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?
Usually when our bodies signal hunger, but sometimes even without any hunger. Consider the following:
Eating at milder hunger cues (when you feel like your stomach is slightly empty and you could eat) rather than when you are extremely hungry or ravenous (moody, headachey, lethargic, gnawing emptiness in your stomach) may limit "bottomless pit" overeating, sluggishness/lethargy after a meal and enhance energy/satiety after a meal.
Sometimes your busy work day may not fit in perfectly with your body's natural hunger signals. In this case, you may need to eat at planned times rather than hungry times in order to suit your work schedule.
Your body and brain need energy to function, to be productive as well as for any daily activity. You are the only person fuelling it, so don't ignore it's needs :)
Lying down or going to sleep soon after eating may not be ideal for digestion. Adjust your eating time if needed to feel comfortable and get a good night sleep :)
Warnings to consider when following a diet like IF or any diet for that matter:
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 and may lead to binge-type eating.
Intermittent fasting focuses on the timing of eating and takes away any trust in relying on your body's own signals for hunger.
Intermittent fasting may also limit opportunity for nutrition by having less meal opportunites.
Intermittent fasting 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.
Conclusions:
The key to feeling great throughout the day, with no slumps, high hungers or cravings is to tune back in to your body's needs & listen to it's hunger and fullness/satiety cues.
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. 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 as well as enjoyment, satisfaction and flexibility.
For personalised guidance in letting go of the diet mentality once and for all, feeling your best and learning to build nutritious, satisfying and energising meals, book a consultation here: https://www.gabimeltzerdietician.com/book-online.
References:
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/
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.
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/
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
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/
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/
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