Low-carb diets, such as the ketogenic diet, are popular for their potential effects on weight loss and metabolic health. They’re said to be beneficial for controlling blood sugar levels, reducing inflammation, and promoting heart health.
Intermittent fasting (IF) is an equally popular approach that involves cycling between periods of eating and fasting. It has been suggested that it supports brain health, aids weight loss, and improves longevity (3). Unlike low-carb diets, IF doesn’t specify what foods to eat, but rather when to eat them.
So what happens when you combine the two? You get low-carb intermittent fasting (LCIF), a relatively new approach to dieting. This involves following a low-carb diet during eating windows and fasting for extended periods.
However, as with most dietary approaches, it has pros and cons. Here’s what you need to know about low-carb intermittent fasting, its potential benefits, drawbacks, and practical tips for success.
You can absolutely eat carbs while practicing IF. This is because the primary focus of IF is on when you eat, not what you eat.
The way IF works is by cycling between periods of eating and fasting, which can vary in length depending on the type of IF you’re following.
During the fasting period, you’re encouraged to drink water or other non-caloric beverages, but food intake is restricted. However, once the fasting period ends, you’re free to enjoy a healthy meal that can include carbs.
IF is an eating pattern, not a diet. Unlike diets that restrict certain food groups or rely on calorie counting, IF does not limit what you eat.
This flexibility allows people to follow IF while still maintaining their preferred dietary choices and lifestyles.
In addition, consuming healthy carbs during the eating window can provide a variety of nutrients our bodies need (2).
Carbs are an important source of energy and a major fuel for the brain and muscles, and they help with physical and mental performance. They also contain essential vitamins and minerals such as B-vitamins, iron, magnesium, and potassium (2).
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Yes, you can do low-carb and IF; this is what’s known as low-carb intermittent fasting (LCIF).
LCIF involves following a low-carb diet during eating windows and fasting for extended periods. This approach helps combine the potential benefits of both IF and low-carb diets.
Combining intermittent fasting and low carb has 6 potential advantages. You may experience weight loss, better digestion and gut health, improved brain function, reduced inflammation, increased energy levels, and lower risk of chronic diseases.
Intermittent fasting helps you lose weight by restricting the amount of time you can eat during the day. It creates a calorie deficit by reducing the number of overall calories you consume and forcing your body to burn fat for energy during the fasting period (5).
Adding a low-carb diet to this equation can further enhance weight loss. By limiting your carbohydrate intake, you decrease insulin production and increase the breakdown of stored fat for energy. This is believed to lead to a more efficient and rapid weight loss process (1).
Low-carb diets are often easier on the digestive system than high-carb diets. The lower intake of processed foods and sugar may improve gut health for some people and reduce digestive issues such as bloating, constipation, and diarrhea (1).
Intermittent fasting also allows the digestive system to rest and repair during the fasting period, potentially leading to improved gut health. Research into the gut microbiome has proven that diet composition can affect the makeup of the gut microbiome, which influences overall gut health (8).
Both low-carb diets and intermittent fasting have been linked to improved brain function and they may work even better when combined.
For one, low-carb diets provide the brain with a steady source of energy through the production of ketones, which are an alternative to glucose. Some people feel that this leads to improved focus, mental clarity, and reduced brain fog (5).
Intermittent fasting may also trigger the production of BDNF (brain-derived neurotrophic factor), a protein that promotes the growth and protection of neurons in the brain. This may improve cognitive function and even protect against age-related brain diseases such as Alzheimer’s (7).
Inflammation is the body’s natural response to injury or illness. However, chronic inflammation has been linked to several health issues such as heart disease, diabetes, and arthritis (5).
Both low-carb diets and intermittent fasting are believed to have anti-inflammatory effects on the body. Low-carb diets may reduce the production of pro-inflammatory chemicals and intermittent fasting may promote cellular repair processes that can decrease inflammation (1).
Many people have reported an increase in energy levels when following a low-carb and intermittent fasting diet. This could be due to several factors such as improved blood sugar control, increased fat-burning for energy, and better sleep quality (5).
By reducing the intake of refined carbohydrates and sugar, which often lead to energy fluctuations, and promoting the production of ketones during fasting periods, you can experience sustained energy throughout the day (1).
In our blog post ‘17/7 Intermittent Fasting’, we highlight how beneficial IF can be for increasing energy levels.
By promoting weight loss, better gut health, improved brain function, and decreased inflammation, this combination can contribute to a healthier overall lifestyle and may reduce the risk of developing certain chronic diseases (5).
In addition, some studies have suggested that intermittent fasting and/or low-carb diets may improve insulin sensitivity and blood sugar control in individuals with or at risk for type 2 diabetes. This suggests that this approach may be beneficial for managing and potentially reversing this condition. However, it is essential to consult your healthcare provider before you make any changes to your diet or eating schedule if you have diabetes or are on medications that affect your blood sugar.
Read more: Green Tea Intermittent Fasting: Benefits and Side Effects
While there are many potential benefits to combining low-carb and intermittent fasting, there are also some drawbacks to consider:
One of the main challenges with this approach is adapting to a new way of eating. Both low-carb and intermittent fasting can be challenging for those who are used to a traditional three-meal-a-day diet.
It may take time for the body to adjust to changes in eating patterns and food choices, which can lead to fatigue, headaches, and hunger during the initial stages.
In the later stages, negative side effects can include constipation, bad breath, and electrolyte imbalances.
Restricting certain food groups, such as carbohydrates, can lead to nutrient deficiencies if not carefully planned (4). Carbs are a major source of several essential vitamins and minerals, so it’s important to make sure you still get these nutrients through other food sources or supplements.
In addition, intermittent fasting may lead to a lower intake of certain nutrients if not carefully planned. It’s essential to ensure that your eating windows include a variety of nutrient-dense foods to meet your body’s needs.
Our Vegetarian Intermittent Fasting Guide has pointers on how you can follow this diet without meat or animal products when they are such an important source of nutrients.
Following a low-carb diet and intermittent fasting may also trigger overeating during eating periods. This can happen if you feel excessively hungry after a fast or if you restrict certain foods too much and end up overeating them during your eating window (4).
It’s important to listen to your body’s hunger cues and make sure you consume enough calories and nutrients during your eating periods to prevent overeating.
Low-carb diets may also raise concerns for heart health, as they often promote the consumption of high-fat foods, and many people may turn to unhealthy saturated fats to replace carbohydrates (6).
High-fat cheeses, processed and red meats, fried foods, and other high-fat options may increase the risk of heart disease, particularly if they’re consumed in excess.
Low-carb high-fat intermittent fasting (LCHF-IF) diets may also lead to an increase in cholesterol levels, which can be a risk factor for heart disease (6).
Consuming healthy fats from sources such as avocados, nuts, and olive oil rather than saturated fats is important for maintaining heart health while following this approach.
Like any diet or lifestyle change, low-carb intermittent fasting may not be suitable for everyone. People with certain medical conditions, such as diabetes or eating disorders, should consult a healthcare professional before starting this approach.
In addition, some individuals may experience negative side effects such as dizziness, fatigue, and irritability during the initial stages of adapting to this new way of eating.
Our Intermittent Fasting 101: A Beginner’s Guide is a great resource for those who are new to this approach and looking to learn more about its potential benefits and how to safely incorporate it into their lifestyle.
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The main tip for success while on LCIF is to plan and prep. You can’t go wrong when you intentionally choose healthy food options and make sure you have them readily available during your eating windows.
Below, we provide some solid tips to help make your low-carb intermittent fasting journey smoother.
To ease into this diet, it may be helpful to start with either a low-carb or intermittent fasting approach first. This will help your body adapt gradually without overwhelming it with too many changes at once. Once you feel comfortable and have adjusted to one approach, you can try incorporating the other.
We recommend starting with a low-carb diet first as this may be most challenging. Carbs are often a major part of traditional diets, so cutting them out can be a major adjustment. Once you’ve successfully transitioned to a low-carb diet, try incorporating intermittent fasting.
As previously mentioned, planning and prepping meals is essential for success on this diet. This helps prevent impulsive food choices during your eating windows and ensures that you consume nutritious meals that are aligned with your goals.
Set aside time each week to plan your meals and make a grocery list of the necessary ingredients. Preparing some meals ahead of time and having healthy snacks on hand can also make it easier to stick to this lifestyle.
Here’s a sample 7-day low-carb intermittent fasting meal plan that you can use to get started (feel free to adjust according to your preferences and dietary needs).
Note: This meal plan assumes a daily eating window from 12:00 pm to 6:00 pm, followed by a fasting period from 6:00 pm to 12:00 pm the next day.
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
It’s important to remember that hydrating is important during both eating and fasting periods. Drink plenty of water throughout the day, and feel free to incorporate unsweetened teas or black coffee during fasting hours.
Dining out or going to events with friends and family can be challenging when you’re following a low-carb intermittent fasting diet. To make things easier, plan ahead by checking the menu of the restaurant beforehand and choosing a lower carb option or opting for a smaller portion size. You can also bring your own healthy snacks if necessary.
A common pitfall when dieting is to go too strict or extreme straight away, which can lead to burnout and eventually giving up. You should adopt a gradual approach and listen to your body’s needs. If you feel you need more carbs on certain days, then you should incorporate them in moderation. The key to long-term success is finding balance and sustainability.
Read more: Intermittent Fasting and Running: A Winning Combination or a Terrible Mistake?
Your body enters ketosis (a metabolic state where it burns fat for energy) after approximately 12-16 hours of fasting, so a 16-hour fast can be beneficial for those who are following a keto diet.
Note: the transition isn’t instantaneous – your cells don’t go from burning sugar to burning fat in an instant. The average time to reach ketosis on a ketogenic diet is 2-11 days, but it can take longer for some people.
Both low-carb and intermittent fasting are said to have various benefits, but it’s ultimately dependent on an individual’s goals and preferences.
Some people may see better results with a low-carb approach, while others may find success with intermittent fasting. It’s best to experiment and find what works best for you.
Incorporating both is also a viable option, as LCIF can provide the benefits of both methods. However, it’s important to listen to your body and make sure you’re not overdoing it with too many changes at once.
Yes, you can do intermittent fasting without following a keto diet. Intermittent fasting can be done with any type of healthy eating approach, including low-carb, vegetarian, and vegan diets.
It’s important to keep in mind that while you can eat anything you want when doing IF, what you eat during your eating windows is still important for overall health and weight management.
The strongest IF method (one where you reap the most benefits) is any form where you successfully fast for at least 16 hours a day, as this is believed to be when the body switches into ketosis to burn fat for energy (3).
Other benefits such as reducing inflammation and improving insulin sensitivity may also be seen with longer fasting periods (5). However, it’s important to find a method that fits with your lifestyle and can be maintained in the long term.
To do an intermittent fasting low-carb diet:
Combining low-carb and intermittent fasting may offer a wide range of potential health benefits, from weight loss and improved digestion to reduced inflammation and lower risk of chronic diseases.
However, it’s important to consider the potential drawbacks and consult a healthcare professional before you make any major changes to your diet. By finding a balance that works for you and your body, you can potentially achieve better overall health and well-being.
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