What you need to know about intermittent fasting
There are so many different diets 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. But I want to talk about one of the latest (but widely used) trends: intermittent fasting.
You may be used to eating three meals every day, plus snacks. That’s pretty common. With intermittent fasting you can essentially eat how much of whatever you want—but here’s the catch: you have to stay on schedule. With intermittent fasting there are scheduled periods of time when you can eat and others when you have to fast. Unlike most other diets, intermittent fasting tells you when to eat, not what to eat.
And, many people say that it can help lead you to better health and a longer life.
Sound interesting?
Let’s dive into what you need to know about intermittent fasting.
How to intermittently fast
Most of the diets that help achieve weight loss work by reducing the number of calories consumed. Intermittent fasting does the same thing, but in a different way. This way of eating significantly limits calories (requiring fasting) for certain durations of time (intermittently), while allowing little or no restrictions the rest of the time.
Intermittent fasting can essentially involve skipping meals on a regular basis, sometimes daily, weekly, or monthly, but it all depends on the method that works best for YOU. 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. Some people even go as far as restricting the meal window to 6 hours a day.
While this method is one of the most common methods, I generally recommend that female patients don’t limit their eating window to less than 8 hours as this can lead to more stress on the adrenals and thyroid and potentially lead to hormonal imbalances.
This method is a lot easier for people to achieve, especially when your fasting period extends overnight.
Examples of this method include:
Having a 12-hour eating window and a 12-hour fasting window (ex. eating between 7am-7pm)
Having a 10-hour eating window and a 14-hour fasting window (ex. eating from 8am-6pm or 9am-7pm)
Having an 8-hour eating window and a 16-hour fasting window (ex. eating from 10am-6pm or 11am-7pm)
Etc.
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 and herbal teas 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.
One meal a day—This is one of the more extreme types of intermittent fasting. Caloric intake is restricted to a single meal or a very short window of time. It can be much harder to reach your nutrient requirements with this approach.
Benefits of intermittent fasting
Studies show that intermittent fasting can help achieve weight loss as well as aid in restoring metabolic flexibility. The success with weight loss, however, is similar to other diets.
Overall, research on the effect of intermittent fasting on people’s health is still emerging, but there is evidence to suggest that it may also prevent disease or slow down aging.
Most of the research on calorie restriction and intermittent fasting have 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, and sample sizes are small. But 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. In fact, a small study involving the 5:2 intermittent fasting approach showed to be more effective at lowering postprandial triglycerides than continuous energy restriction. Another study showed that calorie restriction plus 3 days fasting weekly was more effective than either alone for weight loss and improving cardiometabolic markers in overweight women.
When it comes to weight loss, intermittently fasting seems to work just as well—if not better for some individuals—than other diets. Intermittent fasting can help your metabolism work more efficiently as well as reset your hunger and fullness cues, leading to a smaller appetite. With all things, there also comes challenges. Some people struggle during the fasting days and instead of having a lower appetite, some people may actually overeat during the eating windows.
Studies are still being done on the effects of intermittent fasting on our lifespan and whether or not it can help extend the 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. The increase of ketones in the bloodstream enhances the body’s defenses against oxidative and metabolic stress and initiates the removal or repair of damaged molecules. This impact carries over into the non-fasting period and can improve glucose regulation, increase stress resistance and suppress inflammation.
Fasting overnight for 13-16 hours, syncing with the circadian rhythms, appears to reset the body’s peripheral clocks leading to optimal clock gene expression and enhanced energy metabolism. There was also a study involving 1,066 women from NHANES data that found improved biomarkers of glucose control through nighttime fasting may also reduce breast cancer risk.
More research is underway to better understand the effect of fasting on these biological processes, but so far, several human clinical trials have shown that intermittent fasting can lead to improvements in health conditions such as obesity, diabetes, cardiovascular disease, cancers, neurological disorders, and more.
Before you start intermittently fasting
As with all major dietary changes, be sure to discuss it with your healthcare professional or book a consultation with me. Just Click Here to Schedule a Call.
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.
More research is needed in regards to intermittent fasting, but current research is showing several benefits when it comes to lowering inflammation, lowering risk of chronic disease, aiding in metabolism and weight loss, and protecting our cells.
What you need to know about intermittent fasting: nutrition tips
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. Here are 4 tips to get you started:
Avoid sugars and refined grains: opt for fruits, vegetables, beans, lentils, whole grains, lean proteins, and healthy fats (very similar to a Mediterranean diet pattern).
Let your body burn fat between meals: don’t snack and be active throughout your day. Build muscle tone.
Avoid snacking or eating at nighttime: every day.
Consider a simple form of intermittent fasting: limit the hours of the day when you eat, and for best effect, make it earlier in the day (between 7am-3pm or 10am-6pm, but not in the evening before bed).
Final thoughts
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, lower inflammation, protect your cells, 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. Together, you can find an eating pattern that works best for YOU. If you’re looking to learn more on how you can incorporate intermittent fasting into your plan, book an appointment with me for a free 30 minute discovery call to see how my services can best help you. To do so, BOOK HERE.
