Many people, especially hard-core fitness types (ahem), fear if they don’t get some nutrition every 3-5 hours then they will lose muscle and kill their metabolisms. Actually the opposite is true, according to Mark Sisson (the man with all the answers). “It all makes sense from an evolutionary perspective, because our predecessors almost certainly went through regular cycles where food was either abundant or very scarce. The body may have established protective mechanisms to adapt to these conditions by sensitizing insulin receptors when it was critical that every bit of food be efficiently used or stored (as in famine), or by desensitizing them when there was a surplus, so the body wouldn’t be overly-burdened by grossly excessive calorie intake.”
Food is great. It’s delicious (usually) and fun to eat and everyone, everywhere needs to eat it. Going against this primal urge is difficult, especially at first. While there are, of course, reasons why some should not attempt fasting (if you are struggling with an eating disorder, for instance, or diabetic or hypoglycemic) for most of us it can be an awesome experience on many levels.
To try it, pick a day when you don’t have a lot going on (the day of your big presentation or your final exam is probably not the best time to start this) – I usually choose my rest day so I don’t have to worry about dying of thirst after a run – and just plan to skip a meal*. Then try skipping two. The type of fast you do – juice, water only, 18 hours, full abstinence – is up to you. There are as many types as there are people. Just take careful note of how it makes you feel and what, if any, differences you notice. Fasting may be the cheapest and simplest health “products” out there! (Note I did not say “easiest”.)
Caveat: When people discover that I fast, they generally say “Oh, you must lose so much weight!” This would not be true. Both Krista and I have noticed that fasting does not cause either of us to lose weight. While the research shows that fasting, over a long period of time, can help you maintain a healthy weight, it doesn’t work like a crash diet dropping 10 pounds in 10 days.
Have any of you fasted before? What kind did you do and how did it make you feel? Do any of you have religious practices that affect your workout?
*Be smart. Check with your doctor first if you have any health concerns. I am not a doctor, a nurse, a guru of anything or even all that smart sometimes (as evidenced by my massive collection of ridiculous footwear). If you start to feel sick, stop immediately.