Weight loss, detox, autophagy: Doctor busts 15 common fasting myths
From weight loss and detox claims to blood sugar control and autophagy hype, an internal medicine expert explains when fasting helps, and when it quietly harms
 "Weight loss, detox, autophagy: Doctor busts 15 common fasting myths")
Fasting has moved from religious practice to wellness trend. Promoted as a shortcut to weight loss, metabolic health, detoxification, and even disease reversal, fasting is often presented as universally beneficial.
For this week’s Fact-Check Friday, Health With BS spoke to Dr Rajeev Chowdry, Yatharth Super Speciality Hospital, Sector 20, Faridabad, to separate fasting facts from fiction, and explain why context matters more than calorie clocks.
1. Does fasting automatically lead to weight loss?
Myth: Fasting guarantees weight loss.
Fact: Weight loss depends on far more than meal timing.
“Fasting alone does not guarantee weight loss,” says Dr Rajeev Chowdry. “Total calorie intake, food quality, metabolic health, sleep, and activity levels matter just as much.”
Many people compensate by overeating or choosing calorie-dense foods during eating windows. Initial weight loss, he explains, is often due to glycogen and water loss, not fat. Stress hormones released during fasting can also trigger rebound overeating.
Sustainable weight loss, Dr Chowdry emphasises, comes from long-term dietary consistency, not fasting alone.
2. Are longer fasts always better for health?
Myth: The longer the fast, the greater the benefit.
Fact: Extreme fasting raises health risks without added gains.
While extended fasts may improve insulin sensitivity in some individuals, Dr Chowdry warns they also increase the risk of nutrient deficiencies, electrolyte imbalance, muscle loss, hormonal disruption, impaired immunity, and fatigue, especially without medical supervision.
“There is no ‘more is better’ approach to fasting,” he says. “The goal should be metabolic balance, not severe deprivation.”
3. Does fasting detox the body?
Myth: Fasting flushes toxins from the body.
Fact: Your organs already do that continuously.
“The liver, kidneys, lungs, and gut detoxify the body efficiently,” explains Dr Chowdry. “Fasting adds no special detox mechanism.”
Extended fasting may even release stored toxins from fat into the bloodstream, increasing strain on detox organs. Hydration, fibre-rich diets, and liver health, he notes, support detoxification far more effectively.
4. Should everyone try intermittent fasting?
Myth: Intermittent fasting suits all bodies.
Fact: It can be harmful for some.
People with diabetes, thyroid disorders, gastrointestinal conditions, pregnancy or breastfeeding, or high chronic stress may experience adverse effects. Even among healthy individuals, responses vary widely.
“Nutrition is individual,” says Dr Chowdry. “Health decisions should not be trend-driven.”
5. Does fasting permanently slow metabolism?
Myth: Fasting ruins metabolism forever.
Fact: Extreme, repeated fasting can impair metabolic flexibility.
Short-term fasting does not permanently damage metabolism. However, repeated cycles of under-eating followed by overeating can reduce metabolic adaptability and lead to muscle loss.
“Under-fueling is the real risk,” Dr Chowdry explains. Adequate protein intake, resistance training, and consistent nourishment protect metabolic health better than extreme fasting.
6. Is hunger during fasting a sign of healing?
Myth: Hunger means your body is repairing itself.
Fact: Hunger is a biological alarm, not a health badge.
Hunger is regulated by hormones like ghrelin and blood sugar levels. Persistent hunger, Dr Chowdry says, often signals insufficient calories, nutrient deficiency, or excessive stress.
“Healing requires fuel,” he adds. “Discomfort does not improve physiology.”
7. Does fasting guarantee better blood sugar control?
Myth: Fasting stabilises blood sugar for everyone.
Fact: It can destabilise glucose levels in some.
In people with insulin resistance or diabetes, fasting may trigger dangerous swings between low and high blood sugar due to stress hormone release.
Balanced meals with adequate protein and fibre, Dr Chowdry notes, often provide better glycaemic stability than prolonged fasting.
8. Is black coffee or supplements during fasting harmless?
Myth: Zero-calorie coffee or supplements don’t matter.
Fact: They still affect hormones and metabolism.
Caffeine can raise cortisol, suppress appetite temporarily, worsen anxiety, disturb sleep, and irritate digestion. Supplements taken on an empty stomach may also interact with medications.
“Not breaking a fast does not equal harmless,” Dr Chowdry says.
9. Does fasting burn fat while preserving muscle?
Myth: Fasting targets fat, not muscle.
Fact: Muscle loss is a real risk.
Without adequate protein and resistance training, the body may break down muscle for energy during prolonged fasting.
“Fat loss with muscle preservation requires nutrition, training, and recovery, not fasting alone,” says Dr Chowdry.
10. Does fasting work because it triggers autophagy in everyone?
Myth: Fasting flips an ‘autophagy switch’.
Fact: Autophagy happens naturally, and varies widely.
Autophagy occurs continuously and is influenced by exercise, sleep, and nutrient cycling. There is no consensus on how long fasting must last to produce meaningful benefits.
“Oversimplifying autophagy ignores biological individuality,” Dr Chowdry explains.
11. Is fasting safe as long as you feel okay?
Myth: Feeling fine means fasting is safe.
Fact: Internal stress may be silent.
Electrolyte imbalance, hormonal disruption, and nutrient deficiencies may not produce immediate symptoms.
“Safety cannot be judged by comfort alone,” Dr Chowdry warns.
12. Did ancient humans fast regularly, and should we?
Myth: Our ancestors fasted, so we should too.
Fact: Context matters.
Food scarcity in ancient times was involuntary and paired with high physical activity and different stressors.
“Evolutionary arguments without context are misleading,” says Dr Chowdry.
13. Can fasting cure lifestyle diseases?
Myth: Fasting can cure diabetes or heart disease.
Fact: It is a tool, not a cure.
Fasting may improve short-term markers, but long-term disease management requires diet, exercise, stress reduction, medication adherence, and medical follow-up.
Relying solely on fasting, Dr Chowdry cautions, can delay essential treatment.
14. Do women benefit from fasting the same way as men?
Myth: Fasting affects men and women equally.
Fact: Hormones change the equation.
Women may experience menstrual irregularities, thyroid disruption, fertility issues, or mood changes due to caloric restriction.
“Gender-specific physiology must be considered,” Dr Chowdry says.
15. Is skipping meals the same as mindful fasting?
Myth: Skipping meals equals fasting.
Fact: Intent matters.
Mindful fasting involves planning, nutrition, and hydration. Unstructured meal skipping, often driven by stress, can disrupt hunger cues and metabolic regulation.
According to Dr Chowdry, fasting is neither a miracle cure nor a metabolic villain. Its impact depends on who is fasting, how, why, and for how long.
“Health is built through consistency, balance, and individualisation,” Dr Chowdry emphasises. “No single dietary method works for everyone.” About Fact-Check Friday
Misinformation in health can be more harmful than the illness itself. That’s why every Friday, Business Standard brings you Fact-Check Friday, a weekly series where we unpack myths, wellness trends, and separate evidence-based medical insights from popular misconceptions. From ageing and mental health to fitness, diets, and everyday remedies, our fact-checks are guided by doctors, researchers, and public health experts, so you can make informed choices for your well-being. Explore more fact checks here:
This content is for informational purposes only and is not a substitute for professional medical advice.