Fasting: Does it Improve Health & Help Manage Weight?
Fasting is a process that involves restricting food intake for a given period of time and it’s a practice that has been done for thousands of years. Most fasts are for religious or social reasons, but now many headlines have been promoting the restriction of food for health-related reasons too. Anyone who has fasted before knows that swearing off food for long periods of time means dealing with constant hunger and fatigue. So it’s important that anyone who chooses to try fasting know the real effects that come with it.
Different types of Fasts
Traditional Fasting: Traditional fasting usually restricting food for multiple days at a time or longer, but still drinking water.
Intermittent Fasting: Intermittent Fasting involves the practice of going without food for small stretches of time to sometimes as long as a day, before shortly resuming normal food intake again.
Reduced Intake Fasts: This type of fast involves consuming only a very small amount of calories each day (usually 300 calories or less) for multiple days.
Today, many people are looking to try fasting both as a health promotion strategy and a weight loss strategy. Studies too are actively trying to figure exactly what effect fasting has on the body and what type is best. The results found so far have been mixed, but do show that this is a practice some people may find benefits through.
Specifically, studies have shown that Traditional Fasts (also sometimes called total caloric restriction) reduce inflammation levels in the body and may help slightly slow the aging process (1). Other studies have found that reducing inflammation is a normal process which happens with Reduced Intake Fasting too, even when calories are just largely reduced (2).
Muslims who practice Ramadan (a common religious holiday with intermittent fasting) will often say that completing their fasts bring a new energy and are key to good overall health. The process though can involve initial hunger, daily fatigue and mental fogginess. Other faith groups will also praise fasting as a beneficial process and vital to renewing of the body and spirit. So there is a lot of admiration for fasting in terms of a how a person feels and there may even be some science behind these feelings, but it’s rough and it’s not yet proven however that this leads to longterm benefits for a person.
The other popular reason some are trying a fast is for weight loss. Of the types, intermittent fasting has been in headlines as the latest new strategy to shed body fat. As one would expect, restricting food does naturally lead to weight loss, but may not be sustainable for everyone. In a study of men strength training and practicing Intermittent Fasting 16 hours each day for 8 weeks, men who fasted did lose slightly more body fat than those who followed a traditional reduced calorie eating plan (3). However, it was found that fasting also reduced the men’s testosterone level compared to the control group.
Other studies looking at fasting and weight loss results show beneficial hormonal changes like improved insulin sensitivity and favorable changes in leptin and adiponectin (hormones that regulate hunger and weight). So there may be some small helping hand that completing a fast contributes to one’s overall metabolism. Overall, most health experts agree on one central thing which is that eating patterns that constantly vary in timing and frequency are not conducive to good health or long term weight loss (4). In other words, frequently switching eating habits can be hard on the body, being consistent in a healthy diet is still the best approach.
The important thing to remember is that fasting is a tough practice to follow and while it does yield some benefits, it shouldn’t be (and often can’t be) a strategy followed forever. Nevertheless, fasting can be a refreshing strategy to try for anyone curious about the benefits it may bring about in overall health.
- Zhang, Nannan, et al. “Calorie restriction-induced SIRT6 activation delays aging by suppressing NF-κB signaling.” Cell Cycle 15.7 (2016): 1009-1018.
- Lettieri-Barbato, Daniele, Esmeralda Giovannetti, and Katia Aquilano. “Effects of dietary restriction on adipose mass and biomarkers of healthy aging in human.” Aging 8.12 (2016).
- Moro, Tatiana, et al. “Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males.” Journal of Translational Medicine 14.1 (2016): 290.
- St-Onge, Marie-Pierre, et al. “Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention: A Scientific