To fast or to break-fast?



Intermittent fasting (IF) or time-restricted eating (TRE) have been popular health trends.


What is intermittent fasting?


Intermittent fasting includes alternating periods of eating and fasting. People may choose different patterns of IF or TRE to follow, including a daily feeding window (e.g. 16/8 and 14/10) or alternate day fasts.


What does the most up-to-date, good quality evidence say?


There has been some evidence to show that IF or TRE can aid in weight loss and improved metabolic health markers (glucose levels, insulin resistance, blood lipids, blood pressure).


BUT, research has shown a similar effect of IF or TRE to calorie restriction without fasting on weight loss and metabolic health markers.


Most importantly, a consistent pattern of eating that fits into your lifestyle is key for health, longevity and prevention of weight-cycling. In addition, quality of food is key for sufficient nutrition, energy and satiety.

When should we eat?


Whenever you decide to start your eating window, consider the following:

  • Try to eat when you feel like your stomach is slightly empty and you could eat (generally 2-4 hours after a meal/snack), rather than when you are very hungry (stomach growling/needing energy). This may limit "bottomless pit" overeating, sluggishness/lethargy after a meal and enhance energy/satiety after a meal.

  • Your body and brain need to be fuelled for a day of productivity as well as for any daily activity/exercise. You are the only person fuelling it, so don't ignore it's needs :)

  • Going to sleep on a full, heavy stomach may not be ideal for sleep or digestion. If you want to shorten any window of eating, slowing down on your fuelling 2-3 hours before sleeping may be more beneficial than limiting your morning fuel.


Warnings to consider when following a diet like IF:

  • Suppressing hunger signals in order to stick to a specific window of eating may lead to more difficulty in controlling the amount of food consumed as well as the type of food consumed.

  • IF focuses on the timing of eating rather than on which foods are eaten. Therefore, there is a risk of failing to achieve a healthy, balanced diet when following IF.

  • IF is not appropriate for someone with a history of disordered eating or currently healing their relationship with food.

  • There is a risk of increasing disordered eating or weight cycling by following any diet strategy that is not sustainable.

  • Limited evidence suggests that IF may lead to slightly greater losses in lean mass and compared to an energy-restricted diet. This can make weight maintenance more difficult due to a lower basal metabolic rate (energy/calories that you burn at rest).

  • Limited evidence also suggests that IF may lead to a lower quality of life and more adverse events compared to an energy-restricted diet.

  • A lower quality of life may be due to a pattern of eating that is too rigid and does not allow for social eating e.g. late dinners at restaurants.

  • Adverse events could be due to extreme hungers (feeling moody, headaches) or even feeling ravenous (e.g. feel physically ill, nauseous, dizzy) when sticking rigidly to a specific pattern of eating.


Conclusions:

  • The key to feeling great throughout the day, with no slumps, high hungers or cravings is to listen to your body's hunger cues and provide the nutrients and fuel that it needs.

  • Trying to fight against natural hunger cues in order to fit a specific pattern of eating/eating window is not something that will be sustainable.

  • When you do eat, make it count. Ensure that you provide your body with nutritious, energising, satisfying and sustaining meals. Focus on your diet quality (fibre, protein, energy, vitamins, minerals) as well as the quantity that your body requires and eat until you are satisfied, not uncomfortably full.

  • Adapt your eating to a pattern that works best for you, while allowing for sufficient nutrient intake and fuelling, as well as enjoyment and flexibility for social interactions.

  • An intermittent fasting approach may work for some, but not others. For those needing to manage weight/health that find it easier to eat within a shorter window, while still maintaining diet quality and appropriate quantities of food, IF or TRE may be a sustainable approach.


For personalised guidance in making healthy food choices or a meal plan to best suit your needs, book a consultation here: https://www.gabimeltzerdietician.com/book-online.


References:

  1. Templeman I, Smith HA, Chowdhury E, Chen YC, Carroll H, Johnson-Bonson D, et al. A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults. Sci Transl Med. 2021 Jun 16;13(598):eabd8034. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/34135111/

  2. Liu, D., Huang, Y., Huang, C., Yang, S., Wei, X., Zhang, P., Guo, D., Lin, J., Xu, B., Li, C. and He, H., 2022. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. New England Journal of Medicine, 386(16), pp.1495-1504.

  3. Pellergrini M, Cioffi I, Evangelista A, Ponzo V, Goitre I, Ciccone G, Ghigo E, Bo S. Effects of time-restricted feeding on body weight and metabolism. A systematic review and meta-analysis. Rev Endocr Metab Disord. 2020 March 21;17-33. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/31808043/

  4. Lowe DA, Wu N , Rohdin-Bibby L, Holliston Moore A, Kelly N, En Liu Y, 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 2020 Sep 28;180(11):1-9. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/32986097

  5. Harris L, Hamilton S, Azevedo LB, Olajide J, De Brún C, Waller G, Whittaker V, Sharp T, Lean M, Hankey C, Ells L. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database System Rev Implement Rep. 2018 Feb;16(2):507-547. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/29419624/

  6. Allaf M, Elghazaly H, Mohamed OG, Fareen MFK, Zaman S, Salmasi AM, Tsilidis K, Dehghan A. Intermittent fasting for the prevention of cardiovascular disease. Cochrane Database Syst Rev. 2021 Jan 29;1:CD013496. doi: 10.1002/14651858.CD013496.pub2. PMID: 33512717. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33512717/

  7. Cioffi I, Evangelista A, Ponzo V, Ciccone G, Soldati L, Santarpia L, Contaldo F, Pasanisi F, Ghigo E, Bo S. Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials. J Transl Med. 2018 Dec 24;16(1):371. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/30583725

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