The Unknown Dangers of Extreme Diets!
By Dr. Malavika Athavale +2 more
Medically reviewed by Dr. Malavika Athavale
Last updated: Feb 12, 2026 Published on: Oct 1, 2018
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By Dr. Malavika Athavale +2 more
Table of Contents
The current societal environment is marked by a changing perception of beauty, which can largely be attributed to advertising and media portrayals of an ‘ideal’ body type. This often pressurises vulnerable young people to fit into a ‘society-approved’ mould.
Losing weight and attaining an ideal body type feature prominently on most people’s to-do lists, whether as a New Year’s resolution or while planning for a big event or holidays. While maintaining a healthy weight is important for long-term health, the diet industry thrives on people’s desire for rapid weight loss, often promoting quick results over healthier approaches.
What we fail to realise is that extreme diets can pose many health risks. There are no true shortcuts to healthy weight loss, which is best achieved through a balanced diet, regular physical activity, and healthy lifestyle habits1.
In the quest to lose weight quickly and easily, most people tend to go on an extreme diet. This usually involves reducing their calorie intake substantially to lose a lot of weight in a short period, which essentially pushes the body beyond its healthy limits.
As a general guide, men typically need around 2500 calories a day and women about 2000 calories a day, depending on their age and activity levels. Individuals with obesity may be recommended a calorie-controlled diet to achieve a healthy weight, but this should be ideally planned under a doctor’s or dietitian’s supervision. Many dietitians advise gradual weight loss of about one or two pounds a week. Losing weight faster than this through dieting is generally considered extreme dieting2.
While extreme dieting may have the desired effect of rapid weight loss, it is often associated with many potential health risks due to severe calorie restriction and limited food variety. Extreme dieting may not be sustainable as it may lead to an increased risk of disordered eating behaviours like binge eating and an unhealthy relationship with food. If you are considering an extreme diet, you should ensure that you have a full understanding of the possible health risks and side effects of reducing calorie intake and restricting your food choices3.
In my experience and research, I advise against extreme dieting, especially for young individuals. In a study, it was found that self-led extreme dieting actually led to more weight gain over time. Instead, focus on adopting balanced and healthy eating habits to maintain a healthy weight in the long term.
Dr. Rajeev Singh, BAMS
Extreme diets yield extreme results but not always in the way you would like. They are more likely to make you feel fatigued, moody, nauseous, or irritable. They may also lead to electrolyte imbalance, reduced immunity, hair loss, and digestive issues like bloating and constipation4,6. In the long term, they can set you up for metabolism problems, rebound weight gain and life-threatening medical conditions. The following is a breakdown of the changes that happen in your body when you follow extreme diets like completely eliminating carbohydrates, following a liquid-only diet, or severely calorie-restricted diet.
The immediate ‘success’ of a crash diet is just an illusion, as any pounds that are lost most likely come from water rather than body fat. When on a restricted-calorie or carbohydrate intake, the first source of energy the body burns, long before fat, is glycogen. Glycogen, a form of carbohydrate stored in the liver and muscles, is bound to water, so its depletion leads to significant fluid loss. As a result, dehydration may occur, with symptoms like headache, fatigue, and dizziness7.
Since extreme diets may be associated with yo-yoing or gaining back all of the weight that was lost on a diet, they may contribute to insulin resistance and potentially type 2 diabetes8.
Malnutrition and extreme diets are deeply connected. Malnutrition can lead to the atrophy of muscles throughout the body, leading to muscle wasting. If weight loss is extremely fast, the muscles of the heart can atrophy. Extremely low-calorie liquid diets, for instance, have been linked to ventricular arrhythmias and death. A weakened heart is a serious problem that can be life-threatening2,9.
When one is following extreme diets, the body experiences a calorie deficit and energy levels drop, metabolism will naturally slow to conserve energy. This can stall weight loss and lead to the loss of muscle tone
In the case of extreme diets, severe diet restriction leads to many nutrient deficiencies such as carbohydrates, proteins, vitamins (especially vitamins A, D, E, and K) and minerals like calcium, phosphorus, and sodium. These are essential food groups, and their deficiency can cause numerous health conditions10.
Losing weight very quickly, especially by following extremely low-calorie diets, may lead to the release of more cholesterol into the bile and incomplete emptying of the gallbladder, both of which can increase the chances of developing gallstones11.
Severe reduction in calorie intake may affect the function of key hormones such as leptin, thyroid hormone (triiodothyronine or T3), testosterone, and oestrogen (estradiol), which are involved in appetite control, metabolism, and reproductive health. This may contribute to symptoms such as irregular periods, reduced fertility, low energy levels, and changes in mood5.
Severely restricted and long-term dieting or rapid weight loss can disturb the body’s natural hormone balance, which plays an important role in regulating the menstrual cycle. This makes the body reduce the hormone production needed for regular periods. As a result, menstrual cycles may become irregular, delayed, or stop completely for some time, leading to the absence of periods (amenorrhoea)5,12.
Following a restricted diet for a long timemay reduce the availability of calcium and vitamin D in the body, potentially leading to weakened bones and increasing fracture risk13.
According to research published in The Journal of Neuroscience, extreme diets or crash diets, even if they contain an adequate supply of carbohydrates, increase the levels of the stress hormone corticosterone in the brain, making it more susceptible to stress, increasing the risk of depression and potentially increasing the risk of future binge-eating behaviours14.
Based on what I’ve seen in adults, chronic dieting can lead to various symptoms such as constantly thinking about food, feeling easily distracted and irritable, experiencing fatigue, and having a tendency to overeat or even binge eat. The mechanism behind this is that restrictive dieting can put the body in a state of deprivation, leading to increased cravings and a heightened focus on food.
Dr. Siddharth Gupta, B.A.M.S, M.D (Ayu)
If you have been fasting for a long time or are on a low-calorie diet and experience the following symptoms, you should consult a doctor at the earliest:
While extreme diets may seem tempting because they promise fast results, they often place unnecessary stress on the body and can be difficult to sustain. In contrast, choosing a healthy approach to weight loss supports the body’s natural processes and reduces the risk of side effects such as weakness, nutrient deficiencies, and hormonal imbalance. A steady, well-planned approach seems to be the best way to lose weight as it helps the body adapt safely to changes in diet and activity.
Healthy weight loss focuses on balanced meals, regular physical activity, and realistic goals that fit into everyday life. This method helps preserve muscle, maintain energy levels, and support overall physical and mental wellbeing. Although progress may be slower, healthy weight loss is more sustainable and increases the chances of maintaining results in the long term.
Extreme diets may lead to quick weight loss, but they often place significant strain on the body and increase the risk of both short- and long-term health problems. A healthier approach that focuses on balanced nutrition, regular physical activity, and gradual weight loss is safer and more sustainable in the long term. If you are concerned about your weight or eating habits or need advice on how to safely diet and lose weight, seek guidance from a dietitian or doctor.
Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information and disclaims any liability arising thereof.
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