The idea of how much the amount of food we eat affects how long we live can be traced back to the Greek physician Hippocrates. In the excellent book Outlive: The Science and Art of Longevity, author Peter Attia talks of how food and health are related and cites the first person who put the idea of eating less into practice. A 16th century Italian businessman in Venice, who loved throwing parties and eating and drinking well, found himself suffering from weight gain, tummy aches and continual thirst, which is a symptom of incipient diabetes. To fix these issues, he went on a diet that consisted of eating just 340 grams of food per day, which was nourishing (like chicken stew) but not too filling. After a year of doing this, the Venetian found his complaints all gone and decided to stick to his diet. He lived well into his 80s and shared his secret to long life in Discourses on the Sober Life.
Today, focussing on how much and when we eat has become the most popular route to taking control of one’s health and weight; we call it intermittent fasting. Intermittent fasting is one of the most trending “dieting” techniques currently. “It is an eating pattern rather than a diet and has gained significant popularity in recent years due to its potential health benefits and its compatibility with various lifestyles,” says Bhakti Samant, chief dietician at Kokilaben Dhirubhai Amabani Hospital, Mumbai.
Intermittent fasting entails eating all your meals within an 8- to 12-hour window and fasting for between 12 to 16 hours every day, explains Dr Anurag Aggarwal, consultant for internal medicine at Fortis Escorts Hospital in Faridabad. “Intermittent fasting cycles between periods of eating and fasting and doesn't specify which foods to eat but rather when to eat them,” he adds.
Intermittent fasting is a great way to lose weight because it leads to calorie restriction and also offers other health benefits such as improved metabolism, enhanced cellular repair, and potential reduction in the risk of certain diseases. Unlike several fashionable diets currently, intermittent fasting doesn’t focus on specific food types, making it simpler for people to follow. Its flexible nature also allows individuals to adapt to the fasting period to suit their lifestyles, adds Aggarwal. Add to that the fact that most people do not want to put in the hard work (like committing to exercise and work out) and prefer to take a short cut to becoming ‘fit’, which is synonymous with ‘losing weight’ and you will see why intermittent fasting is gaining popularity.
However, while losing weight might be good for your overall health, depriving yourself of nutrition by sticking to intermittent fasting over long periods of time could be harmful and risky. Following calorie restriction routines such as intermittent fasting over long periods of time means losing out on multiple fronts as far as nutrition is concerned.
Attia, in his book, points out that there are dangers to calorie restriction approaches [in strategies like intermittent fasting] over the long term because the body isn’t getting enough food. “Long-term intermittent fasting may pose certain risks, including nutrient deficiencies, changes in hormonal balance, potential negative impacts on mental health, and adverse effects on certain individuals, such as those with eating disorders or underlying health conditions,” warns Aggarwal.
Furthermore, extended fasting periods of durations up to 20-22 hours can lower glucose levels and stress the body excessively, says Dr. Sushila Kataria, senior director, internal medicine at Medanta Hospital in Gurugram. “Long term intermittent fasting can have adverse effects on the heart, especially for individuals with chronic conditions like diabetes, liver, or kidney diseases. Also, indiscriminate eating during fasting, consuming excessive sugar or unhealthy foods, may negate the benefits for weight reduction and overall health,” adds Kataria.
Your aim ought to be to get fit and healthy, not weight loss. That means intermittent fasting alone is not the answer. “Intermittent fasting alone might not be enough to achieve all health and fitness goals. It is not a magic solution and individual results can vary based on factors including age, gender, activity levels, and overall health. While it can be a valuable tool for weight management, improved insulin sensitivity, cardiovascular health, and overall health, it's essential to combine it with a balanced diet, regular exercise, and other healthy lifestyle practices,” advises Samant.
For those who stick to intermittent fasting, getting enough protein in your system within a limited eating window—important for muscle growth—can be challenging. “Bodybuilders, athletes, and those with muscle-building goals often prefer a more traditional meal schedule to support their training and recovery. Intermittent fasting can affect athletic performance, especially if you train intensely and need loads of energy before, during, and after workouts. If one is not careful about their food choices during the eating windows, intermittent fasting can lead to nutrient deficiencies. It’s essential to consume a balanced diet that includes a variety of nutrients for overall health,” warns Samant.
Moreover, the safety and sustainability of intermittent fasting can vary from person to person, depending on individual factors such as overall health, goals, and lifestyle. While intermittent fasting is generally considered safe for most people in the short term, it might not be suitable for you if you have any underlying health conditions or concerns. Following an extremely restrictive form of fasting for an extended periods could lead to nutrient deficiencies and can be stressful on the body. It’s crucial to pay attention to your stress levels and overall well-being and not just your weight and body fat percentage.
Shrenik Avlani is a writer and editor and the co-author of The Shivfit Way, a book on functional fitness.
