Over the last several years we have heard more and more about intermittent fasting. Intermittent fasting is a general term for diets that call for restricting caloric intake for certain periods of time. Without trying, everyone ends up having a fasting period because of our sleep cycle. Most of us go anywhere from 5-8 hours of fasting every night until we eat the next day. Other than the normal human overnight fast, there are other types of fasting as well.
One of the more common and doable intermittent fasts is the 16/8 fast. In this fasting method, a person would only eat during the 8-hour window while fasting following a 16 hour fast. During this 8-hour period, most people can fit at least 3 meals to meet calorie intake goals daily. A lot of people who skip breakfast already do this 16-hour fasting period. But for people who are regular breakfast-eaters, this fast could take some getting used to.
5 Days Regular/2 Days Fast
Another fasting variation can be eating regular meals for 5 days, then fasting for 2 whole days (restricting meals to 500-600 calories total). For example, someone might choose Tuesdays and Thursdays to fast, so on these days’ calories are restricted to 250 per day.
Another extreme example of intermittent fasting could be a 24-hour fast. Someone could eat regularly for a day, then at 8PM finish a meal, and not eat again until 8PM the following day. During this type of fast, it is very important to eat as you normally would on days that you aren’t fasting. This fast also requires a lot of mental strength because it’s hard for a person to go through a 24-period and not eat anything except for no-calorie drinks. These are just a few of the countless variations of intermittent fasting options that there are.
Effects of Intermittent Fasting
There has been a lot of research over intermittent fasting to better understand the possible negative and positive effects in the body. Some research has shown that intermittent fasting can affect human growth hormone in a 5-day and 2-day fast in a positive way. Increases in human growth hormone levels can lead to muscle gain and weight loss. Another benefit of intermittent fasting is that it can help improve insulin sensitivity. This can be helpful for people who have a higher sensitivity to insulin. Research showed that alternate day fasting in non-obese participants decreased insulin sensitivity in men and women. There is more research needed in order to better understand the long-term effects of the different types of intermittent fasting on different health markers.
Intermittent fasting can be varied for people who are wanting to try it because not one specific diet works for every person. If a person already skips breakfast regularly, then the 16/8 fast might work better for them than for someone who regularly eats breakfast. If someone wanted to challenge themselves, maybe fasting for 24-hours could be an idea. Either way intermittent fasting may be an effective way to improve body composition.
www.ncbi.nlm.nih.gov/pmc/articles/PMC329619/ GH research
Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man.
www.ncbi.nlm.nih.gov/pubmed/1548337 GH research
Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men.
www.ncbi.nlm.nih.gov/pubmed/15640462 Insulin sensitivity.
Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism.