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Intermittent Fasting - What you need to know!

Intermittent fasting is, periods of voluntary abstinence from food and drink (hey, water is ok).

Various methods but the three main are:

  1. Alternate-Day fasting

  2. 5:2

  3. Time-restricted feeding

Alternate-Day Fasting - involves alternating fasting days, during which no calories are consumed, and feeding days, during which foods and beverages are consumed ad libitum.

Some studies showed weight loss, but one study that included overweight and obese participants reported a detrimental effect on postprandial glucose and insulin the day after fasting. Hunger and state of mind, as well as performance, both physical and mental, are factors to consider especially on the day of the total fast.

Overall, literature suggests that alternate-day fasting do not improve health beyond calorie restriction

Modified Fasting Regimens- generally specify that energy consumption is limited to 20–25% of energy needs on regularly scheduled fasting days.

Fasting here is describing periods of severely limited energy intake rather than no energy intake. Also called intermittent energy restriction, is the basis for the popular 5:2 diet. This diet involves energy restriction for 2 nonconsecutive days per week and unrestricted eating during the other 5 days of the week

There are no benefits beyond a classic daily energy deficit diet

A classic diet by a nutritionist is based on a relatively small daily energy deficit that becomes a way of life and can be easily adopted without deprivation. Sweets and fast food are also allowed, just everything in moderation and balance.

Time-Restricted Feeding - typically 16 h fasting and 8 h eating

Other example: overnight fasting 11 and more hours or overnight fast that continues in the morning

Let’s take a look at the long-term metabolic benefits associated with eating or not eating breakfast, that is, extending the nighttime fast until the lunch meal equivalent about to a ≥13-hour nighttime fast. Studies in obese individuals found that on the day that they did not eat breakfast, participants had higher levels of acetylated ghrelin and their post-lunch postprandial glucose and insulin levels were higher. in their 6-week controlled trial, they observed no benefit with respect to weight change, glycemic control, lipids, or inflammatory markers for the group omitting the breakfast meal compared with the control group.


Concluding, intermittent fasting has shown positive effects on weight loss, in addition to reducing insulin resistance and favorably shifting the levels of some hormones such us leptin and adiponectin. Literature supports that intermittent fasting has a wide range of benefits relatively to obesity, Type 2 diabetes and hypertension, and in improving cardiovascular risk factors but most of the studies are from animal data and many clinical trials have failed to show as significant improvements of intermittent fasting over caloric restriction.

  • The degree of weight loss achieved with intermittent fasting is equivalent to that of traditional dieting approaches (daily calorie restriction).

  • The ability of these intermittent fasting protocols to help to manage weight long-term is still poorly understood.

  • Intermittent Fasting may benefit cardiovascular health by improving obesity, hypertension, dyslipidemia and diabetes. Potential mechanisms of this diet involve reducing oxidative stress, syncing with the circadian system and inducing ketogenesis.


  • Patterson, R. E., & Sears, D. D. (2017). Metabolic Effects of Intermittent Fasting. Annual review of nutrition, 37, 371–393.

  • Vasim, I., Majeed, C. N., & DeBoer, M. D. (2022). Intermittent Fasting and Metabolic Health. Nutrients, 14(3), 631.

  • Dong, T. A., Sandesara, P. B., Dhindsa, D. S., Mehta, A., Arneson, L. C., Dollar, A. L., Taub, P. R., & Sperling, L. S. (2020). Intermittent Fasting: A Heart Healthy Dietary Pattern?. The American journal of medicine, 133(8), 901–907.

  • Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic Benefits of Intermittent Fasting. Annual review of nutrition, 41, 333–361.

  • Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2022). Clinical application of intermittent fasting for weight loss: progress and future directions. Nature reviews. Endocrinology, 18(5), 309–321.

  • Malinowski, B., Zalewska, K., Węsierska, A., Sokołowska, M. M., Socha, M., Liczner, G., Pawlak-Osińska, K., & Wiciński, M. (2019). Intermittent Fasting in Cardiovascular Disorders-An Overview. Nutrients, 11(3), 673.

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