Fixin’ to Fast? by Jean Jitomir

I recently received the following set of questions from a reporter; she seemed to think that fasting is a swell idea for college-aged people.  Her leading inquires seemed to ask for support for a meal plan that does not involve food.  Unfortunately, many college students take this counter-productive approach when quickly trying to drop several pounds for spring break, a formal, or other event. Names have been removed to protect the guilty.
Hello Jean,
My name is Xxxxxx Xxxx and I am a staff writer for The Xxxxx. I am writing an article regarding fasting, and I was hoping you could answer some questions.
1. What happens to the body when someone fasts?
During a true fast, no energy (Calories) enter the body.  However, the body needs a certain amount of energy to function and cannot burn only fat to meet these energy needs; the brain, kidney, and other organs need a certain amount of sugar to function.  During the first several, the body will rely on the breakdown of limited carbohydrate stores (glycogen) in the liver to meet sugar requirements.  However, after liver glycogen is exhausted, the body will destroy muscles to make sugar.  YOU CANNOT MAKE SUGAR FROM FAT.  There’s a little molecule that holds fat in place that make a tiny amount of sugar, but the fatty acid itself cannot be converted into sugar. Never, No, Nada.  During a fast, working muscles rely on muscle glycogen and protein breakdown (yes, fasting turns your muscles into little cannibals), and fat oxidation.
Glycogen is used up completely within a day, and for the remainder of the fast, the body will use exclusively protein and fat to make energy.  Fasting is very complex and the body will break down more body fat or muscle depending on how long one fasts.  
Muscle Breakdown: Muscle is eaten up to provide sugar at a much faster rate during the beginning of a fast.  The body still needs a lot of sugar to feed the muscles because it is not “used to” using other fuels yet.  As a result, a short fast burn a whole lot of muscle mass.  Muscle protein breaks down to its little parts, which are the amino acids (AA).  Some AA can be used to make sugar and some make products that are more like fat.
Fat Breakdown: Fat can be used for energy in some areas of the body, like the muscle; however, the organs cannot use regular-strength fat for energy.  As a person continues to fast, the body gets scared because it is loosing a lot of muscle to feed the organs.  As a result, it starts to spare some muscle by turning the fat in to ketones.  Organs, like the brain and kidneys, “learn” to use ketones and use less sugar as a result.  The brain will ALWAYS need some sugar, however, so a person will ALWAYS be breaking down muscle if she does not eat!
After several days of fasting, like in the case of a hunger strike, the body will do several things to protect itself and extend life: 1) slow metabolism; certain “non-essential” functions will be sacrificed as a result, including, but not limited to: sexual desire/menstrual function, immunity to diseases, hair and skin renewal, and thyroid hormone production; 2) the body slows the rate muscle breakdown.  You will die once you loose a certain percentage of your muscle mass (there are calculations for this!).  Your body is trying to allow to live in a starving state for as long as possible; and 3) the body will also use more fat, both to burn fat itself and to make ketones to feed the organs. 

2. What are the benefits of fasting?
Some individuals consider fasting important for religious purposes.  If there is not a spiritual reason for fasting, I would never recommend it.  I am a dietitian and never fast, unless very ill.
Some research shows benefits for individuals following a prolonged low-energy diet, but after a prolonged fast, all the evidence shows that it predictably leads to death.

3. If you decide to fast, are there any specific things someone should do?
If one chooses to fast for religious reasons, try to consume some liquid energy, if that would still allow one to be compliant with the religious guidelines.  Even a small amount of sugar or amino acids (100-150g/day, providing about 600 kcal in energy) in a liquid during a fast will help to preserve muscle mass.  Furthermore, I would recommend ample water and a multivitamin.

4. How often do you recommend fasting?
Never, as stated above.  If your goal is to loose weight, there are better and more effective ways of going about it.  Fasting quickly gives the body signals that it is starving-- this will result in a dramatic reduction of calorie-burning. For weight loss, I would recommend: 1) eating 5-6 small snack-type "meals" per day; 2) eating lean proteins during least three meals.  Lean protein sources include chicken breast, tuna, 95% lean ground beef, top round steak, egg whites, whey and soy protein powders, to name a few; 3) Base all of your meals on fruits and vegetables; 4) Limit all processed foods.  For instance, if it is shelf-stable and sealed in a wrapper, it will not be helpful for your long-term weight loss efforts.

5. What happens if you binge eat after fasting?
There are some potential benefits to eating more healthy foods after a fast.  You will stimulate your metabolism, provide needed nutrients to your body, and increase circulation of the hormones that tell your body you are NOT starving anymore (e.g. leptin).  On the other hand, you may get used to eating too much and store a good amount of the extra food as fat.  A “binge” of high-energy, low-nutrition foods (junk food) will amplify the fat storage.

6. Is fasting recommended at all for college students? How would students specifically benefit?
Students need food to fuel their brains and bodies and should focus on eating regularly spaced meals that have vegetables, lean protein, and whole grains.
Clearly I’m not a fan of fasting.  If you want to loose weight for an event, please do your body a favor and give yourself at least 5 weeks to loose 10 pounds (2 lb per week).  Exercise more, eat better, and you will be able to sustain your weight loss for long after your trip!

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