Intermittent Fasting – Truth or Hype?
Intermittent Fasting – Truth or Hype?
Intermittent fasting is finishing up as one of the top eating trends of 2018. Chances are that you have heard of this diet, and possibly tried to incorporate it into your daily lifestyle. But does research support the media hype, or is it just the latest fad in the 60-million-dollar weight loss industry? And is this form of eating sustainable, or will it just end up as a trend of the past?
What is it?
Intermittent fasting is an alternative to traditional calorie restriction that utilizes extended times of overnight fasting to decrease daily caloric intake. This diet is popular for weight loss because it doesn’t involve specific food groups or counting calories or macronutrients. It does require abiding by a strict schedule regarding when you eat. The most well –known forms of intermittent fasting are alternate-day fasting (ADF), the 5:2 diet, and time restricted feeding (TRF). ADF consists of one “fast” day of 25% of your usual food intake (approximately 500 calories), followed by one “feed” day of ad libitum eating. The 5:2 diet is like ADF, although fasting only occurs 1-2 days per week. Time restricted feeding (TRF) is the newest form of intermittent fasting, which restricts subjects to a feeding window, usually 8 hours within the day. Food intake is ad libitum, without specific food restrictions or calorie counting during the allotted time period. The “fasting window” lasts approximately 16 hours, and the only intake allowed is calorie free beverages such as water, tea, black coffee and diet drinks.
The evidence shows…
The initial hype on the health benefits of intermittent fasting was primarily based on animal or laboratory research. Much of the current human studies clearly indicate that a higher level of evidence is required to provide actionable nutrition recommendations for weight loss1. Of the recent human trials that have been conducted, alternate day fasting does not appear to produce superior weight loss to simple calorie restriction234. Currently, research is very limited on time restricted feeding, in which individuals only eat within an 8-hour time window and fast then fast for 16 hours. A 2018 study in the Journal of Nutrition and Healthy Aging found that 8-hour time restricted feeding did lead to mild caloric restriction and subsequent weight loss. The findings indicate that reducing the daily eating window to 8 hours decreased caloric intake by approximately 300 calories per day, without intentional calorie counting. Due to this energy deficit, subjects did lose weight compared to controls. This study had many limitations, however, including study design and sample size (23 participants). These preliminary data offer promise for the use of time restricted feeding as a weight loss technique in obese adults, but longer-term, larger-scale randomized controlled trials will be required before solid conclusions can be reached5.
Is it so simple?
Part of the appeal of intermittent fasting is in its theoretical simplicity. But dieter beware, this eating trend does not come restriction free. Putting a time limit on when you can eat may infringe on your social life and time spent sharing meals with family and friends. Long periods of food restriction in the morning may result in overeating at your first meal of the day and subsequent blood sugar crashes. Evidence also suggests that humans burn more calories and digest food best in the morning6, at a period when time restricted feeding suggests you fast. The bottom line is that none of the weight effects of any diet matter if you cannot stick with the protocol long term. Are you willing to follow this plan for the rest of your life? If not, then it’s likely not a sustainable approach to weight loss.
Effects on Disease
Research continues to evolve on the effects of intermittent fasting on other disease states and metabolic markers. Interested in learning more about intermittent fasting as it relates to digestive disease and disorders, cardiovascular risk factors, diabetes or other health issues? Schedule an appointment with our registered dietitian to learn the facts on this eating trend as related to your health.
Visit us at www.compgihealth.com or call today at 224-407-4400.