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A Guide to Intermittent Fasting

Elizabeth DeRobertis, Registered Dietitian

December 16, 2019

A Guide to Intermittent Fasting

Are you a breakfast-skipper, or a late-night snacker? Intermittent fasting might be the perfect weight loss plan for you. 

Starting a diet that requires you to make drastic changes or big sacrifices to foods you love is usually a waste of time. People can’t stick to those types of diets over time. The most successful weight loss programs work with your lifestyle, not against it, which is why many people are intrigued by the idea of intermittent fasting. Intermittent fasting is not a diet per se, but a change in the way you eat. Here are the details to help decide if it is right for you.

How does intermittent fasting work?

When you go a long time without eating, your body needs to start burning fat as fuel. Intermittent fasting increases the metabolic rate (calories out) and restricts the food you eat (calories in) – a win-win for weight loss. Say someone was picking up a bagel on their way to work, and snacking too much late in the evening. On an intermittent fasting schedule of 11 a.m. to 7 p.m., the morning bagel is skipped and there’s no opportunity for that late-night piece of pie. Of course you are going to lose weight!
Another benefit is that by not eating, especially carbohydrates, the body is not signaling insulin. Insulin is a hormone that helps the body’s cells open up and store excess food and fat to use as energy later. In overeaters, insulin must work overtime to keep up with the continuous conveyer belt of food, eventually burning out and not working as well. The result is too much sugar left circulating in the bloodstream, which is unhealthy for the heart.

How many hours do you need to go without eating?

Twelve hours is the minimum timespan for successful intermittent fasting. This is the best way to start out. So, if you have breakfast at 8 a.m., do not eat anything after 8 p.m. This will leave your stomach empty from bedtime till the next morning. The next phase would be to try to eat all your daily meals within a 10-hour, and eventually within an 8-hour span – the strictest, and maximum level. Many people stick to 11 a.m. to 7 p.m. or 12 p.m. to 8 p.m. 

In the morning, it is okay to wait to eat until you feel real physical hunger kicking in. Instead of waking up and eating right away, see what time your body starts asking for your first meal (meaning your belly is growling from hunger versus you just thinking about food).

Who should try intermittent fasting… and who should not?

Those who usually eat high-carb, less healthy breakfasts (bagels, French toast, pancakes, cold breakfast cereal, those who aren’t hungry when they wake up, or late-night snackers may do well on this eating plan. Also, some people feel it is overwhelming to make too many food decisions during the day. Since intermittent fasting often involves two meals and one afternoon snack, they have fewer decisions to make and less contact with food during the day, so this plan may make sense for them. 

Who should not try it? Those taking blood-sugar management medication for diabetes should be careful with IF. Also, anyone who needs to take medication with food. People who are prone to migraines or headaches when they go too long without eating should avoid intermittent fasting.

What if you have a special event that throws off your schedule?

Going outside your normal window from time to time doesn’t need to doom to your wellness and weight management goals. Scheduled a morning workout? Just eat a healthy breakfast of two eggs, or Greek yogurt with berries, or a 100-calorie portion of oatmeal with 1 Tbs. almond butter mixed in. (You can drink water or coffee or tea, ideally black or using unsweetened almond milk anytime during intermittent fasting.)

Just remember that what you eat during that meal window DOES matter. I have seen people try intermittent fasting thinking they can eat anything they want, and they do not lose weight. Intermittent fasting is a way to help you to make healthy eating choices, within boundaries.

Elizabeth DeRobertis

Elizabeth DeRobertis is a Registered Dietitian with the Scarsdale Medical Group. To make an appointment, call 914-723-8100.


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