Intermittent Fasting For Weight Loss

Have you thought about using intermittent fasting to improve your weight loss? Intermittent fasting involves alternating between periods of severe and intentional energy restriction and periods of regular eating. It has been assumed that intermittent fasting can be an effective way to reduce body weight and improve body composition due to extending the period an individual’s body has to burn fat as opposed to calories that have just been eaten. Before adding this way of eating to your lifestyle, it’s important to know the current research regarding the effectiveness of intermittent fasting on weight loss.

What are the different types of intermittent fasting?

There are a variety of different intermittent fasting types, however the most common are the 5:2, 16:8, and 12:12 methods. During the 5:2 method, individuals eat approximately 20% of their estimated energy requirements two nonconsecutive days of the week (such as Monday and Thursday) and all estimated energy requirements the remaining days of the week. In the 16:8 intermittent fasting method, individuals eat all estimated energy requirements within 8 consecutive hours during the day and then fast the remaining 16 hours. The 12:12 intermittent fasting method is similar to the 16:8 except individuals eat during a 12 consecutive hour timespan and fast for the remaining 12 hours.

Do research studies show that intermittent fasting is more effective for weight loss?

Currently, studies can not determine whether intermittent fasting is more effective than continuous caloric restriction in improving body composition.^1,2,3,4,5 Most studies showed no significant difference in body mass index (BMI) and body weight between the intermittent fasting groups and continuous eating groups. The restricted feeding times provided through intermittent fasting may cause some individuals to eat less calories during the day than they normally would which may lead to higher decreases in body weight and body mass⁵, however this is not guaranteed. Intermittent fasting that was paired with exercise did show more significant improvements on BMI and weight loss than intermittent fasting alone.⁶ However, it has not been determined which type of exercise should be paired with intermittent fasting for the best results.

Should I start using intermittent fasting to lose weight?

Since the results are currently undecided regarding the effectiveness of intermittent fasting for weight loss, it comes down to your preference. If you prefer having an eating window in order to avoid eating excess calories (such as through mindless snacking), intermittent fasting may be appropriate for you. However, keep in mind that consistency is key. If you are not adhering to this eating structure, you may affect your results as well as your consistency for building a routine. If you are already planning on having “days off” from your intermittent fasting weekly, this may not be the eating structure for you.

Whether you choose to use intermittent fasting or not, it is important that you still focus on eating nutrient-dense foods with proper portion sizes. If you would like guidance on intermittent fasting, nutrient-dense foods or just on ways you can start to eat healthier, please feel free to schedule a 45-minute nutrition coaching session with me here.

References:

1. Witjaksono F, Prafiantini E, Rahmawati A. Effect of intermittent fasting 5:2 on body composition and nutritional intake among employees with obesity in Jakarta: a randomized clinical trial. BMC Research Notes. 2022;15(1):1-7. doi:10.1186/s13104-022-06209-7.

2. Keenan SJ, Cooke M, Hassan EB, et al. Intermittent fasting and continuous energy restriction result in similar changes in body composition and muscle strength when combined with a 12 week resistance training program. Eur J Nutr. 2022:61(4):2183-2199. https://doi.org/10.1007/s00394-022-02804-3 Accessed June 8, 2023.

3. Schubel R, Nattenmuller J, Sookthai D, et al. Effects of intermittent and continuous calorie restriction on body weight and metabolism over 50 wk: a randomized controlled trial. Am J Clin Nutr. 2018;108(5):933-945. doi:10.1093/ajcn/nqy196

4. Ribeiro DE, Santiago AF, de Abreu WC. Continuous energy restriction (CER) plus 16/8 time-restricted feeding improve body composition and metabolic parameters in overweight and obese, but no more than CER alone. Nutr Healthy Aging. 2021;6(2):147-156. doi:10.3233/NHA-200106

5. Kotarsky CJ, Johnson NR, Mahoney SJ, et al. Time-restricted eating and concurrent exercise training reduces fat mass and increases lean mass in overweight and obese adults. Physiol Rep. 2021;9(10):1-17. doi:10.14814/phy2.14868

6. Batitucci G, Faria Junior EV, Nogueira JE, et al. Impact of intermittent fasting combined with high-intensity interval training on body composition, metabolic biomarkers, and physical fitness in women with obesity. Front Nutr. 2022;9. doi:10.3389/fnut.2022.884305