Pros of Intermittent Fasting
Intermittent fasting is a dieting technique that is gaining in popularity. Intermittent fasting is a nutritional strategy that includes periods of caloric restriction and is interspersed with periods of normal or increased feeding (Harvie & Howell, 2016). Eating in such an abnormal pattern may seem counterintuitive to classic caloric restriction, but it seems to be an effective eating pattern, that could be extremely beneficial to people. There are two main types of intermittent fasting: time restricted feeding, where a person eats during a shorter period of the day (4-8 hrs) and abstains from food consumption for the rest of the day (16-20 hrs), and alternate day fasting ,where a person eats approximately 25% of their normal caloric intake two days of the week and maintains normal caloric consumption the rest of the week (Johnstone, 2014). Intermittent fasting is an effective weight loss strategy, may have higher levels of adherence, and promotes positive health outcomes (Harvie & Howell, 2016).
Intermittent fasting has been shown to be a viable technique in promoting weight-loss and improvements in obesity related measures. A meta-analysis by Tinsley and La Bounty (2015) found that alternate day fasting lead to reductions in body weight (3-7%), body fat (3-5.5 kg), total cholesterol (10-21%), and triglycerides (14-42%). Intermittent fasting affects glucose and lipid metabolism by changing the body’s fuel maintenance, which partially explains the diet’s efficacy. During a prolonged fast, free fatty acid mobilization, fatty acid oxidation, and ketogenesis increase, leading to the body to conserve glucose (Antoni, Johnston, Collins, & Robertson, 2017). These metabolic changes remain after the fast improving the body’s insulin sensitivity and reducing total adiposity. These changes may be independent of the caloric restriction aspect of intermittent fasting. Intermittent fasting could prove to be an effective strategy in improving body composition and weight. Traditional caloric restriction may be difficult for some dieters, and the benefits of positive changes in fuel metabolism make it easier to adhere to fasting because of perceived greater weight loss.
Some people adhere to a diet with an intermittent fasting protocol. Intermittent fasting protocols typically allow dieters to consume large amounts of the food they enjoy, do not restrict against certain types of macronutrients, and is conceptually simple when compared to certain diet protocols (Johnstone, 2014). It is obvious why fasting protocols are growing in popularity, and why it has a higher level of adherence. In a study of 107 overweight, pre-menopausal women, half followed a caloric restriction diet of 75% of their daily recommended caloric intake and half were on an alternate day fasting protocol, the subjects on alternate day fasting had a higher adherence rate than those on a caloric restriction diet at one (63% to 46%), three ( 43% to 37%) , and six (44% to 32%) month intervals respectively (Harvie et al., 2011). The women in this study following alternate day fasting also lost slightly more weight than those on the reduced calorie diet (-6.4 kg to 5.6 kg). The ability to enjoy the same food in normal amounts on most days, coupled with slightly greater weight loss, may explain why intermittent fasting has a higher adherence rate than caloric restrictive diets.
In addition to leading to positive changes in body composition and weight, and being simple to follow, intermittent fasting may have numerous health benefits. Intermittent fasting may protect people from a wide array of chronic diseases. The fasting aspect of intermittent fasting activates adaptive cellular stress responses, which signal pathways that optimize mitochondrial healthy functioning, repair DNA, and cleans out cellular debris (Mattson, Longo, & Harvie, 2017). This improved cellular functioning can help counteract the disease process of cardiovascular diseases, metabolic diseases, Parkinson’s disease, and Alzheimer’s disease. Rodent studies indicate that intermittent fasting may reduce the initiation of new tumors in cancer subjects by reducing the production of IGF-1, a hormone that promotes abnormal growth of cancer cells (Harvie & Howell, 2012). Intermittent fasting may be a viable eating strategy to prevent the onset of chronic diseases, slow the progressions of such diseases, or reduce their severity.
Intermittent fasting has many benefits for those who partake in periods of varying normal or slightly increased caloric consumption with time periods of caloric deficits. It is an effective weight loss strategy that positively impacts glucose and lipid metabolism. The diet protocol may be easier to follow than alternative energy restriction due to the dieter being able to enjoy the foods they enjoy and in larger amounts. Intermittent fasting could change cellular pathway responses, thus reducing the severity of chronic metabolic, neurodegenerative, cancerous, and cardiovascular diseases or lessen the chances of a person developing those diseases. People who employ intermittent fasting techniques, either through alternate day fasting or time restricted feeding, are following an effective diet plan, with many possible health benefits.
Antoni, R., Johnston, K. L., Collins, A. L., & Robertson, M. D. (2017). Effects of intermittent fasting on glucose and lipid metabolism. Proceedings of the Nutrition Society, 76(03),361-368. https://doi.org/10.1017/s0029665116002986
Harvie, M. N., & Howell, T. (2016). Could intermittent energy restriction and intermittent fasting reduce rates of cancer in obese, overweight, and normal-weight subjects? A summary of evidence. Advances in Nutrition: An International Review Journal, 7(4), 690-705. https://doi.org/10.3945/an.115.011767
Harvie, M. N., Pegington, M., Mattson, M. P., Frystyk, J., Dillon, B., Evans, G., . . . Howell, A. (2011). The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: A randomized trial in young overweight women. International Journal of Obesity, 35(5), 714-727. https://doi.org/10.1038/ijo.2010.171
Harvie, M., & Howell, A. (2012). Energy restriction and the prevention of breast cancer. Proceedings of the Nutrition Society, 71(03), 263-275. https://doi.org/10.1017/s0029665112000547
Johnstone, A. (2014). Fasting for weight loss: An effective strategy or latest dieting trend? International Journal of Obesity, 39(5), 727-733. https://doi.org/10.1038/ijo.2014.214
Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing Research Reviews, 39, 46-58. https://doi.org/10.1016/j.arr.2016.10.005
Tinsley, G. M., & LaBounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, 73(10), 661-674. https://doi.org/10.1093/nutrit/nuv041