Finding the right nutrition plan can be a win to improve your mood, your energy levels and many facets of your health. Intermittent fasting is a tool that many individuals are finding to be a winning strategy. If you are considering trying an intermittent fasting schedule, find out more about its benefits and who it might be especially great for in this Intermittent Fasting 101 Guide.
Many of us may think of fasting as a strict limit on food and/or drink related to holiday rituals, weight loss, or “gut cleanses”. These examples often involve many days of limitation that result in intense responses in our body. There are ways to fast without it being so intense that can have positive effects on health. In fact, intermittent fasting can be a way of helping us manage blood sugars, improve our sleep and boost the immune system. While we’ve chatted before about intermittent fasting for athletes in this post, today we’re going to dive into this topic a bit further for the general public.
What is Intermittent Fasting?
Intermittent fasting (IF) is an eating pattern that relies on limiting the times during which one eats as opposed to limiting the amount that one eats. There are many different versions of this style of diet which you can read more about here. Consider these along with your diet goals if you are looking to try IF; one style may work better with your natural eating patterns or your work/home schedule.
- Complete alternate day fasting utilizes one day of normal food intake followed by one day of no food intake.
- 5:2 Regimen has normal eating for 5 days with 2 days (up to 48 hours) of fasting
- Time restricted feeding, or circadian rhythm fasting, limits food consumption to a period of 4 to 8 hours every day.
There are variations on each method and others not listed here, but these are the general structures that have been utilized in the studies that we talk about in this post.
What are the benefits of fasting?
The switch to ketone utilization and change in hunger signals that result from IF can aid with managing blood sugars, improving sleep and supporting the immune system. This fasting schedule can be an alternative to food restriction. Depending on the type of food eaten with the fasting schedule, it can shorten periods of high blood glucose levels or eliminate them altogether. With these short fasts, the type of fuel used by many cells in your body changes as well, so not as much glucose is needed for energy. Besides being better for our cells, it can make losing weight easier, minimize food cravings and improve food choices. Curious how IF can do all of this? Keep reading!
What happens in our bodies during IF?
When we fast, we rely on our body’s own energy stores: fat. As we pull from this reserve, our liver starts producing a fuel source called ketones, which is usable by almost all of the cells in our body. Ketones do not impact blood sugar levels and also do not have many of the same consequences that high blood glucose levels can. To some degree, relying more on ketones for energy may be healthier.
During fasts, we may initially feel hungry, but that is simply a signal from our stomach saying, “Hey! I’m empty!” As the fast continues and ketones start to fuel our cells, that signal is replaced by different signals that tell our brain we have a fuel supply available. The more that we stick to a routine with our eating habits, the more our brain’s signals become regular as well. It may seem counter-intuitive, but as we get used to an IF schedule, our bodies start to expect food only during certain hours and we have fewer feelings of hunger outside those hours.
How does IF help manage blood glucose levels?
Maintaining a healthy weight and healthy blood markers is a struggle for many of us. When we consume food, the different nutrients enter our blood and circulate to our cells to provide fuel. Having a sufficient supply of this fuel is important but having too much in the blood can cause stress on certain organs, especially the pancreas, liver and heart. The pancreas and liver both help to supply and regulate the right fuel for all our different cells. When they have more fuel to manage from the diet, they work harder. Over time, this hard work can cause wear and tear on these organs and they may start to fail. This is one cause of Diabetes – damage or failure of the pancreatic cells. Our pancreas is especially important in managing a fuel called glucose that comes from carbohydrates in our diet.
Blood glucose levels, often referred to as blood sugar, are a common marker of how well our cells are using and storing this fuel. When high amounts of glucose stay in the blood, rather than enter the cells, it can affect how much oxygen our blood carries from the lungs. Sometimes this means the heart works harder to get oxygen to all the tissues in the body. High blood glucose can also prevent our cells from having protection against unwanted entry of invaders and toxins. When there is too much glucose in the blood, it also causes an increase in fat storage and which usually goes alongside weight gain. All of these are downsides to having too much glucose in the blood and can lead to more complicated diseases including diabetes, hypertension and heart disease.
Blood glucose levels are impacted most by carbohydrates in foods: breads, grains, fruits and added sugars. There are a few different popular diets that help manage carbohydrate intake including low carb and ketogenic. If you are curious about these diets, take a look at our previous post to see if they might be right for you. For many, these restrictions can be challenging! IF can support utilization of ketones and serve as an alternative to restricting foods. Any of the IF schedules mentioned have evidence supporting their benefits in helping to maintain steady blood glucose levels in different individuals.
How does IF supporting Immune System?
When blood glucose levels are high on a regular basis, there is an increase in inflammation in cells, tissues and organs across the body. Inflammation refers to a part of the immune system that helps to protect us from invaders and toxins. When alot inflammation is present, these same protective forces start to work against our cells and immune system and damage our own tissues. It is important than we eat nutrients (antioxidants) and maintain a diet that helps to manage inflammation.
Not only does IF help with keeping blood glucose levels more steady, it also produces ketones that can help to reduce inflammation! Ketones (beta-hydroxybutyrate) seem to help with turning off some of the cells’ inflammatory response and with calming the immune system. This is especially helpful for those who already have inflammatory diseases and who are sensitive to allergies. There are even studies starting to look at the benefits of IF for those with Type II Diabetes. While all of the methods of IF seem to help lessen inflammation, longer fasts have greater benefit; the 5:2 method may be the best to choose if this is the top reason you are considering IF.
How does IF Improve Sleep?
Maintaining more steady blood glucose levels during fasting can also help with maintaining mental focus during waking hours. Limiting the ups and downs in blood sugar can also mean we can settle into a deeper sleep at night. Following an eating schedule also helps keep the hormones that control sleep. In addition, it can help us stick to a routine which is especially good for the hormones and signals that control our daily activities. The circadian rhythm method of IF may be most recommended if this is your main focus.
Who should not consider fasting?
Despite the varied benefits of IF, it may not be a healthy option for certain individuals. More information about this is shared in a previous post. The Academy of Nutrition and Dietetics does not recommend energy restriction in children and pregnant or breastfeeding mothers so it does not interfere with growth and development needs. Elderly, individuals with an eating disorders and individuals with body dysmorphic disorders should also be cautious with starting a fasting schedule. These populations may struggle with nutrient deficiencies or hypoglycemia and not enough evidence is available to demonstrate a benefit for these groups.
What can I eat while Fasting?
IF mainly refers to the eating schedule; however, some foods may be helpful with fasts to help reduce hunger, maintain feelings of fullness, and provide adequate vitamins and minerals. While it is not necessary to reduce carbohydrates to gain the effects of IF, eating your carbs toward the middle of your eating window can help to prolong the effects of the fast. For example, breaking your fast with an egg and vegetable omelet or frittata instead of a bagel means your blood glucose levels will stay lower longer. Also, including vegetables with your snacks and meals is also a great way to ensure that you are consuming adequate vitamins and minerals. Here are is a mushroom bruschetta, beet salad and a vegan coleslaw that are tasty choices.
Consuming healthy fats (avocado, vegetable oils, nuts and seeds) can help with feeling full and also help maintain the production of ketones. Many of these fats, especially Omega 3 fatty acids found in nuts, seeds and fish, also seem to also help in reducing inflammation. So many great reasons to make these fats part of your daily intake! Try consuming nut and seed bars or spiced nut mix as snacks, adding some cheese to your omelet or mixing some healthy oil into your veggie dishes. This link has some additional yummy snack options including avocados. And for a sweeter treat, try these almond butter protein bars.
One other eating strategy with IF is having smaller meals and snacks more frequently during your eating window. Maintaining a lower glycemic index, with smaller meals and higher fiber content, will have a smaller impact on blood sugar levels than fewer larger meals will. There are lots of great suggestions for salads, snacks and lighter meals in the recipe section of this site.
Where do I begin with IF?
Any time that you change diets, it is ideal to consult with a Registered Dietitian (RDN) for help with your bodies specific needs and to ensure you are getting all your proper nutrients. The first steps will be to record your current eating habits and schedule and decide what type of IF and what timeline works best for your body and your habits. Then you can discuss any modifications to foods to ensure you are getting all your calories during your eating window.
It will take your body anywhere from a few days to a week to fully adjust to the new routine, so be patient. Try to stick with your plan for at least a week before considering changes. Make small changes and only one or two at a time until you can find the right foods and schedule that feel great. If one version of IF doesn’t work for you, there are so many variations available to try.
This post was written by Dr. Melissa A Murphy, PhD, a dietetic intern in rotation with Shaw Simple Swaps.
Dr. Murphy has a PhD in Nutritional Science, is an AFAA certified personal trainer and is currently completing her dietetic licensing requirements. She teaches nutrition and basic sciences at Bastyr University and has a background in community nutrition, food service and clinical nutrition research. Her nutrition practice is supported by science-based research, naturopathic medicine ideals and ayurvedic/eastern medicine.
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