence Based Muscle, we can end the debate on a low-carb vs. low-fat diet. Numerous studies have shown that when protein intake is similar between high and low-carb diets, weight loss and fat loss are the same.
In a year-long study comparing low-carb vs low-fat diets in, which involved 600+ participants, researchers found no differences in body weight. The low-fat group had lost 11.7 lbs. (5.3 kg), and the low-carb group had 13.2 lbs. (6.0 kg) weight loss. (Gardner et al., 2018)
IS THERE A BEST INTERMITTENT FASTING SCHEDULE?
Over the past few years, intermittent fasting (IF) has increased in popularity for weight loss. (He et al., 2021) There are many different types of fasting protocols:
- ALTERNATE DAY FASTING (AF): Eat one day as much as you want and fast the next day.
- MODIFIED ALTERNATE DAY FASTING (MADF): Calories are restricted by 20-30% of your normal intake on fasting days.
- 5:2 FASTING PROTOCOL: Eating normally 5 days a week and stopping eating or reducing calorie intake on two consecutive or nonconsecutive days.
There is also time-restricted eating (TRE) in which you eat within a certain time frame. Most TRE diets require individuals fast for 14 to 16 hours per day and eating windows for 4 to 12 hours. (Pureza et al., 2021) The most popular TRE diets are:
- 16/8 IF: 16 hours of fasting, eat within an 8-hour window.
- 14/10 IF: 14-hour fasting period; eat within a 10-hour window.
- Other windows are 15: 9 intermittent fasting and intermittent fasting 18/6.
There have been discussions about whether you will lose muscle mass or have a slower metabolism following a fasting diet. To date, IF has not been shown to reduce protein synthesis, decrease muscle mass, or result in metabolic decline compared to a standard energy-restricted diet.
THE TOP 3 BEST FASTING DIETS FOR WEIGHT LOSS BY SCIENCE
Traditional recommendations for weight-loss diets are consuming 500 calories less each day. (Kim, 2021) Weekly weight loss recommendations are 1 pound per week; fast weight loss is associated with greater losses of lean muscle mass. (McCarthy & Berg, 2021)
AF and IF protocols have been deemed “alternative” weight-loss methods to the typical calorie-restricted diet that may have additional benefits for metabolic health (i.e., lower blood sugar) and longevity. (Patterson & Sears, 2017) The health benefits of AF are limited by long-term adherence. Studies have shown that diet adherence declines 1 to 4 months after diet initiation. (Rynders et al., 2019; Varady et al., 2021) Side effects of AF/IF are drops in blood sugar and fatigue.
Researchers examined the various alternate-day and intermittent fasting studies and which one was the best. A total of 24 studies involving 1,768 participants were included in the literature review.
The researchers compared: (i) ADF/modified ADF (12 studies), (ii) the 5:2 diet (8 studies), (iii) TRE (4 studies), (iv) calorie restriction (15 studies), and (v) ad libitum eating (i.e., no dietary restriction; 9 studies). The study durations ranged from 3 to 26 weeks. The researchers also examined weight loss and dietary adherence to different fasting protocols.
WHICH IS THE BEST INTERMITTENT FASTING WINDOW TO LOSE BELLY FAT?
At the end of the study, all the diets were equally effective for weight loss! Here is a breakdown of the numbers of each fasting protocol:
ADF/MADF VS. 5:2 VS. TRE
ADF/MADF weight loss was .77% – 12.97%
5:2 fasting weight loss was 1.70% – 8.60%.
TRE weight loss was .95% to 8.60%
The results were not statistically significant despite the ADF/MADF having greater weight loss.
IF VS. CALORIE RESTRICTED DIETS
There was no difference in weight loss between calorie-restricted diets and IF. The order of the greatest weight loss to least by diet was:
1.) ADF/modified ADF ranked the highest as most effective for weight loss
2.) Calorie restriction
COMPLIANCE BETWEEN DIETS
One of the biggest misconceptions about fasting diets is that people can’t stick to fasting diets; however, research has found that compliance is high with fasting diets. All the diets resulted in similar compliance. The compliance among all the studies was: TRE ranked the highest (94%), 5:2 (88%), and ADF/MADF (85%).
All the diets resulted in similar weight loss, but if you had to choose a winner, it would be ADF/MADF. These results are similar to the recent studies showing similar weight loss with IF and calorie restriction. (Enríquez Guerrero et al., 2021; Harris et al., 2018) The author concluded, “Taken together, our results suggest that IF may be implemented as an alternative strategy to calorie-restricted diets for weight loss and weight management tailored to the specific needs and acceptance by the individual.”
Enríquez Guerrero, A., San Mauro Martín, I., Garicano Vilar, E., & Camina Martín, M. A. (2021). Effectiveness of an intermittent fasting diet versus continuous energy restriction on anthropometric measurements, body composition and lipid profile in overweight and obese adults: a meta-analysis. Eur J Clin Nutr, 75(7), 1024-1039. https://doi.org/10.1038/s41430-020-00821-1
Gardner, C. D., Trepanowski, J. F., Del Gobbo, L. C., Hauser, M. E., Rigdon, J., Ioannidis, J. P. A., Desai, M., & King, A. C. (2018). Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA, 319(7), 667-679. https://doi.org/10.1001/jama.2018.0245
Harris, L., Hamilton, S., Azevedo, L. B., Olajide, J., De Brún, C., Waller, G., Whittaker, V., Sharp, T., Lean, M., Hankey, C., & Ells, L. (2018). Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database System Rev Implement Rep, 16(2), 507-547. https://doi.org/10.11124/jbisrir-2016-003248
He, S., Wang, J., Zhang, J., & Xu, J. (2021). Intermittent Versus Continuous Energy Restriction for Weight Loss and Metabolic Improvement: A Meta-Analysis and Systematic Review. Obesity (Silver Spring), 29(1), 108-115. https://doi.org/10.1002/oby.23023
Kim, J. Y. (2021). Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance. Journal of obesity & metabolic syndrome, 30(1), 20-31. https://doi.org/10.7570/jomes20065
McCarthy, D., & Berg, A. (2021). Weight Loss Strategies and the Risk of Skeletal Muscle Mass Loss. Nutrients, 13(7), 2473. https://doi.org/10.3390/nu13072473
Patterson, R. E., & Sears, D. D. (2017). Metabolic Effects of Intermittent Fasting. Annu Rev Nutr, 37, 371-393. https://doi.org/10.1146/annurev-nutr-071816-064634
Pureza, I., Macena, M. L., da Silva Junior, A. E., Praxedes, D. R. S., Vasconcelos, L. G. L., & Bueno, N. B. (2021). Effect of early time-restricted feeding on the metabolic profile of adults with excess weight: A systematic review with meta-analysis. Clin Nutr, 40(4), 1788-1799. https://doi.org/10.1016/j.clnu.2020.10.031
Rynders, C. A., Thomas, E. A., Zaman, A., Pan, Z., Catenacci, V. A., & Melanson, E. L. (2019). Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss. Nutrients, 11(10). https://doi.org/10.3390/nu11102442
Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic Benefits of Intermittent Fasting. Annu Rev Nutr, 41, 333-361. https://doi.org/10.1146/annurev-nutr-052020-041327