Intermittent Fasting: Five Tips for Success
By now you’ve probably heard of intermittent fasting (IF) – or time restricted eating. Chances are you know someone who has incorporated this strategy into their daily or weekly life, eager to gain the health benefits touted in blogs, podcasts, and research studies. Or maybe you think of fasting as part of religious or spiritual observances, something you might have been doing your whole life.
There is no question interest in fasting has increased, although fasting actually has a very long history. Food hasn’t always been as plentiful and readily available as it is now. Our hunter-gatherer ancestors experienced fasting regularly – food was only available when they were able to kill or collect it.
Religious, spiritual, and cultural fasting practices have been observed for centuries. These fasts often vary in length and practices. Although some restrict food for shorter periods of time, others restrict only certain foods, and still others observe time restricted eating for days at a time. Some of the most well-known religious fasts are Islamic Ramadan and the Greek Orthodox Nativity, Lent, and the Assumption fasts. These and other religious and cultural fasts have been studied for their physical health effects – with promising results that have contributed to the examination of fasting as a potential therapy for a variety of metabolic concerns.1
Intermittent fasting strategies are associated with a variety of potential health benefits, many of which are thought to be the result of decreased oxidative damage and improved cellular stress resistance, leading to a healthy inflammatory response.2 Although much of the interest in intermittent fasting surrounds body composition changes – reduced body fat while maintaining muscle mass – fasting is also linked to decreased fatigue, improvements in mood, a more diverse gut microbiome, improved blood pressure, and enhanced insulin sensitivity.3-6
The evidence of potential benefits from longer term fasting is also growing. It is important to note, however, long term fasting with calorie restriction should be supervised by a qualified medical professional because unintended health effects can occur, especially in individuals with preexisting health conditions. Multiple day fasting-mimicking diets,7 which are rising in popularity and provide some daily nutrition while remaining very low calorie, fall into the long term category and should be closely supervised as well.
Here are five helpful tips for IF success.
1. Choose a Plan
If you’re thinking about incorporating intermittent fasting into your daily routine (and your doctor has given you the okay), there are several popular plans – 16:8 time restricted eating and 5:2 eating are the most common. Alternate-day fasting and 24-hour fasting are additional options, although these forms can be more difficult for some to stick to long term.
For the 16:8 time restricted plan, eating is restricted to an 8hour period, while the remaining 16 hours are spent fasting. Water, black coffee, and tea without milk or sweeteners are generally allowed during fasting periods. Often individuals will simply count backward from the time they normally eat dinner and go from there. For example, if you generally eat dinner at 7 p.m., then your first meal of the day would be at 11 a.m. More recent research suggests that shifting the eating period to earlier in the day and starting your meals around 8 a.m. might be more beneficial than eating later in the day.6
The 5:2 method restricts eating to five days per week with two days of fasting. With this method, up to 500 calories can be consumed on the fasting days, either as a single meal or spread out throughout the day. This method is generally less popular than 16:8 because some individuals feel very hungry or experience low blood sugar symptoms during the fasting days.
Alternate day fasting is basically what it says it is – a regular food consumption day alternates with a fasting day. With this approach, you eat every other day, except for up to 500 calories that can be consumed on fasting days.
The 24-hour fasting approach uses a 24-hour fast, from dinner to dinner the next day, or lunch to lunch, or breakfast to breakfast, whichever you chose. Essentially, if you normally eat dinner at 6 p.m., then you would not eat again until 6 p.m. the next day. Technically you are having a meal each calendar day, but there are 24 hours between meals, creating a more moderate length fasting period. This type of fast is usually done three days per week.
2. Consistency is Key
When starting an IF plan, being consistent with your eating times goes a long way to helping you successfully stick to the plan. If you know you have a weekly dinner with friends that never ends before 9 p.m., then choosing an 9 a.m.-5 p.m. eating schedule might not be the best choice, because you willl be constantly altering your fasting periods to maintain a 16:8 schedule.
As with any lifestyle change, take time to think through how it might affect your daily life, both short and long term, before getting started to minimize disruptions to your new habits. In general, it takes about three weeks to establish a new behavior and three months to cement it as a habit.
3. Avoid a Feast or Famine Mindset
A common trap with fasting is to develop a feast or famine mindset, where fasting times are offset by overeating and indulging in less than healthy foods. This is likely to erase any benefit you might obtain from fasting. In fact, alternating periods of fasting with periods of over indulgence can lead to weight gain, similar to yo-yo dieting, and become a cycle that is difficult to break. No matter which dietary pattern you choose, keeping treats and indulgences modest is always a good rule of thumb, especially when breaking a fast.
4. Partner IF with a Healthy Diet
The potential benefits of intermittent fasting can be increased when paired with a healthy diet, such as a traditional Mediterranean style diet (TMD). Research has shown that adherence to a TMD leads to greater intake of fiber, monounsaturated fatty acids, and micronutrients, and is more likely to meet adequate nutritional requirements for adults and children.8 An easy approach to Mediterranean style eating is to focus on eating whole foods – fresh vegetables and fruit, whole grains, healthy fats, and lean proteins. You can also incorporate avoidance of common allergens, such as gluten, into a modified Mediterranean diet.
Certain types of diets inherently provide fewer nutrients than a more balanced plan. Several popular diets have been studied to determine micronutrient deficiencies. In one study, Atkins, South Beach, and DASH diets were examined for micronutrient content and found to lack Recommended Daily Intake (RDI) for all 27 micronutrients studied. Of those 27 micronutrients, all of the diets were consistently low or completely lacking in biotin, vitamins D and E, chromium, iodine, and molybdenum.9
Another study found the Fast Metabolism Diet, a high animal protein plus low carbohydrate diet, tended to be low in vitamins B1, D, and E, and the minerals calcium, magnesium, and potassium. Eat to Live Vegan, a low calorie plant-based diet, was deficient in vitamins B12, B3, D, and E, as well as calcium, selenium, and zinc. While the Eat, Drink, and Be Healthy diet performed better in meeting RDIs, it was deficient in vitamin D, calcium, and potassium. Even when adjusted to a 2,000 calorie per day diet rather than low calorie, these diets all remained deficient in vitamin D.10
5. Consider a Supplement
Some people find that time-restricted eating leads to less food consumption in general. Although a nutritious diet in adequate amounts provides most of your daily nutrient needs, a supplement can help fill any nutritional gaps that occur, especially in the beginning when you are adjusting to your new lifestyle. As with any lifestyle change, it takes time to get the hang of things.
Along with the micronutrient deficiencies discovered in the previously mentioned studies, popular commercial diets also often lack omega-3 fatty acids and fiber. Consider Thorne’s Basic Nutrients 2/Day multi-vitamin/mineral, Super EPA omega-3 fish oil, and FiberMend to fill in nutritional gaps and support your health goals, regardless of the diet you choose.
- Trepanowski J, Bloomer R. The impact of religious fasting on human health. Nutrition Journal 2010;9(1):57. doi:10.1186/1475-2891-9-57
- Mattson M, Wan R. Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. J Nutr Biochem 2005;16(3):129-137. doi:10.1016/j.jnutbio.2004.12.007
- Domaszewski P, Konieczny M, Pakosz P, et al. Effect of a six-week intermittent fasting intervention program on the composition of the human body in women over 60 years of age. Int J Environ Res Public Health 2020;17(11). doi:10.3390/ijerph17114138
- Nugraha B, Riat A, Ghashang S, et al. A prospective clinical trial of prolonged fasting in healthy young males and females – effect on fatigue, sleepiness, mood and body composition. Nutrients 2020;12(8). doi:10.3390/nu12082281
- Rinninella E, Cintoni M, Raoul P, et al. Gut microbiota during dietary restrictions: new insights in non-communicable diseases. Microorganisms 2020;8(8). doi:10.3390/microorganisms8081140
- Sutton E, Beyl R, Early K, et al. Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metab 2018;27(6):1212-1221.e3. doi:10.1016/j.cmet.2018.04.010
- Wei M, Brandhorst S, Shelehchi M, et al. Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Sci Transl Med 2017;9(377). doi:10.1126/scitranslmed.aai8700
- Castro-Quezada I, Román-Viñas B, Serra-Majem L. The Mediterranean Diet and nutritional adequacy: A Review. Nutrients 2014;6(1):231-248. doi:10.3390/nu6010231
- Calton J. Prevalence of micronutrient deficiency in popular diet plans. J Int Soc Sports Nutr 2010;7:24. doi:10.1186/1550-2783-7-24
- Engel M, Kern H, Brenna J, Mitmesser S. Micronutrient gaps in three commercial weight-loss diet plans. Nutrients 2018;10(1). doi:10.3390/nu10010108