Take It In: by Carol Bareuther
Fasting — the simple process of going without food for several hours or days — is a practice as old as mankind. In fact, our bodies were built to live the feast-and-famine lifestyle of hunter-gatherers or we wouldn’t be here today.
Fasting is also a part of many religions such as going without food or water in daylight hours during Ramadan.
Just because we can survive without food for a short time, does this practice help us to thrive? Some studies say yes.
There are several types of fasts. Each has its own dietary restrictions and health effects.
Time-restricted feeding is when food is eaten only at certain times of the day. For example, a period of 12-hours per day without food fits this definition. It’s mainly used as a weight-loss plan, with success depending on how much a person eats during the remaining 12 hours of the day.
Alternate-day or intermittent fasting is popular today. It involves eating very little on some days of the week and “normally” the rest. An example is the 5:2 diet. On this, a person eats only 500 calories (for women) or 600 calories (for men) a day for two days a week. Another variation of this is the 4:3 fast, which is fasting every other day.
Some studies show that intermittent fasting can increase the growth of new nerve cells and boost brain function as well as protect against brain damage that can lead to stroke.
Short-term and prolonged fasting happens when no food is consumed for consecutive days. This is typically less than three days in short-term fasting and more than three days in the prolonged form. Results of a 2014 study by University of Southern California researcher Valter Longo on mice that were made to fast from two to four days at a time revealed that this eating (or non-eating) style caused the immune system to reboot or regenerate with new immune cells while discarding the old ones. Thus, this could be cancer protective.
Since then, Longo has developed his Periodic Fasting Mimicking Diet. This low-calorie eating plan – from 725 to nearly 1,100 calories per day — is followed for five days each month, while eating “normally” the rest of the time. Research shows that this can help the body age more slowly and thus slow the health problems associated with aging.
The catch? The foods must to be purchased from Longo’s company or an approved health care provider. It all comes in little bags. Examples are a Vegetable Soup Blend, and Kale Crackers and Olives.
Beyond these, there’s the celebrity-powered popularity of juice fasting. This calls for swapping solid food for fresh juices. One of the most popular of these is the Master Cleanse, where the recommended libation is a heady mix of lemon juice, maple syrup and cayenne pepper.
There is little research on the benefits of juice fasting. On one hand, getting plenty of fruits and vegetables, even in juice form, provides several disease-preventing nutrients. On the other hand, throwing out all the fiber is counterproductive. The dietary fiber offers its own benefits and adds to a feeling of fullness not easily achieved on liquids only.
There’s another point to consider in fasting. That is, eating less and losing weight can provide health pluses of its own. For example, according to the U.S. Centers for Disease Control, losing as little as 5 to 10 percent of body weight for those who are overweight can improve blood pressure, blood sugar and blood cholesterol levels. This isn’t much. For instance, if you weigh 200 pounds, a 5 percent weight loss equals 10 pounds or a weight of 190 pounds.
Lastly, going for long periods of time without eating can be unhealthy. The risk of dehydration is increased. Plus, for those on medication such as drugs to lower blood sugar or pressure, the negative effects of fasting can be life-threatening.
Busy yacht crew may want to consider carefully the timing of any fast. My recommendation as a registered dietitian is not to try it when on duty or on call. This is especially so for those who have never tried fasting before and don’t know how they might react. A steep drop in calories can cause some to simply be cranky (and passing that off on guests and fellow crew) or to feel faint or even passing out.
Carol Bareuther is a registered dietitian and freelance health and nutrition writer. Comments are welcome below.