December 10, 2025, 2:15 pm | Read time: 4 minutes
Intermittent fasting, juice fasting, mimicking fasting, or therapeutic fasting–fasting is trending, and Rebecca Mir has discovered it for herself. The 33-year-old recently tried therapeutic fasting for five days and shared her experience on social media. FITBOOK reveals how the model fared with the fasting method and which week of the cycle Rebecca Mir recommends for women to fast.
“Therapeutic fasting day 5!!! And I have to say: I’m a little proud of myself for sticking with it,” Rebecca Mir revealed a few days ago in a post on Instagram. For five days, the host practiced therapeutic fasting, meaning she abstained from solid food. The hoped-for energy boost, often reported in the context of this fasting method, apparently did not materialize for Mir. All the more, she looked forward to breaking the fast at the end of the five days.
“Very exhausted and weak”
“I feel pretty… worn out. I no longer feel hungry, but I do have a slightly queasy stomach. Overall, I’m very exhausted and weak. Many have said, ‘Wait, the energy level will come.’ Unfortunately, it hasn’t happened for me yet–I really hope it will soon,” Rebecca Mir reported in a reel on day four of her fasting regimen. Mir was likely in the fasting phase where the withdrawal from food, especially substances like sugar, shifts to metabolizing fat (ketones) instead of glucose. This can be accompanied by weakness and even flu-like symptoms, a phenomenon also seen when transitioning to a ketogenic diet, known as the keto flu. I have reported on my personal experience with the keto diet and flu in the following FITBOOK article.
Therapeutic Fasting
The classic therapeutic fasting according to Buchinger prescribes several steps as part of the regimen. Therapeutic fasting begins with a relief day, during which one consumes a maximum of 1,000 kilocalories. On the first day of fasting, a bowel cleansing with Glauber’s salt is performed. During the fasting days, the intake of 50 to 500 kilocalories is recommended. This should be consumed with 250 milliliters of freshly cooked vegetable broth daily, 250 milliliters of freshly pressed juice (orange juice or vegetable juice), 20 to 30 grams of honey, and 2,500 milliliters of water and/or herbal teas.
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Breaking the Fast with an Apple
After the fasting period, it is not advisable to immediately return to your usual diet. On one hand, the fasting regimen can serve as a way to return to a more mindful daily routine, which includes fewer fatty, sweet, and heavy foods. On the other hand, it can overwhelm the body to handle a plate of pasta immediately after abstaining from solid food. Rebecca Mir is aware of this and wrote about breaking her fast: “Today I will break my fast in the classic way with an apple.
Just as important as fasting itself is the proper reintroduction to eating. After the apple, I will start slowly: soup, steamed vegetables–and then a little more each day. First potatoes, and by the second or third day, I want to eat normally again.” “Normal” for her apparently means healthy, balanced, and delicious. She also notes that she has acquired several new healthy recipes that she is very excited to try.
Tip for Women Who Want to Fast
Overall, therapeutic fasting seems to have been an enlightening experience for Rebecca Mir. She engaged with it intensively and therefore has a tip for women who want to fast. “Men can basically fast at any time. For us women, it’s unfortunately different because we should always consider our cycle–to avoid unnecessarily stressing the body,” Rebecca Mir explains in a post. “Especially the week before the period is rather unfavorable, as fasting during this phase can heavily burden the body and raise cortisol levels. On the other hand, the week after the period is very suitable–we generally have the most energy, feel stronger, and have significantly fewer cravings.”
Currently, research is divided on whether fasting could be disadvantageous for women. There are indications that fasting affects women’s sex hormones–possibly in a negative way.1,2 Additionally, there are scientists, such as Dr. Stacy Sims, who warn of the adverse effects of intermittent fasting on the cortisol levels of physically active women, especially during perimenopause and menopause. On the other hand, there are also various research indications of beneficial effects of fasting for both genders. Further research is needed to find definitive answers.
Our tip: Decide individually, ideally with medical advice, whether, when, and which fasting method is most suitable.