Fasting to Lose Weight: Advantages & Disadvantages

Fasting to lose weight: pros and consFasting involves willingly abstaining from some or all food, drink, or both, for a period of time. Modified fasting methods in which juices, teas and detox diet are consumed are comparatively easier than only water fasting. However, these modified fasts should also be followed for a limited period of time.


  1. Before commencing a healthy diet.
  2. Fast weight loss
  3. To reduce or stop cravings and reduce hunger, breaking the physical aspect of food addiction.
  4. After slipping off healthy eating habits or after Holiday feasting.
  5. As a concrete starting point. Clear starting points are often important for change. It can build into a powerful momentum, which can carry on even after the fasting is over.
  6. Medical conditions: e.g. heart disease, high blood pressure, asthma, arthritis and other auto-immune disorders.


There is great debate among the scientific community about whether fasting has any health benefits or can detoxify the body. However, one topic that most experts agree on: fasting is not a healthy means of achieving fast weight loss. Although the appeal is that fasting achieves quick weight loss – it is quick fluid loss, not substantial fat loss.

Proponent of fasting, Joel Fuhrman MD, author of Eat to Live: The Revolutionary Plan for Fast and Sustained Weight Loss and Fasting and Eating for Health says, “Fasting is not a weight loss tool. Fasting slows your metabolic rate down so your diet from before the fast is even more fattening after you fast”.

Furthermore, fasting for fast weight loss carries additional health risks. Whilst fasting for a day or two is rarely a problem if you are healthy, “it can be quite dangerous if you are not already eating a healthy diet, or if you’ve got liver or kidney problems, any kind of compromised immune system functioning, or are on medication – even Tylenol,” says Dr. Fuhrman.

However, after fasting people often report a positive, healthy change in their diet and lifestyle and thus it can be a springboard in the right direction. Remember for permanent weight loss, you need to adopt a permanent lifestyle change: lowered fat intake, increased intake of unrefined foods (it will fill you up, with minimal calories), decreased consumption of refined foods, drink plenty of water whilst cutting down on other liquids, exercise and get more sleep. Simple and logical! It’s not rocket science. Simply, hard graft, determination and self-discipline!


Fasting to lose weight: pros and consFasting is often used to break the physical aspect of food addiction or a bad cycle of eating. However, it will not necessarily break the emotional ties to addiction. Fasting may stop your body from physiological addiction, but often only disciplined eating can effectively break the deeper emotional addictions by replacing life-long, entrenched, comfort-eating patterns with new healthy ones. You must replace you old damaging habit with a new healthy habit. Commencing a raw food diet and following it for about half the fasting period after fasting will greatly help with any cravings, by allowing an emotional transition from fasting to eating, while still maintaining the need for discipline.


Disadvantages of Fasting for Weight Loss

The problem with fasting is that due to severe calorie restriction, your basal metabolic rate (BMR) will decrease. It is thought that fasting can decrease the body’s metabolism by up to 22%. This means that your metabolism will slow down and theoretically, if you were to eat the same amount of calories you did before you started fasting, immediately on the stopping the fast, you would put on weight – not “water weight”, but fat. If this were to happen, you would end up with a higher body fat percentage than when you started.

Advantages of Fasting for Weight Loss
  • During fasting your stomach tends to shrink, which means you require a smaller food intake to feel “full” and thus naturally decrease your calorie intake once you start eating.
  • After fasting people report to feeling healthier and more energetic and thus are more likely to be more active and burn more calories.
  • To increase your metabolism it is vital that you exercise. If your goal involves weight loss, you must be prepared to adopt a lifestyle change after the fast/ detox, as fasting by itself will not help you to lose weight permanently.
  • If you are fasting for weight loss, avoid water fasting and go for juice fasting or raw foods instead.


Essentially, the bodies starvation response kicks in (like a crash diet ), in order to conserve energy. In the first 24 hours of the fast your body will utilize glycogen (easily-accessible storage form of glucose, stored in small quantities in the liver and muscles) to provide energy for your various body processes to keep functioning. Once your carbohydrate reserves have been exhausted, your body utilizes stored fats. After several days of fasting, your body begins to break down protein, which is converted into glucose. Much of our muscle mass is protein and thus muscle tissue is often lost.


Side effects of fasting may include headaches, weakness, muscle aches, nausea, lightheadedness, irritability, racing heart, exacerbation of joint symptoms, mild abdominal discomfort, and hunger. However, everyone reacts differently to detoxing. While one person may feel energized and revitalized, another may feel sluggish. Generally it is reported that hunger disappear after the first day.

Opponents of fasting, argue that fasting and detox programs can generate a multitude of medical problems that include damage to your gastrointestinal tract, nutrient malabsorption, impaired liver function, anemia, kidney stones and hypoglycemia.


Fasting is not advisable for everyone. Certain people should not fast, including:

  1. Pregnant/ lactating women.
  2. People with wasting diseases or malnutrition.
  3. Those with a history of cardiac arrhythmia.
  4. People with liver or kidney insufficiency.
  5. Children (still growing)

Anyone who fasts for extended periods should do so only under close medical supervision.


Breaking the fast is one of the most important elements of the fast . Although what you do during the fast is of course important, it is what you do afterwards that is critical. In fact, the benefits of a fast depend upon the dietetic management after it is broken. The longer the fast, the more care must be taken in breaking it. Breaking an extended fast can be difficult and can be harder than fasting. A slumbering digestive system is sensitive, and although you might want to try every food on the planet, you cannot because your system needs time to get back to speed.

During the fast, your stomach shrinks and your digestive organs are in a state of inactivity, thus solid food must be re-introduced very slowly to avoid kidney failure or digestive distress.

After a fast, the greatest danger lies in eating too much and too frequently. If you rush into eating solid foods, overloading your digestive organs with large amounts of food, you may provoke acute attacks of indigestion and experience physical problems such as diarrhea, sickness and fainting. Moreover, you risk serious medical disturbances. Before embarking on a fast, speak to your doctor. Also, if you do ignore all the warnings and pursue overeating after breaking your fast, you will pile on weight (fat, not fluid).

After fasting, you should follow a transition phase of re-introducing foods, before returning to eating meat, fats or normal foods. Your organs must be trained to gradually return to normal activity, by introducing very small quantities of light food.

Steps to take after fasting
  1. Increase the percentage of raw food in diet
  2. Eat natural unprocessed food
  3. Eat when hungry
  4. Exercise for mental and physical well being.
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