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When to stop intermittent fasting: what you need to know

Written on February 6, 2023 by Sendra Yang, PharmD, MBA. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

What is intermittent fasting?

People worldwide practice fasting for religious purposes, lifestyle, or to lose weight. Intermittent fasting is a pattern of eating that alternates between periods of eating and fasting. Intermittent fasting practiced with a dieting plan can help you reach your weight loss goals [1]. The most popular intermittent fasting schedule is the 16/8 method. With this intermittent fasting schedule, you fast for 16 hours and eat within an 8-hour window. Another alternative intermittent fasting schedule is the 5:2 method, which is when you eat normally for five days, followed by two days of calorie restrictions. Most fasting practices allow drinking water, tea, coffee, or non-caloric beverages during periods of fasting.

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Why do people practice fasting?

Intermittent fasting, when practiced safely, can lead to weight loss, improved insulin sensitivity, reduced inflammation, improved brain function, improved blood sugar levels, and lower cholesterol levels [1-4]. The science of intermittent fasting and how it affects your health is the subject of ongoing research.

Reasons to stop intermittent fasting

Experiencing health risks or side effects

Despite the positive health benefits of intermittent fasting, you should also carefully weigh the health risks to determine when you should stop fasting.

After fasting for 8-12 hours, your body begins to break down fats to produce ketones, which serve as an alternative energy source for your body when it is restricted from glucose [1,5]. Long periods of unhealthy fasting can lead to side effects such as weakness, extreme hunger, dehydration, headaches, difficulty concentrating, fainting, or excessive weight loss. Other health-related risks include:

  1. Dehydration: If you are not drinking sufficient fluids during fasting, your body can become dehydrated. Symptoms of dehydration can include headaches, cramps, rapid breathing, and fatigue [6]. Dehydration can lead to serious health risks.
  2. Extreme hunger: Extreme hunger can lead to irritability, difficulty concentrating, and malnourishment.
  3. Excessive weight loss: Rapid weight loss can create an extreme physical demand on your body, leading to the severe health risk of malnutrition, dehydration, loss of muscle mass, or gallstones [7]. You should consult your healthcare provider if you are experiencing rapid and excessive weight loss.
  4. Blood pressure: Fasting can lower your blood pressure [8]. Low blood pressure can be a health concern leading to confusion, nausea, or difficulty concentrating [9].

No longer working for you

If intermittent fasting has helped you achieve your weight goals but is no longer working for you, it is probably time to consider stopping. Here are some additional reasons:

  1. Fasting is impacting your emotions. In some people, fasting can escalate negative emotions such as depression, anxiety, anger, irritability, fatigue, and tension, while diminishing positive emotions [10]. More research is needed to further investigate the effects of fasting on emotions.
  2. Hunger is a reported side effect of intermittent fasting [1,11]. A study found that 15% of participants reported hunger during intermittent energy restriction or fasting [11]. If fasting is causing you to feel hungrier than normal and interrupts your focus and work, you should consider stopping and speaking with your provider.
  3. Your weight gain has reached a plateau, and you no longer feel like you’re progressing [12]. It will help if you consult your healthcare provider to discuss why you’re no longer losing weight and maybe alternative routes to achieving your weight goals.
  4. You are no longer interested in fasting to achieve your weight loss goals. Being interested and focused can help you follow through on setting achievable weight loss goals [13]. However, if you start to lose interest, it’s no longer a good use of your time and resources. Now would be a good time to talk to your healthcare provider to consider alternative ways to shave off the weight.
  5. Low energy is making it hard to make it through your workday [14]. If fasting negatively affects your energy level, consider an alternative weight loss program. Lack of energy can lead to a lack of motivation to stick to a weight loss program to shed the weight effectively.

Final thoughts on stopping intermittent fasting

Intermittent fasting can be an effective way to achieve your targeted weight loss goals. But while intermittent fasting can lead to weight loss and improved health, it may not be for everyone.

It is essential to weigh the health risks of fasting. Extreme hunger, excessive weight loss, dehydration, low blood pressure, and weakness can be adverse health effects of fasting. If fasting is impacting your emotions, decreasing your energy levels, or causing extreme hunger, it may be time to stop.

Consult your healthcare provider if you are thinking about stopping intermittent fasting and/or looking for alternative options to achieve your weight loss goals. You can also schedule an virtual weight loss consultation with a certified healthcare provider accessed through Everlywell.

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What factors influence weight loss?

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How much is enough when looking to lose weight?

References

  1. Welton S, Minty R, O’Driscoll T, et al. Intermittent fasting and weight loss: systematic review. Can Fam Physician. 2020;66(2):117-125. URL.
  2. Zhu S, Surampudi P, Rosharavan B, Chondronikola M. Intermittent fasting as a nutrition approach against obesity and metabolic disease. Curr Opin Clin Nutr Metab Care. 2020;23(6):387-394. doi:10.1097/MCO.0000000000000694. URL.
  3. Martin B, Mattson MP, Maudsley S. Caloric restriction and intermittent fasting: two potential diets for successful brain aging. Ageing Res Rev. 2006;5(3):332-353. doi:10.1016/j.arr.2006.04.002. URL.
  4. Moro T, Tinsley G, Bianco A, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. J Transl Med. 2016;14(1). doi:10.1186/s12967-016-1044-0. URL.
  5. Dhillon KK, Gupta S. Biochemistry, Ketogenesis. [Updated 2022 Feb 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. URL.
  6. Shaheen NA, Alqahtani AA, Assiri H, Alkhodair R, Hussein MA. Public knowledge of dehydration and fluid intake practices: variation by participants’ characteristics. BMC Public Health. 2018;18(1):1346. doi:10.1186/s12889-018-6252-5. URL.
  7. Pi-Sunyer FX. Short-term medical benefits and adverse effects of weight loss. Ann Intern Med. 1993;119(7 Pt 2):722-726. doi:10.7326/0003-4819-119-7_part_2-199310011-00019. URL.
  8. Goldhamer A, Lisle D, Parpia B, Anderson SV, Campbell TC. Medically supervised water-only fasting in the treatment of hypertension. J Manipulative Physiol Ther. 2001;24(5):335-339. doi:10.1067/mmt.2001.115263. URL.
  9. Sharma S, Hashmi MF, Bhattacharya PT. Hypotension. [Updated 2022 Sep 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. URL.
  10. Wang Y, Wu R. The effect of fasting on human metabolism and psychological health. dis markers. 2022;2022:5653739. doi:10.1155/2022/5653739. URL.
  11. Harvie MN, Pegington M, Mattson MP, et al. The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomized trial in young overweight women. Int J Obes (Lond). 2011;35(5):714-27. doi:10.1038/ijo.2010.171. URL.
  12. Weight loss stalled? move past the plateau. Mayo Clinic. URL. Published April 14, 2022. Accessed February 1, 2023.
  13. Conlon KE, Ehrlinger J, Eibach RP, et al. Eyes on the prize: The longitudinal benefits of goal focus on progress toward a weight loss goal. J Exp Soc Psychol. 2011;47(4):853-855. doi:10.1016/j.jesp.2011.02.005. URL.
  14. Redman LM, Heilbronn LK, Martin CK, et al. Metabolic and behavioral compensations in response to caloric restriction: implications for the maintenance of weight loss. PLoS One. 2009;4(2):e4377. doi:10.1371/journal.pone.0004377. URL.
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