Over the last several years, intermittent fasting has become increasingly popular for its promises of improved health and weight control. For those of you who haven’t heard of this weight loss strategy, it involves alternating between extreme calorie restriction to periods of normal eating. The idea is that if you sharply restrict calories a few days a week or limit eating to a shortened window of time each day then you slow your metabolism and therefore reduce weight and theoretically overall health improves. Some find that it is easier to restrict calories a few days a week than it is to moderately cut calories every meal, every day. But does fasting work? Let’s take a look. First, let’s learn a bit more about intermittent fasting and the risks
involved with this eating pattern.

Types of Fasting Schedules

-Time-restricted eating (the 16/8 or 14/10 method)
In this method you fast for 16 hours of the day and eat a healthy diet for the other eight hours. Or fast for 14 and eat for 10 hours. This method seems to be the most popular as most of us fast while sleeping.

-The twice a week method (5:2 method)
You eat a normal healthy diet five days of the week. The other two days you restrict intake, cutting calories by at least 75% (generally eating 500-600 calories)

-Alternate day fasting
Fast one day (consuming approximately 500 calories ) and resume a regular diet the next

-24 hour fast
Complete fast for 24 hours and then resume the regular diet the next day

Are there side effects or risks?

Side effects of intermittent fasting are numerable. If you’re considering intermittent fasting, make sure to discuss it with your doctor first and be aware of possible side effects which include but are not limited to:

Hunger and cravings
Headaches and lightheadedness
Digestive issues
Irritability and other mood changes
Fatigue and low energy
Bad breath
Sleep disturbances

Intermittent fasting is not safe for everyone. Skipping meals and severely limiting calories can be dangerous for people with certain conditions such as:
People over 65
those still growing (kids, teens)
those with heart, liver, or kidney disease
history of an eating disorder or disordered eating
pregnant or breastfeeding
low blood pressure
taking certain medications
Again, if you’re considering a fasting program (or any diet) always talk to your doctor first.

Does intermittent fasting work?

So far, the studies evaluating intermittent fasting have been relatively short and have enrolled only a limited number of participants. In one, 100 overweight people were assigned to one of three eating plans: restricting daily calorie intake by the same amount every day (similar to a traditional diet plan), fasting on alternate days, and continuing with normal eating habits. At the end of the 12-month study, both diet groups had lost weight compared with the normal eaters.

However, the fasters didn’t fare any better than the conventional calorie cutters. Another study out of The University of California San Francisco found that, compared to people who ate normally, fasters only lost a half-pound more in 12 weeks. The long-term efficacy and safety of time-restricted eating as a weight loss strategy are still uncertain and the long-term effects of weight loss of time-restricted eating as compared with daily calorie restriction alone have not been fully explored.

Bottom Line

Intermittent fasting can be used to facilitate weight loss, however, it is not a guaranteed
outcome. IF for weight loss may have some benefits short term but at this point the long-term
effects of this type of diet are not known. A healthy diet is a balanced diet. Whether you
choose to practice IF or not, eating a wide variety of foods including lean proteins, whole
grains, healthy fats, fruits and vegetables is important. Bottom line is consuming fewer calories
than your body burns is what yields weight loss. To lose weight and keep it off, the best
strategy is to adopt healthy eating and exercise habits that you enjoy so you can stick with
them over time.

Erika Niedernhofer, Registered Dietitian

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