What Is 'Fake Fasting'? All About Diet Plan That Promotes Weight Loss With Age-Reversing Benefits

'Fake fasting' is a type of fasting where a person consumes only water, avoiding all food, supplements and medications. This practice has gained popularity for its health benefits, including weight loss, improved insulin sensitivity and cellular repair. It is also known as water-only fasting or fasting mimicking diet (FMD).

As the name signifies, the diet plan includes mimicking the effects of water fasting by targeting blood glucose, ketone levels and other biomarkers. In normal fasting, people don't eat anything. However, fake fasting involves consuming specific nutrients in cycles in limited amounts.

The benefits of the diet were mentioned in a peer-reviewed study published in Nature Communications in 2024. Researchers noted that FMD is a five-day diet high in unsaturated fats and low in overall calories, protein and carbohydrates. It is designed to mimic the effects of a water-only fast while still providing necessary nutrients and making it much easier for people to complete the fast.

USC Leonard Davis School Professor Valter Longo, who is also the senior author of the new study, developed the diet. "This is the first study to show that a food-based intervention that does not require chronic dietary or other lifestyle changes can make people biologically younger, based on both changes in risk factors for ageing and disease and on a validated method developed by the Levine group to assess biological age," Longo said in a statement.

To conduct the study, researchers analysed the diet's effects in two clinical trial populations, each with men and women between the ages of 18 and 70.

Patients who were randomised to the fasting-mimicking diet underwent 3-4 monthly cycles. They followed FMD for five days, then ate a normal diet for 25 days.

The FMD included plant-based soups, energy bars, energy drinks, chip snacks, tea, and a supplement providing high levels of minerals, vitamins, and essential fatty acids for five days.

The study found that patients in the FMD group had lower diabetes risk factors, including less insulin resistance and lower HbA1c results. "This study shows for the first time evidence for biological age reduction from two different clinical trials, accompanied by evidence of rejuvenation of metabolic and immune function," Longo said.

"Although many doctors are already recommending the FMD in the United States and Europe, these findings should encourage many more healthcare professionals to recommend FMD cycles to patients with higher than desired levels of disease risk factors as well as to the general population that may be interested in increased function and younger age," Longo said.

Does FMD reduce dementia signs?

In 2023, a study published in the National Library of Medicine analysed the potential of FMD in preventing and treating Alzheimer's disease (AD). The study found improvements in AD biomarkers, cognitive functions and subjective well-being measures in humans following FMDs.

"However, the optimal duration and frequency of FMDs and their long-term safety and efficacy remain to be determined," the study noted.