Food fads come on and go. Remember the cabbage soup diet? The macrobiotic diet? Or my favorite: drinking man’s diet?
Many fad diets have been debunked as lacking in vital nutrients or just plain not sustainable for the long term. Some, however, are based on solid research and actually work. Good examples include the DASH diet (Dietary Approaches to Stop Hypertension) and the Mediterranean eating plan.
What about intermittent fasting?
Unlike some fad diets, this one has actually been studied, though most of the research to date is on animals.
Intermittent fasting (IF) is basically a way to lose weight by not eating (or eating very little) on certain days or fasting at certain times of the day. According to a review on the topic by registered dietitian and associate clinical professor Dana Angelo White of Quinnipiac University, one common method of intermittent fasting is to fast (consume no calories or very few) on certain days of the week alternated with other days of normal eating. A modified version of this involves fasting say, two days a week (not in a row) and eating normally on the other five days.
Another popular version of intermittent fasting is to only eat during limited hours of the day. One example is the 16:8 plan; dieters go without calories for 16 hours a day and only eat during an eight-hour window. For instance, a person might eat between 8 a.m. and 4 p.m. or noon to 8 p.m. After that, stay out of the kitchen.
Some people like these plans because it’s easier to be all or nothing than to count calories every day.
But do they work?
While weight loss on these diets is similar over time to straight calorie counting, researchers have seen other benefits to not eating for longer time periods, especially during the evening and night hours.
For example, when we eat and fast in line with the body’s natural rhythm (basically eat when the sun is up and fast when it goes down), we may expect better control of our hunger, more loss of body fat and overall weight loss.
On alternate day fasting regimens, the days of complete fasting can be challenging, however. Research volunteers have reported feeling extremely hungry and irritable on fasting days, which may explain why we might not be willing to follow this pattern very long.
What about people with diabetes, who need to keep blood glucose levels from going dangerously high or low? Experts generally discourage people with Type 1 diabetes or Type 2 diabetes who require insulin from following an intermittent fasting plan. Others who shouldn’t attempt extended fasting include individuals who suffer with hypoglycemia (low blood sugar), pregnant or breastfeeding women and people who need to take medications with food.
Best advice as we wait for more human studies to emerge? Consult with your medical provider and a skilled nutrition professional to make sure you know what you’re doing before embarking on an intermittent fast.
Barbara Quinn is a registered dietitian and certified diabetes educator affiliated with Community Hospital of the Monterey Peninsula. She is the author of “Quinn-Essential Nutrition” (Westbow Press, 2015). Email her at email@example.com.