Intermittent Fasting – What the latest research says?

Plate with food and empty plate on pink and yellow background, intermittent fasting concept.

The fitness industry has always been known to start some new trends. This may include some crazy diets, a bunch of supplements, or even some insane sounding therapies. One such trend is the Intermittent Fasting diet (IF). IF has been known and well-practiced in various religions as a part of their cultural belief and Ayurveda has often promoted IF for it’s health benefits along with the cultural aspect.

In this article, we are reviewing the results of a couple of latest studies on this topic.

Patterson et. all. explained periods of voluntary abstinence from food and drink as Intermittent fasting. Their review research paper was focused on the evidence on the health benefits of intermittent fasting on the human population.

There are quite a number of variations of this diet, the table below will help you understand them.

Types of intermittent fasting regimens that are hypothesized to impact health outcomes

Ref: Patterson et. all 2015

Complete Alternate Day Fasting

These regimens involve alternating fasting days (no energy-containing foods or beverages consumed) with eating days (foods and beverages consumed ad-libitum).

Modified Fasting Regimens

Modified regimens allow for the consumption of 20–25% of energy needs on scheduled fasting days. This regimen is the basis for the popular 5:2 diet, which involves severe energy restriction for 2 non-consecutive days a week and ad libitum eating the other 5 days.

Time-Restricted Feeding

These protocols allow individuals to consume ad libitum energy intake within specific windows, which induces fasting periods on a routine basis. Studies of <3 meals per day are indirect examinations of a prolonged daily or nightly fasting periods.

Religious Fasting

A wide variety of fasting regimens are undertaken for religious or spiritual purposes.

Ramadan Fasting

A fast from dawn to sunset during the holy months of Ramadan. The most common dietary practice is to consume one large meal after sunset and one lighter meal before dawn. Therefore the feast and fast periods of Ramadan are approximately 12 hours in length.

Other Religious Fasts

Latter Day Saints followers routinely abstain from food and drink for extended periods of time. Some Seventh-day Adventists consume their last of 2 daily meals in the afternoon, resulting in an extended nighttime fasting interval that may be biologically important.

In their study, they have acknowledged the lack of large trials on the human population to see the efficacy of the IF on long term weight management. Data are lacking regarding the impacts of intermittent fasting on other health behaviors such as diet, sleep, and physical activity.

One of the recent large randomized clinical trials(RCT) on IF 16:8 version conducted by Low et. al. (2020) wanted to explore the efficacy of the effect of time-restricted eating on weight loss and metabolic health in patients with overweight and obesity. This 12- week RCT included 116 adults both males and females who were then divided into two groups, one to follow IF and the other to follow a consistent eating plan. The participants in the IF groups were allowed to eat between 12 pm – 8 am and Nil oraly thereafter versus the other group who were given instructions to eat three main meals a day.

The primary outcome studied was weight loss and a significant decrease in the baseline weight of the IF group was seen, – 1.17% and for the other group, it was -0.75%. Some other interesting findings of this study are:

  • There was no significant difference in weight change between groups, -0.26%
  • There were no statistically significant changes in estimated energy intake or energy expenditure between groups
  • No significant change was seen in the whole body fat percentage 
  • There was no significant difference in resting metabolic rate(RMR)
  • On the contrary increased loss of lean muscle mass was noted in the IF group and Appendicular lean mass (ALM) decreased significantly in the IF group, but not in the other.
  • Respiratory quotient (RQ) did not change significantly in the IF group but increased in the other group
  • There were no significant within-group or between-group differences in fasting glucose, fasting insulin, HOMA-IR, HbA1C, triglycerides, total cholesterol, LDL, or HDL levels

This study also supported the recommendation that skipping breakfast does not affect weight outcomes in patients trying to lose weight and it finally concluded that “Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day.”

My conclusion:

  • Breakfast is an important meal of the day so please do not skip it!
  • Good health is more than just weight loss.
  • In order to achieve long-term results, we need to create a balance between our diet and nutrition, physical activity, sleep, and a positive mindset.
  • If asked me to chose which is your favorite version of IF, my answer would be 5:2.

Hope this information helps you to decide to follow the right path of a healthy way of living. 

References 

  • Patterson, R. E., Laughlin, G. A., LaCroix, A. Z., Hartman, S. J., Natarajan, L., Senger, C. M., Martínez, M. E., Villaseñor, A., Sears, D. D., Marinac, C. R., & Gallo, L. C. (2015). Intermittent Fasting and Human Metabolic Health. Journal of the Academy of Nutrition and Dietetics115(8), 1203–1212. https://doi.org/10.1016/j.jand.2015.02.018
  • Lowe DA, Wu N, Rohdin-Bibby L, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med. Published online September 28, 2020. doi:10.1001/jamainternmed.2020.4153
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Purva Gulyani

Purva Gulyani – an Accredited Practising Dietitian and lifelong member of the Indian Dietitian Association. Currently pursuing PhD at Latrobe University. Purva brings over 16+ years of clinical dietitian experience to the table.

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