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What is intermittent fasting (IF) and how can it help you lose weight?


By Jennifer Kyser, RD, CSWOM, LD

Intermittent fasting or time restricted eating is an eating pattern that involves periods of fasting and eating. You do this daily and not even realize it. When you are sleeping you are fasting and when you are awake you are eating. For example, assuming you sleep 6-8 hours at night and have your first meal at 8AM, you may eat 2 other meals and maybe some snacks and stop eating around 10PM. This pattern will have you fasting 10 hours and eating in a 14 hour window. To help you lose weight it is better to fast longer and to have a shorter eating window. This can be easily done by not eating a few hours before bed and wait a few hours to eat after you get up. So how can this help you lose weight?


Obesity is a chronic disease caused by many factors, it is not simply caused by eating too many calories. Obesity is more of a hormonal issue, this hormone is insulin. Insulin is a storage hormone, intake of food leads to insulin release and insulin turns on storage of fat and sugar. When you are not eating, insulin levels will fall and then your body will burn sugar or fat. To help you lose weight it is best to focus on reducing insulin levels. Reducing insulin will mostly depend on what you are eating and when you are eating. In short, high levels of insulin= fat storage and low levels of insulin=fat burning.


If you are have followed any diets in the past you know most diets are focused on what and how much you should be eating and there is very little focus on how often or when you are eating. I am sure you have heard to eat 6 small meals daily because this will increase your metabolism, this is a myth. The more frequently you eat the more insulin is released which will prevent you from burning fat. Remember, high levels of insulin will prevent you from burning fat no matter how many calories you are eating. It is said often that eating breakfast is the most important meal of the day because it will “get your metabolism going”, this is a myth as well. Your insulin levels are typically lower in the mornings because you have gone all night without eating, this is a good time to extend your fasting to help you burn fat. Ideally, consolidate your meals and eat as few meals as possible and avoid snacking if at all possible.


Longer periods of fasting = lower insulin levels. A great way to achieve these lower levels of insulin is practicing intermittent fasting. This can be done in many ways, you can fast daily which would include fasting overnight and having a defined window of eating during the day. Your schedule could be 12/12 (12 hours fasting/12 hours eating), 14/10 (14 hours fasting/10 hours eating, 16/8, 18/6. You can also do a 5/2 fast which involves fasting 2 non-consecutive days per week and eating normally the other 5 days. It is important to choose a schedule that works for your lifestyle because you will be more likely to stick to this schedule. If you typically eat dinner with your family at 8PM you would not choose a fast that starts at 6PM. There is no one IF schedule that is best, to see the best results the important thing is being consistent. The longer you practice IF the more effective it is for you and it becomes a lifestyle, not a diet. If the thought of fasting 16 hours is overwhelming, start with a smaller fasting window and increase your fasting time gradually.


It is important to drink fluids while you are fasting especially if you are doing longer periods of fasting. You must avoid anything with sugar as this will break the fast .You can have fluids such as water (can use lemon or lime), unsweetened tea, black coffee, flavored waters, flavored sparking waters or broth. You may use artificial sweeteners, ideally stevia or monk fruit is best. You may add a small amount of half and half or heavy whipping cream to your coffee if desired, avoid any flavored creamers. Avoid alcohol. Diet soft drinks would be ok in small amounts.


There are many benefits to fasting including; less meal planning, no calorie counting, less time to think about food, improved hydration (as most people will drink more because they are fasting), clearer mind, gut rest, improved insulin sensitivity, improved energy to name a few. ZERO app is a timer that you can use to help you keep track of your fasting schedule. If you would like to learn more about fasting I would suggest reading The Complete Guide to Fasting by Jason Fung, MD with Jimmy Moore.


Disclaimer: Most individuals can practice intermittent fasting but it is not appropriate for children and pregnant women. If you are diabetic and taking medication please check with your doctor before starting this.


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