Intermittent fasting has become a popular way to lose weight, but going without food for 36 hours is a much more demanding approach than simply shortening the daily eating window. Research suggests that a prolonged fast can push the body towards using stored fat for energy, although that does not automatically make it the safest or most effective weight-loss method for everyone.A recent clinical trial and a separate case report have added more detail to what happens during longer fasting periods, while experts continue to warn that extreme restriction should not be treated as a routine diet plan.What happens during a 36-hour fast?When food is not coming in for an extended period, the body gradually uses available glucose and stored glycogen before relying more heavily on fat. This change can increase the production of ketone bodies, which are made when the body breaks down fat for fuel.A study published in Cell Metabolism examined strict alternate-day fasting, where healthy participants went through 36 hours without food followed by a 12-hour eating period. The four-week trial involved 60 people and found reductions in body weight and belly fat, along with changes in cholesterol and certain markers linked to inflammation.However, the researchers themselves described strict alternate-day fasting as one of the more extreme dietary interventions.Frank Madeo, a professor at Karl-Franzens University of Graz and an author of the study, said: “Strict ADF is one of the most extreme diet interventions, and it has not been sufficiently investigated within randomized controlled trials.”Longer fasting may increase ketones, but that is not the whole storyA separate case report published in 2024 looked at a twice-weekly 36-hour fasting routine over a much longer period. The report found that the approach was associated with sustained weight loss and a substantial rise in the ketone body beta-hydroxybutyrate after fasting.But the results were not a simple case of longer fasting being better. The researchers reported slower weight and fat loss under the 36-hour protocol compared with the shorter fasting approach they used for comparison.That is important because the metabolic switch towards fat use does not necessarily mean that someone will lose weight faster. Overall calorie intake, consistency and whether a person can actually maintain the eating pattern still matter.What is the safer approach to intermittent fasting?Experts have repeatedly pointed out that fasting does not need to mean going without food for a day and a half. Earlier research has also examined shorter fasting periods and approaches where people consume a limited number of calories on fasting days.Dr Elizabeth Lowden, a bariatric endocrinologist, told Healthline: “Different people may find it easier to do one or the other.”The Emily Program, an organisation focused on eating disorders and recovery, has also warned about possible problems linked with restrictive fasting. These can include hunger, fatigue, headaches, dizziness, digestive problems, mood changes, dehydration and nutritional deficiencies.James Betts, professor of metabolic physiology at the University of Bath, told The Guardian: “There [are] a lot of proposed benefits to [running on fats]. But a lot of the research hasn’t really [been borne out in] human beings. So we don’t see dramatic health benefits, certainly in the short term.”For someone considering intermittent fasting, the research therefore points towards a more practical message. A 36-hour fast can produce clear metabolic changes, but it is not a requirement for weight loss, and it should not be assumed to be suitable for everybody. People with medical conditions, a history of disordered eating or other health concerns should speak to a doctor before attempting prolonged fasting.Add 
as a Reliable and Trusted News Source
Add Now!
Read More News on
intermittent fastingfasting risksweight loss tipsdiet tipshealthy lifestyleeating habitscalorie deficit36 hour fasting
(Catch all the Business News, Breaking News, and Latest News Updates on The Economic Times.)
…moreless
Read More News on
intermittent fastingfasting risksweight loss tipsdiet tipshealthy lifestyleeating habitscalorie deficit36 hour fasting
(Catch all the Business News, Breaking News, and Latest News Updates on The Economic Times.)
Subscribe to The Economic Times Prime and read the ET ePaper online.
…moreless
