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Is intermittent fasting really good for you? 6 questions answered.
Intermittent fasting (IF), an eating pattern that cycles between periods of eating and fasting, has gained popularity as a simple yet often effective way to manage and lose weight. But is it as beneficial as it seems? Researchers have connected the practice to weight loss, but have also raised questions about its benefits over long periods of time. Here are six key questions – answered – about IF benefits, risks, and what to consider before trying it.
1 | What are some different forms of intermittent fasting?
There are many different forms of IF. IF can look like eating only on certain days of the week, only eating certain amounts on certain days of the week, and only eating within certain windows of time every day (time-restricted eating).
Different forms of IF include, but are not limited to:
- Fast for 16 hours and eat within an 8-hour window (this is an example of time-restricted eating)
- Fast for 12 hours and eat within a 12-hour window (this is another example of time-restricted eating)
- Eat in your typical way for five days, then eat only 500-600 calories on two non-consecutive days per week
- Eat only one big meal per day within a short window
2 | Do people usually lose weight with intermittent fasting?
Yes. An analysis of research on intermittent fasting shows that all IF forms can significantly reduce body weight compared to typical diets.
“Overall, a lot of analysis agrees that different forms of IF can lower calorie intake even if people aren’t counting calories – that’s the good part,” said Dr. Brad Lipson, a physician and principal investigator on obesity and diabetes clinical trials with Care Access. "The bottom line is that IF can help people eat fewer calories than they burn, which is the core thinking behind weight loss."
3 | Which forms of IF are the best for weight loss?
Despite extensive research, it's not clear if one form of IF is universally better than others for weight loss. Rather, doctors often work with their patients to figure out which form of IF works best for them as an individual.
“Some people might prefer to eat during the work day because they’re burning energy, while some people might prefer to eat after the work day,” Dr. Lipson said. “It can kind of be customized for the person’s lifestyle. That's where a doctor comes in, to help someone customize an IF plan based on that person's needs, desires, goals, and even cultural background and food preferences.”
4 | Can IF really improve long-term health?
Not necessarily. Per an analysis of research on time-restricted eating, most studies show that restricting eating with IF in an 8-hour window can actually hurt someone's long-term health. People who restricted eating to 8-hour windows were at a higher risk of dying from heart or blood vessel related problems. While it's not clear why those people were at higher risk for those issues, ultimately more research is needed on whether IF can provide long-term health benefits beyond initial weight-loss results.
"One thing to consider is that the quality of the food you eat affects long-term health, regardless of pure calories in and calories out," Dr. Lipson said. “If you do IF and you eat fast food all the time, that’s not ideal. The timing and amount you’re eating may be good, but you still need to look at what you’re eating. So if someone chooses a form of IF that is sustainable for them in the long-term, that focuses on mostly healthy food such as the Mediterranean diet, then IF may help some people improve their long-term health.”
5 | Can anyone try IF?
Not necessarily. It can be potentially unsafe for people with certain health problems, and everyone should consult with their physician before trying IF.
“IF could possibly trigger eating disorders in people who have struggled with that,” Dr. Lipson said. “It can also create issues during pregnancy and breastfeeding; for example, a baby may not get enough nutrients to grow well in the womb, and a mother may not get enough energy to make a good amount of milk for breastfeeding. Lastly, someone with type 2 diabetes could end up with dangerously low blood sugar.”
6 | What should I keep in mind if I’m thinking about trying IF?
“It’s definitely an effective approach for weight loss, but you have to look at whether it’s really sustainable – can you do it for more than a few weeks?” Dr. Lipson said. “Also, can you restrict your eating windows while also choosing to eat healthier foods? Overall, it’s a marathon, not a sprint. It could take months to get significantly healthier for the long-term. Make sure your approach is sustainable.”
CONTRIBUTING EXPERT
Brad Lipson, DO
Dr. Lipson is a board-certified Family Physician with 20 years of clinical experience. He serves as a Principal Investigator at various clinical research sites affiliated with Care Access, dedicated to advancing medical treatments in areas such as obesity and diabetes.
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