Intermittent fasting has boomed in popularity over the last few years. Not only has it been a trendy TikTok topic – it has also been an area of interest for physicians and nutritionists.
It has been hailed as an effective weight-loss strategy and there is some evidence that suggests it may reduce inflammation. But it may not be right for everyone, and it’s not a magical solution for weight loss. We spoke with Mary Sabat, MS, RDN, LD, a nutritionist and owner of BodyDesigns and we summarized all of the key information you need to know about intermittent fasting so you can make the best decision for your health and wellness.
What is intermittent fasting?
Sabat defines intermittent fasting as, “an eating pattern that cycles between periods of fasting and eating. It does not specify which foods to eat but rather when to eat them.”
One of the benefits of intermittent fasting is that if you are eating within a smaller window of time, you are going to be eating fewer calories. The Mayo Clinic says that this is about as effective as a low-calorie diet – which makes sense, as a calorie deficit is key for weight loss.
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How long should you do intermittent fasting?
Sabat says there are a few different approaches to intermittent fasting. She outlines them in detail:
- 16:8 Method: This method involves fasting for 16 hours every day and restricting your eating window to 8 hours. Typically, this means skipping breakfast and consuming all your daily calories within an 8-hour window, such as between 12 pm and 8 pm.
- 5:2 Diet: With this approach, you eat normally for five days of the week and reduce your calorie intake to around 500-600 calories on the remaining two days. These fasting days are not consecutive but rather spaced throughout the week.
- Alternate-Day Fasting: As the name suggests, this method involves fasting every other day. On fasting days, you either consume no calories or limit your intake to around 500 calories.
Sabat says which one to follow depends on the individual. “The specific duration that works best for you may depend on your preferences and how your body responds. I personally like to use a 14-hour fast with everyone, especially women, but I will recommend a longer fast for men or someone who is very overweight and insulin resistant,” she explains.
What are the negatives of intermittent fasting?
Sabat stresses that intermittent fasting can be a tool for some people, but it is not right for everyone. “Certain groups, such as pregnant or breastfeeding women, individuals with a history of disordered eating and those with certain medical conditions, should exercise caution or avoid it altogether. I personally look at whether the person is stressed and might be producing too much cortisol, whether they are male or female and activity level. Intermittent fasting, especially for women, can spike cortisol higher leading to more weight gain,” she explains.
Intermittent fasting may also have some side effects. The Mayo Clinic cautions that the following may occur with intermittent fasting:
- Hunger
- Fatigue
- Insomnia
- Nausea
- Headaches
Overall, Sabat notes intermittent fasting shouldn’t replace a healthy lifestyle. “Intermittent fasting may be worth considering for both health and weight loss goals, but it’s not a magic solution,” she says. “If practiced consistently and combined with a balanced diet and regular physical activity, it may contribute to certain health improvements. However, individual results can vary, and it’s important to approach it as part of an overall healthy lifestyle.”
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