There was a time when I was trying to lose weight and, like many of us, had begun to feel overwhelmed by the advice around me. Eat less. Count calories. Exercise more. Try this diet. Avoid that food.
And then someone suggested fasting.
I remember wondering: Does simply not eating really help? Is fasting actually good for the body, or is it just another way of restricting food?
That question sent me back to something much closer to home.
In India, fasting has never been a new-age health trend. Long before we counted fasting hours or tracked calories and glucose, our traditions already had their own rhythms of restraint and abstinence: Ekadashi, Navratri, Mahashivratri, Janmashtami and countless regional observances.
But as I looked more closely, I realised that the traditional idea of fasting was far more nuanced than simply “not eating”.
Upavasa is traditionally associated with drawing closer to the Divine. Vrata is a disciplined vow or observance, often involving restraint, while Niyama brings the element of conscious discipline. Ayurveda adds another dimension through Agni, our digestive and metabolic capacity, and Langhana, the principle of lightening the body’s physiological load.
Fasting, therefore, was never simply about how long one could go without food. It was about restraint, awareness and suitability.
The rules, of course, were never identical. Some traditions involved complete fasting; others allowed fruits, milk, nuts or a simple meal. Certain foods were avoided, particular times observed, and the mind was deliberately drawn away from ordinary indulgence.
The underlying idea was simple: Sometimes, the body and the mind benefit from a pause. Today, modern science is beginning to examine what happens physiologically when we fast, though in very different language.
Ekadashi: Why Are Grains Traditionally Avoided?
Ekadashi falls on the 11th lunar day of both the waxing and waning fortnights and is among the most widely observed fasting traditions in Hindu practice.
It is not simply a day of eating less. In many traditions, rice, wheat, other cereals and pulses are avoided, while fruits, roots, tubers, milk, nuts and foods such as amaranth, buckwheat (kuttu) and water chestnut (singhara) may be consumed, depending on the particular observance.
Why grains? Traditional explanations connect Ekadashi with the lunar cycle and with maintaining a lighter state of body and digestion. One widely circulated explanation relates the Moon’s influence on bodily water and considers grain-based foods less appropriate during this period.
Modern science, however, does not establish that lunar gravity creates an “internal tide” in the human body or that grains absorb bodily water in this way. That distinction is worth preserving.
Traditional practices do not become meaningless simply because every traditional explanation cannot be demonstrated through modern physiology. Equally, ancient practices need not be dressed up in scientific language to make them respectable. What modern science can tell us with greater confidence is what happens when food intake stops.
What Happens When We Fast?
After a meal, the body primarily uses readily available glucose for energy. As the fasting period progresses, insulin levels generally fall, glycogen stores are gradually used and the body increasingly draws on stored fuel. Fat mobilisation rises and, with longer periods without food, ketone production increases.
The body is not simply “switching off”. It is changing how it uses fuel. This metabolic flexibility is one reason fasting has attracted so much scientific interest.
Our metabolism also follows a circadian rhythm. Glucose regulation, insulin sensitivity and several metabolic processes vary across the day. Modern research into time-restricted eating is therefore looking beyond calories to the relationship between food intake and the body’s internal clock.
Recent research suggests that time-restricted eating can produce modest improvements in body weight, waist circumference, fat mass and some metabolic markers, although results vary and fasting does not consistently outperform conventional calorie restriction.
So fasting may help, but longer is not automatically better.
Does Fasting Slow the Metabolism?
This is where popular fasting advice often becomes misleading. A 12-hour overnight fast is not the same physiological experience as several days of severe calorie restriction.
With prolonged or substantial energy restriction, energy expenditure can decline through both weight loss and metabolic adaptation. The body becomes more economical when energy remains scarce. This does not mean fasting permanently “damages” metabolism. Nor does it mean fasting automatically “boosts” it.
What matters is the context: how long, how much, how often, whether nutritional needs are being met, and the individual practising it.
Why Does Weight Lost at Detox Centres Often Come Back?
Many people have experienced this pattern: several days at a fasting or detox programme, very little food, a dramatic drop on the weighing scale, and then a gradual return to the old weight once normal life resumes.
The first point to understand is that weight loss is not the same as fat loss.
When food intake falls sharply, particularly when carbohydrates are reduced, glycogen stores decline. Because glycogen is stored along with water, some of the initial weight lost is water. There is also simply less food within the digestive tract.
Some body fat is certainly lost when energy intake falls substantially below expenditure, but the early change on the scale can therefore look much more dramatic than the actual reduction in fat.
Once normal eating resumes, glycogen, water and digestive contents return. And if nothing fundamental has changed in eating habits, physical activity, sleep or overall energy intake, the lost fat can return too.
A dramatic seven-day result, therefore, tells us much less than what happens six months later.
What About Muscle? Does Fasting Burn Muscle?
There is another reason the number on the scale can be misleading: what we lose matters as much as how much we lose.
Aggressive or prolonged energy restriction can result in loss of lean tissue. The body does not use only fat for energy, and studies of time-restricted eating have reported modest reductions in lean mass in some settings.
But the outcome depends greatly on how fasting is practised.
Adequate protein and regular resistance or strength exercise can help preserve muscle. Healthy weight management should not simply mean making the number on the scale smaller.
The goal is to lose excess fat while preserving strength and muscle.
That becomes particularly important with increasing age, when maintaining muscle is essential for strength, mobility and metabolic health.
Ayurveda’s Idea Was Not “Starve Yourself”
This is where the traditional perspective offers an important distinction. The Ayurvedic concept of Langhana, or lightening, may involve reducing food quantity, simplifying meals or choosing foods that are easier to digest. It is not synonymous with prolonged starvation; its application depends on the person’s condition, digestive capacity and overall strength.
This brings us back to Agni. If digestion is already burdened, continually adding more food may not necessarily be helpful. A temporary reduction in dietary load may, in appropriate circumstances, be considered supportive.
The Ayurvedic question, therefore, is not: “How many hours can I survive without food?” It is: “What is appropriate for my body, my digestion and my circumstances?” That principle of individual suitability remains remarkably relevant.
Navratri: Nine Days, Many Traditions
I observe both Chaitra Navratri and Sharad Navratri, and for me, the experience has always been about more than changing the menu.
There is a conscious stepping away from the ordinary rhythm of eating; a period of restraint, reflection and greater awareness.
Across India, however, there is no single Navratri fasting diet. Depending on region and tradition, fasting foods may include kuttu, singhara, rajgira, sama, sabudana, makhana, fruits, roots, potatoes, dairy, nuts and seeds. The precise rules vary between communities, families and individual observances.
The principle remained constant even when the plate changed. Food was adapted to locality, season, culture and custom rather than reduced to one universal formula.
Chaitra Navratri arrives in spring; Sharad Navratri marks the autumnal transition. Today, chronobiology is examining how eating patterns interact with the body’s internal clock and metabolic rhythms.
The science is new. The Indian intuition that food, time, season and the individual belong together is much older.
Is Fasting Good for Digestion?
It can be, but not because the digestive system needs a periodic “detox”.
For someone accustomed to frequent snacking, late-night eating or almost continuous calorie intake, establishing a defined eating period may reduce overall intake and create a more regular rhythm. A period without food also means the digestive system is temporarily not processing another meal.
That is different from claiming that fasting “flushes toxins”. The liver, kidneys, lungs and gastrointestinal system already perform the body’s waste-processing and elimination functions.
Fasting changes metabolism; it is not a magical detoxification procedure.
Is Intermittent Fasting the Same as Ekadashi?
No. They may involve periods without food, but they arise from very different frameworks.
Intermittent fasting is a modern nutritional approach that includes time-restricted eating, alternate-day fasting and other patterns of planned food restriction.
Ekadashi is a religious and spiritual observance rooted in the Hindu lunar calendar, with dietary, ritual and devotional dimensions.
Reducing Ekadashi to “16:8 fasting twice a month” misses its meaning.
At the same time, modern fasting research can help us understand some of the physiological effects that occur during periods of food restriction. The two can inform our understanding of fasting without pretending to be the same thing.
So, What Is the Right Way to Fast?
Perhaps the answer lies somewhere between ancient wisdom and modern evidence.
Start gently: For many healthy adults, a 12-hour overnight fast can be a reasonable beginning. There is no prize for forcing the window to 18 or 20 hours.
Eat well when you eat: A fasting window does not compensate for excessive fried food, sweets, ultra-processed foods or oversized portions.
Protect muscle: Adequate protein and strength-building exercise matter, particularly when weight loss is the objective.
Respect timing: Finishing dinner at a reasonable hour and avoiding habitual late-night eating may be more useful than simply extending the fasting window.
Stay hydrated: Food restriction does not eliminate the body’s need for fluids.
And perhaps most importantly: Do not mistake deprivation for discipline.
Who Should Be Cautious?
Fasting is not appropriate for everyone. Children and adolescents, pregnant or breastfeeding women, people who are underweight or frail, those with a current or previous eating disorder, and people taking glucose-lowering medication may need to avoid fasting or undertake it only with appropriate professional guidance.
Prolonged fasting deserves particular caution and should never be treated as a casual wellness challenge.
The Wisdom Is in the Pause
When I first wondered whether fasting could help with weight management, I was looking for a simple answer. What I found instead was a much more interesting one.
Modern science is giving us new ways to understand fasting: from insulin and glycogen to ketones, circadian rhythms and metabolic adaptation. India’s traditions remind us that restraint, practised with awareness and sensitivity to the individual, can have a place in a healthy life.
Perhaps the wisdom of fasting lies not in going without food for as long as possible, but in knowing when to pause, why we pause, and how to return to nourishment wisely.
