So many pseudoscientific diets are out there these days, leaving many of us feeling stressed about the food we eat. There are “detox” cleanses, the ever-so-popular keto diet and one that just keeps going: intermittent fasting.
The basic premise is this: You eat during specific times, and fast during remaining hours or days. And the idea isn’t exactly new.
Dating back to the days of Hippocrates (around 460 to 370 B.C.) fasting was a form of treatment for seizures and other illnesses. Now, it’s made a comeback with claims that it helps you not only lose weight, but also be more alert and productive.
We talked with Kimberly Spatola, registered dietitian with Novant Health Heart & Vascular Institute about how the diet and what you need to know if you’re considering it.
What is intermittent fasting, and how is it done? The range of fasting varies per individual, but the typical interval ranges from eight to sixteen hours. Some fast for a window of a couple of hours a day to a full day a week.
Spatola explained that going without calories for prolonged stretches of time can put your body into a state of ketosis, similar to that of the keto diet, in which fat is burned instead of sugar for energy. This can lead to an increase in insulin sensitivity and decreased blood insulin levels. And, when insulin levels drop, so do your weight, cholesterol and blood sugar levels.
Until a few years ago, the most promising research on intermittent fasting only involved very fat rats. For humans, there wasn’t much research that showed it to be more effective than any other diet plan out there.
Additionally, Spatola said intermittent fasting could be dangerous — especially if you’re prone to eating disorders.
“There are a lot of things that can go wrong when you’re skipping meals and not eating enough,” Spatola said. “This is a slippery slope to disordered eating behaviors, since this requires to you avoid listening to your internal hunger and fullness cues.”
In early studies on mice or small groups of human subjects, fasting for 10 to 16 hours a day appeared to improve weight loss results, insulin levels, insulin sensitivity and blood pressure.
However, a larger study published in the New England Journal of Medicine in April 2022 revealed that intermittent fasting provided no significant benefits compared to simple calorie restriction. This study followed 139 men and women with obesity, who were split into two groups. All ate reduced-calorie diets, but one group consumed these calories only between 8 a.m. - 4 p.m.
All lost weight by the end of the year. But the difference between the fasting and non-fasting groups was deemed insignificant in terms of body weight reduction, waist circumference or risk factors like blood glucose levels, insulin sensitivity, blood lipids or blood pressure.
Bottom line: Spatola doesn’t recommend intermittent fasting as a solution for losing weight. While it might work for some, she said most of us can benefit from healthier eating patterns that aren’t necessarily too restrictive.
Short-term wins on fad diets almost always fade away. The most important way to see lasting results?
“Start changing your lifestyle by taking small steps to incorporate healthier habits into different areas of your life,” Spatola said.
That could mean walking for 30 minutes a day or substituting sugary juices with real fruit instead. Whatever it is, making incremental changes for the better can help you not just lose weight but keep you from yo-yoing back.
The only way to find out what works for you, Spatola said, is not through guesswork from internet research, but rather through an informed discussion with your provider on whether fasting would help you move a step closer toward a healthier lifestyle.