Intermittent fasting and the keto diet are both popular weight loss options that boast plenty of success stories. Some people have seen fantastic results with keto, while others advocate intermittent fasting. Some dieters even do both.
But, when it comes to intermittent fasting vs keto, which approach wins?
The Keto Diet
Keto has been exceptionally popular lately, so let’s start there.
As you probably know, this is a very low-carb and high-fat diet. It relies heavily on healthy fats, while dramatically lowering your carb intake.
Your carbs normally need to be under 50 grams of total carbs per day (or 20-35 grams net carbs). You can use a keto calculator (like this one from Ruled.me) to work out your daily macronutrient intake.
The goal is simply to be in a state of ketosis. In ketosis, your body relies on fat for fuel. The process produces ketones, which have been linked to health benefits. There are various keto symptoms and testing processes that can help you know when you’re in ketosis.
Advantages of Keto:
- Keto is popular, so there are many amazing recipes and recipe books, along with various articles and blogs to help guide you through.
- The strict nature of keto works well for some people, as they know exactly what they can and cannot eat.
- Keto diets can promote weight loss while improving heart disease risk factors (1,2,3).
- Keto can be easier than low-fat diets in the long-term, as the food tends to be more satisfying and you feel hungry less often.
- Foods on a keto diet are often healthier than high-carb foods.
Disadvantages of Keto:
- To get your carb intake low enough, you need to cut out many common foods (including bread, rice and pasta). This requires some creativity and plenty of meal planning. While there are fantastic alternatives for any non-keto ingredient or recipe, there is still considerable time and work involved.
- Keto alternatives don’t always taste as good as the regular thing.
- Keto is an all-or-nothing approach. Going over your carbs a little may kick you out of ketosis and it takes time to reach ketosis again.
As the name suggests, intermittent fasting focuses on some periods where you’re abstaining from food. The idea is that fasting promotes various healthy processes in our bodies, including autophagy.
Many of us don’t get these benefits normally, as modern society is so focused on eating. This often includes three meals per day (or even more) plus snacks.
The gaps between our eating are often very short indeed. With intermittent fasting, you’re increasing these gaps, which has significant health implications.
Intermittent fasting falls into various protocols, including the following:
- 16:8. You fast for 16 hours each day and eat within an 8-hour window. This often involves skipping breakfast and then having a larger lunch and dinner.
- 5:2. You fast for two days each week and have five normal days. The fasting days aren’t complete fasts. Instead, you’re normally consuming around 500 or 600 calories per day.
- Alternate day fasting. This is similar to 5:2, except your fasting and regular days are alternated.
- 24-hour fasting. With this approach, you’re cutting out all food for a 24-hour period. You might do one or two such fasts a week.
The style isn’t as hard as it sounds, especially if you follow the 16:8 protocol. With this approach, you could choose to have your first meal at noon and your second meal at 7:30 pm. You might have something small between them or you might not.
The hardest part is waiting for that first meal. This gets much easier over time. Some people even find that they’re not hungry until right before it's time to eat.
Intermittent fasting is also very flexible. You can choose whichever protocol you like and modify it, such as doing a 17:7 or an 18:6 version. You might follow the schedule strictly or change it as your needs shift.
Advantages of Intermittent Fasting:
- The style is incredibly flexible. You get to choose how strictly you follow the approach, the food you eat and your fasting hours.
- Fasting has been linked to various health benefits, including decreased disease risk (4,5,6,7), improved brain health (8) and a longer lifespan (9).
- Intermittent fasting doesn’t affect social interaction as much as many other diets. You’re often just missing breakfast, which is typically consumed alone or with family. You’re eating regular meals for lunch and dinner. This is much easier than needing to refuse a dinner invitation or carefully choosing what you eat.
- The approach can be a simple way to decrease calorie intake, without the need to count calories.
- The fasting days or times give you more flexibility with the meals that you consume.
Disadvantages of Intermittent Fasting:
- Some people cope poorly with being hungry. They may become irritable and be unable to concentrate.
- There is a risk that you’ll end up eating too much due to the hunger from missing a meal. This doesn’t apply in practice for most people (10), but it may be significant for some individuals. You’ll need to pay close attention to how you respond to the restriction.
- Intermittent fasting can be a poor choice for anyone susceptible to eating disorders, as it promotes being hungry.
- The process can promote hormonal imbalances.
Intermittent Fasting and Women
Intermittent fasting can be problematic for some people. Because the process mimics periods of starvation, it can disrupt hormone production. This is particularly significant for women, as their bodies need to support reproduction. As a result, some women experience missed periods, hormone imbalance, sleeplessness and anxiety when intermittent fasting.
Decreasing the intermittent fasting window or fasting on fewer days can reduce the risk of issues. Increasing healthy fat intake may also help. The best approach is to simply make changes until you find an approach that works well for your body.
Some people will find that there are no issues at all, while intermittent fasting may not be viable for others. We’re all different.
Combining the Two
Intermittent fasting focuses on when you eat. Keto focuses on what you eat.
They’re not mutually exclusive. Many people do both at the same time. This lets you combine the benefits. In fact, keto and intermittent fasting both help you to get into ketosis.
Advantages of Keto Intermittent Fasting:
- The combination isn’t as difficult as it sounds. Keto and intermittent fasting naturally complement one another. Many people find that the extra energy from keto means that there are no downsides to skipping breakfast.
- Keto often reduces hunger, which can make intermittent fasting easier to stick to.
- Intermittent fasting often means you’re having larger meals and eating less frequently. This allows you to fully enjoy all of the fantastic keto recipes out there, including keto fat bombs, snacks, lunches, desserts and more.
- The combination may help you stick to your macros, as there are fewer meals to worry about.
Disadvantages of Keto Intermittent Fasting:
- Having to watch what and when you eat can be frustrating.
- You lose some of the flexibility that intermittent fasting normally offers.
- The combination may be particularly difficult if your life is unpredictable.
What’s the Best Approach?
Keto and intermittent fasting both have benefits, that much is clear. Both can also be easier than they sound. The ideal approach would be an intermittent fasting keto diet. This gives you the best of both worlds.
But… nutrition is complex.
Every person’s situation and needs will be different (11). Plus, the best diet for your health is always the one that you can stick to. Whatever approach you take should be tailored around your own personal needs. For example:
- Bulletproof Intermittent Fasting applies many intermittent fasting principles but includes drinking Bulletproof coffee in the morning instead of skipping the meal. This can be easier to follow and reduces any negative hormonal effects for women.
- Other people follow a 16:8 approach to intermittent fasting, while also having a keto coffee first thing in the morning. The keto coffee breaks your fast, so the style isn’t quite the same as intermittent fasting. But, the approach is much easier and you still get most of the benefits.
- Some people use intermittent fasting to get back into ketosis faster, but don’t follow it in the long-term.
- You might follow intermittent fasting consistently and only sometimes follow ketosis too – or vice versa.
The best answer is often trial and error. Pick the approach that sounds right to you and see how it affects your health and weight loss. You can then tweak it to best suit your needs.
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2 thoughts on “Intermittent Fasting vs Keto: Which Should You Choose?”
A nice article. I’d never really considered the either / or of Keto vs Intermittent Fasting. I’ve always had the best success by combining the two. Thanks for the great article
That’s very true. Many people do combine the two with great success. That seems to be the ideal approach, as they complement one another nicely.