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Does Fasting Work

What you need to know about intermittent fasting

There are so many different dietary patterns out there that claim to help with weight loss and disease prevention: low-fat, low-carb, ketogenic, paleo, whole 30, vegetarian, vegan, DASH, Mediterranean, MIND, etc. Before you embark on a trend or therapeutic diet for weight management, let’s talk about one simple change you can make now that will get the ball rolling on weight loss – Intermittent fasting, and does it even work?

You may be used to eating three meals every day, plus snacks to at least reach your RMR (Resting Metabolic Rate) of calories needed to sustain body functions. That’s a pretty common dietary pattern. With intermittent fasting you are still reaching the same calorie intake goals but adjust the timing of your meals to stay on a consistent schedule within a smaller eating window.  Your scheduled period may be 11am – 7pm for example with fasting from 7pm to the following morning at 11am.  Unlike most other popular diets, intermittent fasting tells you when to eat, not what to eat.

Many people report that intermittent fasting can help them in several ways:

  • Stay on track with a shorter window to consume calories
  • Control cravings or even eliminate them
  • Balance hormone fluctuations that can leave them feeling “hangry” when they have waited too long to eat
  • Steady weight loss
  • More energy
  • Better sleep

Sound interesting?

Let’s dive into some of the pros and cons of intermittent fasting and find out if it actually works!

How to intermittently fast

Most of the diets that help achieve weight loss work by reducing the number of calories consumed. The challenge with this strategy is that when you reduce your calories below your RMR (Resting Metabolic Rate) consistently over time, you also run the risk of losing muscle.  That lean muscle lost impacts our ability to burn calories when at rest sitting on the couch during movie night.  Intermittent fasting is a way of limiting energy intake (requiring fasting) for certain durations of time (intermittently).  There are several different types of intermittent fasting.

Intermittent fasting essentially means changing the timing of all of your calorie intake, or skipping meals on a regular basis, sometimes weekly, or monthly. Here are a few different approaches:

  • Time-restricted feeding—Having all of your meals during an 8 to 12 hour window each day, drinking only water the rest of the day.
  • Alternate day fasting—Eating normally one day but only a minimal amount of calories the next; alternating between “feast” days and “fast” days.
  • 5:2 eating pattern—Consuming meals regularly for five days per week, then restricting to no more than 600 calories per day for the other two. This happens by eating very little and drinking only water on those two fasting days.
  • Periodic fasting—Caloric intake is restricted for several consecutive days and unrestricted on all other days. For example, fasting for five straight days per month.

Benefits of intermittent fasting

Studies show that intermittent fasting can achieve weight loss. The success is similar to other diets that focus on restricting certain food groups or significantly lower calories, but without the risks of developing a disordered eating pattern, or loosing muscle mass.

Overall, research on the effect of intermittent fasting and how it works for overall health is still emerging as to whether, in addition to some weight loss for some people, it can also prevent disease or slow down aging.

My recommendation is to consume the same amount of calories daily – not below your RMR – in a shorter 8-hour window with an occasional full day fast of 600-800 calories once per month or every other month.

Most of the research on calorie restriction and intermittent fasting has been conducted in cells (e.g., yeasts), rodents, and even monkeys. Some, but not all of these studies show it may help to build exercise endurance, immune function, and live longer. It also seems to help resist some diseases like diabetes, heart disease, certain cancers, and Alzheimer’s.

When it comes to clinical studies (those done in people) on intermittent fasting, most have been pretty short—a few months or less. What we know so far is that it may help with markers of inflammation (C-reactive protein), diabetes (blood glucose levels and insulin sensitivity), and help to reduce high blood pressure and cholesterol.

When it comes to weight loss, intermittently fasting seems to work just as well. Researchers think that eating this way decreases appetite for some people by slowing down the body’s metabolism. With a smaller appetite, you simply eat less and that is going to help you lose weight. Other people who intermittently fast struggle with, and are much more uncomfortable during the fasting days, and some animal studies show that when they were allowed to eat as much as they wanted, many overate. 

For this reason, my recommendation is to consume the same amount of calories daily – not below your RMR – in a shorter 8-hour window with an occasional full day fast of 600-800 calories once per month or every other month.

What about extending the lifespan of humans? Those studies haven’t been done yet, so we simply don’t know the effects of intermittent fasting on our lifespan.

How intermittent fasting affects health

Naturally, our bodies have survival mechanisms allowing us to adjust to periods of fasting. This has been necessary, as throughout history, humans have endured many periods where food was scarce.

What happens when we don’t take in sufficient calories is that our body starts using up stored carbohydrates called glycogen. The liver stores enough glycogen to last about 12 to 16 hours before it runs out of fuel. Beyond 16 hours, the body switches fuels and begins to use fat as an energy source.

At this time, our metabolism shifts from a carbohydrate-burning state to a fat-burning state. Some of the fat is used directly as fuel, while some is metabolized into biochemicals called ketones. This new fat-burning metabolic state is called ketosis. The state of ketosis brings on other changes throughout the body. It’s these changes that are thought to underlie some of the health benefits seen with intermittent fasting.

Ketones are a more efficient source of energy for our bodies than glucose is and so they can help keep many of our cells working well even during periods of fasting. This is particularly true for brain cells and this may be part of the reason some animal studies show protection against age-related declines like Alzheimer’s.

Ketones may also help to ward off some cancers and inflammatory diseases like arthritis. They are also thought to reduce the amount of insulin in the blood which may help protect against type 2 diabetes. On the other hand, too many ketones may be harmful, so more research is needed to better understand the links between fasting, ketones, and health.

On a molecular level, intermittent fasting may extend lifespan in animals because of its effect on the DNA in our genes. Over time as we age, the way our genes are switched on and off changes. It appears that, in animals, restricting calories may slow down these age-related changes and help them to live a bit longer.

More research is underway to better understand the effect of fasting on these biological processes.

Before you start intermittently fasting

As with all major dietary changes, be sure to discuss it with your healthcare professional.

Before considering intermittent fasting, know that there are certain conditions that can make it dangerous. For example, if you have diabetes you need to eat regularly to maintain your blood sugar levels, so fasting is not recommended. Also, if you’re taking certain medications like diuretics for high blood pressure or heart disease, intermittent fasting increases your risk for electrolyte abnormalities.

Intermittent fasting is also not recommended for anyone who is under 18, has a history of eating disorders or anyone who may be pregnant or breastfeeding.

Of course, whenever you change your diet you may experience side effects. Some side effects of people who restrict their calories or start intermittently fasting include fatigue, weakness, headache, reductions in sexual interest, and a reduced ability to maintain body temperature in cold environments.

Beyond the health risks and side effects, fasting is simply hard to do voluntarily—especially when it’s for two or more days. Some people may have a natural tendency to indulge too much on their “feast” days which can negate some of the benefits of fasting.  Therefore I don’t recommend severe calorie restricted fasts more than once every 1-2 months and prefer time restricted (8-hour window) over all other types of fasting.

According to the National Institutes of Health, “More research will be needed to determine the long-term impact of the diet on human health and provide information on when and how such a diet might be applied.”

Nutrition tips for intermittent fasting

Intermittent fasting can be hard. One thing that can help is having a social support network—especially for those days when you’re fasting.

Although the premise of intermittent fasting is to restrict when you eat, not what you eat, the quality of your food choices is still very important. Regardless of your eating style and preferences, you still need all of your essential nutrients. Intermittent fasting is not a good reason to eat a lot of the high-calorie nutrient-poor foods we all sometimes crave. I recommend eating adequate amounts of lean proteins, healthy fats, fruits, vegetables, legumes, and whole grains. Also, avoid refined sugars and refined grains. 

Recipe and Meal Ideas

My favorite sources of inspiration often come from bloggers such as vegan blog Oh She Glows for her unique way of creating dairy free – SUPER tasty – recipes, Against All Grain recipes that are often grain and dairy free as well as paleo blogs for their use of whole food and lean proteins.

Aim to consume foods that came from the ground or had a mother – clean, whole food.

Kaizen Nutrition & Wellness meal planning tools are another great option to source new recipes, modify recipes for additional guests or eating for 1, or all-in meal planning for the week.  The “Total Custom” planner has access to the full database of recipes.  Start a free trial today, and if you LOVE IT, let us know and we will extend it to you for free (we love a good deal!):  CLICK HERE FOR MEAL PLANS

Cooking videos can be a great way to improve your culinary skills and feel comfortable with trying new ingredients.  Visit our website for step-by-step instructional videos, shopping lists (and substitution ideas) recipes to download:

Convenience vs. processed food is a question I get often.  What is the difference, and can this be a tool for preparing healthy meals – YES!  The difference is this.  If you purchase a meal kit from the grocery that has raw chicken, diced squash, cooked rice, diced apricot, sauce and raw almonds – you are purchasing whole food as long as the sauce doesn’t contain lots of ingredients you cannot pronounce or preservatives.  This is a perfect example of a convenience meal – easy to make, quick, healthy.  Processed food in contrast is a frozen entrée high in saturated fat, carbohydrates, sodium with 3 or more ingredients you cannot pronounce as well as preservatives.

Some of my favorite convenience products:

  • Meal Kits to prepare at home from grocery stores
  • Applegate farms lean, low sodium lunch meat
  • Applegate farms chicken breakfast sausages
  • Kevin’s Natural Foods

Worst case, swing by the grocery for lunch or dinner and pick up a salad, sushi wrap, prepared foods hot bar from stores such as Publix, Whole Foods or Weaver Street Groceries.  You will save yourself from picking up processed fast food, high in sodium, saturated fat and sugars. 

Be sure to balance ½ a plate non starchy veggies, ¼ plate higher carb foods such as beans, pasta, potatoes with ¼ plate of lean protein and some healthy fats from avocado or nuts and “digestives” such as vinegar or yogurt with probiotics.

Final thoughts from your Dietitian

The main reason for any dietary change is to have a sustainable and healthy lifestyle that helps you meet your health goals. Whether you’re looking to lose weight or prevent disease, intermittent fasting is one eating style that may work for you. The most important thing with any diet is to get all of your essential nutrients, appropriate amounts of food, and enjoy your lifestyle in the long run.

Any diet or eating pattern that helps some people may not have the same effect on everyone. That’s why it’s important to not make any significant dietary changes without consulting your healthcare professional or dietitian.

Knowing your RMR (Resting Metabolic Rate) will help you understand how many calories you should be consuming so that you can maintain muscle, while adjusting the timing of your meals with intermittent fasting.  We can measure this as part of a nutrition consultation at no additional cost to you.  Visit our website to learn more about the MedGem metabolic analyzer by visiting our website:  Contact our office assistant Kara at 919-234-7448 if you are interested in scheduling an appointment to have this test done in our office.  It is a fasting test so appointments are limited to 8, 9 and 10am Tuesday – Saturday.

Yours in Health,

Jill Brown, MS RD IFNCP

Hillsborough l Wake Forest l Telehealth

#kaizennutrwell #hillsboroughdietitian #integrativemedicine #nutrition #nutritionist #dietitian #rootcause #foodsensitivity #hormonehealth  #organic #essentialoils #guthealth #mealplan #cleaneating #longevity #herbalmedicine #complementarymedicine #nourish #healthyfood #immuneboosting #lifestylemedicine #prepareyourhealth #kaizenblog #nourish #nutrition #eat #mealprep #mealplan #healthyfood #food #lovetoeat #simplefood #realfood #plantbased #wholefood #healthychoices #vegan #vegatarian #follow #photooftheday #motivation


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