Weight lower but more cranky with fasting

February 2, 2005 in Nutrition Topics in the News

Weight lower but more cranky with fasting

Fasting every other day may be a possible way to slash calories -- if you and those around you don't mind the crankiness that comes with it, according to researchers.

Their study of 16 nonobese men and women looked at the effects of alternate-day fasting, an eating plan that interspersed fasting days with "feasting" days that allowed participants to eat as much as they wanted. The researchers were interested in finding out if food deprivation every second day would be easier on people than counting calories on a daily basis.

They found that the diet plan was indeed "feasible," at least for the duration of the 3-week study. Overall, the men and women lost an average of 5 pounds, while shedding some body fat.

On the other hand, researchers said a major problem existed - this being the crankiness that erupted on the fasting days and did not abate over the 3 weeks.

Uncovering the most tolerable ways for people to cut calories is not just a matter of trimming waistlines. A number of studies have now shown that calorie restriction can extend the lives of animals.

There are a number of theories on why restricting food intake might make for a longer, healthier life. One idea is that slowing the rate of metabolism reduces the generation of oxygen free radicals, potentially cell-damaging molecules that are a normal byproduct of the metabolic process.

It remains unknown if calorie counting can extend human life as it does for some animals. Researchers are currently conducting a trial, sponsored by the National Institutes of Health, which is examining how long-term dietary restriction affects people's health and longevity.

Studying dietary restriction in people is very complicated. The ongoing trial is investigating how calorie cutting affects "biomarkers of longevity" in people, such as levels of blood sugar and insulin, a hormone key in regulating blood sugar.

The trial is testing several methods of dietary restriction -- from pure calorie cutting to burning extra calories through exercise -- to see which are most viable.

In the current study, researchers evaluated the effects of alternate-day fasting, an approach not included in that trial. They wanted to see if the eating plan was feasible and whether it influenced biomarkers of longevity, as well as participants' weight and metabolism.

According to Ravussin, participants were not able to "make up" for what they didn't eat on fasting days, and consequently, they generally lost a few pounds and some fat mass. However, the researchers also found that many participants said they were irritable on food-free days, and they did not appear to get used to having an empty stomach every other day.

All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.