Intermittent fasting is one of the most talked-about approaches to nutrition. Depending on who you ask, it can supposedly help you lose weight, improve your blood sugar, lower inflammation, extend your lifespan, improve your brain, and possibly organize your sock drawer.
Okay, maybe not that last one.
Let’s try to separate the interesting science from the internet hype.
The truth is that intermittent fasting is neither a miracle nor automatically a bad idea. For some people, changing when they eat can provide a very useful and sustainable structure. For others, fasting may feel miserable, interfere with adequate nutrition, worsen their relationship with food, or simply offer no advantage over a more traditional eating pattern.
Before we get into the nuances, let’s just take a second to be sure we are all on the same page.
What is Intermittent Fasting?
Intermittent fasting (IF) is an umbrella term for eating patterns that alternate between periods of eating and periods of little or no caloric intake.
Unlike many diets, intermittent fasting focuses primarily on when you eat rather than what you eat.
A typical overnight fast already happens naturally when you finish dinner, sleep, and eat breakfast the next day. Intermittent fasting simply extends or structures that fasting period.
There is no one-size-fits-all approach to fasting. One of the most commonly studied forms is time-restricted eating (TRE), which involves limiting the time spent eating each day, often to an 8- to 10-hour window. Other approaches involve fasting or severe calorie restriction on certain days of the week.
- 12:12: Fast for 12 hours and eat within a 12-hour window. This is often a gentle starting point and may simply mean cutting out late-night eating.
- 14:10: Fast for 14 hours and eat within a 10-hour window.
- 16:8: Fast for 16 hours and eat within an 8-hour window. This is one of the most popular forms of time-restricted eating.
- 18:6 or 20:4: Shorter eating windows with longer fasting periods. These approaches are more restrictive and aren’t necessarily better. These may also be harder to maintain and can make it very challenging to consume enough protein, fiber, and other nutrients.
- 5:2 fasting: Eat normally five days per week and significantly reduce calorie intake on two days.
- Alternate-day fasting: Alternate between regular eating days and fasting or very-low-calorie days.
- OMAD (One Meal a Day): An especially restrictive approach that involves consuming most or all of your daily food in one meal. This form of fasting has not been studied as extensively as other more common approaches, and its extreme nature makes it difficult to meet energy and nutrient needs.
Should I try intermittent fasting?
Maybe. Intermittent fasting can be a reasonable eating pattern for some people, but it isn’t necessary for good health and it’s not automatically better than other approaches to eating well.
Some people find that fasting fits naturally into their lives. Maybe you’re not particularly hungry in the morning, or you prefer a larger lunch and dinner.
Perhaps having a defined eating window helps you cut back on mindless evening grazing or gives your day a little more structure.
Research suggests that intermittent fasting can support weight loss and improve some cardiometabolic health measures. (More on that below) However, the benefits are generally similar to those seen with other approaches that reduce calorie intake, and the research has not shown that fasting is a uniquely superior way to improve health.
So, should you try it?
Consider whether fasting makes eating feel simpler and more manageable or whether it makes you feel overly hungry, restricted, or preoccupied with food.
The best eating pattern is one that supports your nutritional needs, fits your lifestyle, and is something you can comfortably maintain over time.
In other words, you don’t need to fast to be healthy. But if a moderate fasting schedule makes healthy eating easier for you, it can be one tool worth considering.
Intermittent fasting may be worth experimenting with if:
- You enjoy having a predictable eating schedule.
- You naturally prefer fewer meals.
- You aren’t particularly hungry early in the morning.
- A defined eating window helps reduce mindless or late-night eating.
- You can still meet your calorie and nutrient needs.
- Fasting doesn’t lead to bingeing or feeling out of control around food.
- The schedule fits reasonably well into your life.
Tip: The best fasting schedule isn’t necessarily the longest one. Are you forcing yourself to ignore hunger all morning only to become ravenous and eat everything in sight at night? If so, that particular fasting schedule may not be working for you.
It’s the one that supports your goals without making your life harder than it needs to be.
What are the potential health benefits of intermittent fasting?
Weight and body fat
Intermittent fasting can support weight loss and fat loss. But here’s an important point:
Research suggests that fasting can be effective for weight management, but no more than other approaches to calorie restriction.
For some people, the benefit may be more about the behavioral aspect. A shorter eating window can naturally reduce opportunities to eat and make it easier to reduce overall calorie intake without tracking everything.
Blood sugar and metabolic health
Research suggests that some fasting approaches may improve markers related to blood sugar regulation and insulin sensitivity, particularly among people with overweight, obesity, insulin resistance, or other metabolic risk factors.
If you are taking medications for blood sugar management, it’s important you discuss fasting with your provider before starting, as they may need to adjust dosing or timing for you.
Some research also suggests that when you eat may matter. Eating earlier in the day may better align with our circadian rhythms than concentrating most food intake late at night.
Heart health
Intermittent fasting has also been associated with improvements in some cardiometabolic risk factors, including:
- Blood pressure
- Blood sugar and insulin
- Triglycerides
- Body weight
- Waist circumference
Important: The results vary depending on the type of fasting, the person being studied, and whether weight loss occurred.
Digestive health
Early research suggests intermittent fasting may support gut microbiome diversity, while also reducing bloating and some IBS symptoms. One possible explanation is that longer breaks between meals may support the gut’s natural rhythms and give the digestive system more time between meals. However, the research is still emerging, and from experience we know that fasting results can vary from person to person.
Who Should Avoid Fasting or Get Medical Guidance First?
Fasting isn’t appropriate for everyone.
You should generally avoid intermittent fasting or talk with your healthcare provider first if you are:
- Pregnant or breastfeeding
- Under 18 and still growing
- Underweight or struggling to maintain weight
- Living with or recovering from an eating disorder
- Taking insulin or other medications that can cause low blood sugar
- Living with type 1 diabetes
- Managing type 2 diabetes with medications that may need adjustment
- Experiencing recurrent low blood sugar
- Managing a medical condition that requires regular food intake
- Recovering from illness or injury
- An athlete or highly active person who struggles to meet energy needs
If fasting causes persistent dizziness, weakness, extreme fatigue, significant irritability, menstrual changes, or intense preoccupation with food, fasting is not right for you. There are no bonus health points for suffering through a fasting schedule that clearly isn’t working for you.
Is Fasting Different for Males and Females?
There are biological differences between males and females, and reproductive function can be sensitive to inadequate energy availability. But that does not mean intermittent fasting is automatically harmful to all women.
The biggest consideration may be whether fasting contributes to chronic under-fueling.
Women who are already:
- Eating too little
- Exercising intensely
- Losing weight rapidly
- Experiencing menstrual irregularities
- Struggling to meet their energy needs
need to be especially cautious.
How to Get Started With Fasting: 3 Steps
There’s no need to wake up tomorrow and immediately skip breakfast until noon. Instead, try easing into a longer fasting window.
Step 1. Start with your normal overnight fast
Pay attention to how long you naturally go between your last meal of the day and your first meal the next morning.
You may already be fasting for 10 to 12 hours.
Step 2. Extend gradually
Try adding 30 to 60 minutes at a time.
For example:
Week 1: 12-hour overnight fast
Week 2: 13 hours
Week 3: 14 hours
Then pause and ask yourself:
- How is my energy?
- Am I still able to eat enough?
- How is my exercise performance?
- Am I becoming overly hungry?
- Am I thinking about food constantly?
- Does this schedule actually make my life easier?
Even though the 16:8 is most common, there is no prize for reaching 16 hours. You may find that a 12- or 14-hour overnight fast feels great and brings you benefits.
Step 3. Make your meals count
A shorter eating window makes meal quality even more important.
Aim to include:
- Protein
- High-fiber carbohydrates
- Fruits and vegetables
- Healthy fats
- Enough overall food to meet your needs
Eating balanced, satisfying meals can make a big difference in how you feel and function. Work with your Well Balanced dietitian to make sure you are meeting your unique nutrition needs.
What should you expect when you start intermittent fasting?
Some people may notice:
- Hunger at their usual meal or snack times
- Increased thoughts about food
- Mild irritability or “hangry” moments
- Changes in energy or concentration
- Headaches, especially if hydration or caffeine habits change
Some people find that things improve and hunger becomes more manageable as they adjust to a new eating schedule. Others may discover that fasting simply leaves them feeling miserable.
Know the difference between adjusting and suffering
A little hunger before your next planned meal is not necessarily a problem.
But persistent or significant symptoms such as dizziness, weakness, severe headaches, extreme fatigue, difficulty concentrating, feeling faint, or feeling increasingly preoccupied with food are worth taking seriously.
You don’t get extra health benefits for pushing through a fasting schedule that makes you feel terrible.
Sometimes the solution is as simple as shortening the fasting window. Or fasting may not be the right tool for you at all.
Food for thought
The best question to ask yourself isn’t:
“How long can I go without eating?”
It’s:
“What eating pattern helps me consistently meet my nutritional needs and supports my health goals?”
For some people, fasting may be part of the answer.
For others, breakfast, snacks, and regular meals may work better.
Both can be healthy.
If you’re curious about fasting, consider starting with a simple 12-hour overnight break from eating and paying attention to how you feel.
The goal is to find an approach that works for your body and your life.
Remember, you don’t have to do this alone. We are here to support you! Book a call today to get started!
