Intermittent Fasting And Keto In Human Evolution
For nearly two million years our ancestors lived in a world teeming with large prey . 3
When a hunt was successful our ancestors feasted, and when the hunt failed, they fasted.
Over eons of human evolution, our ancestors whose brains and bodies functioned the best in fasted states were also the best at hunting and gathering foodand ultimately at surviving and reproducing. This means the genes that shaped their metabolism have been passed along to us.
We see evidence of our bodies adaptation to cycles of fasting and feasting in the way we:
- easily store fat: Our fuel supply in-between successful hunts
- easily go into ketosis: How we convert stored fat and the fat we eat, into fuel during times when carbohydrates and calories are scarce.
- have reduced cognitive ability when not fasting, because our brains are hard-wired to function optimally during times of food scarcity.
Whats The Best Approach
Recommendations vary about the ideal way to fast.
- Some people suggest the eating window style , as it fits well with regular daily patterns. The site Perfect Keto offers important information about how the 16:8 version fits into a keto diet.
- Others recommend alternative day fasting, as it can be less stressful on the body.
There are also alternative patterns, that specifically focus on the keto diet.
For example, the Tim Ferriss 3-Day Fast Protocol is promoted as a fasting method to help people get into ketosis quickly. The approach takes advantage of exogenous ketones and/or MCT oil, along with fasting approaches. You can find full details at the site Eat Move Hack.
You may find other recommended approaches too.
Realistically, the best option is the one that works for you. You might find that a 16:8 or an 18:6 diet is easy. Or, you might prefer to fast less frequently for longer periods of time.
There is no single best way to fast
Who Should Not Fast
Wondering how long is it safe to fast? Stop right there. Some people should not fast at all. First and foremost, always talk to your doctor before engaging in the practice of fasting. Its important to discuss any preexisting health conditions you may have that could be affected by reducing your eating window.
While fasting may provide benefits to some, it is not for everyone.
If you are pregnant, breastfeeding, elderly, have a history of disordered eating or have a chronic health condition, such as type 2 diabetes or heart disease or high cholesterol, consult with your health provider, and discuss supervised fasting before introducing either IF or longer fasts into your life.
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May Lead To More Fat Loss
Combining the diet and the fast may help you burn more fat than the diet alone.
Because intermittent fasting boosts metabolism by promoting thermogenesis, or heat production, your body may start utilizing stubborn fat stores .
Several studies reveal that intermittent fasting can powerfully and safely drop excess body fat.
In an eight-week study in 34 resistance-trained men, those who practiced the 16/8 method of intermittent fasting lost nearly 14% more body fat than those following a normal eating pattern .
Similarly, a review of 28 studies noted that people who used intermittent fasting lost an average of 7.3 pounds more fat mass than those following very low-calorie diets .
Plus, intermittent fasting may preserve muscle mass during weight loss and improve energy levels, which may be helpful for keto dieters looking to improve athletic performance and drop body fat .
Additionally, studies underscore that intermittent fasting can reduce hunger and promote feelings of fullness, which may aid weight loss .
Combining intermittent fasting with a keto diet may help you reach ketosis faster and drop more body fat than a keto diet alone.
Combining the ketogenic diet with intermittent fasting is likely safe for most people.
However, pregnant or breastfeeding women and those with a history of disordered eating should avoid intermittent fasting.
Though some people may find merging the practices helpful, its important to note that it may not work for everyone.
May Smooth Your Transition Into Ketosis
Keto is about switching your body from using carbohydrates for energy, to turning fat into ketones. The typical way to do this is by cutting carbs and increasing fat intake in your diet. For many people this transition can take some time and it comes with a number of unpleasant side effects known as keto flu.
Think of fasting as a way to jump start ketosis.
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Intermittent Fasting On Keto: Important Or Overhyped
Intermittent fasting and the ketogenic diet are two of the top trending eating patterns among dieters and health enthusiasts alike. However, while there are plenty of differences between intermittent fasting vs. keto, they can actually be combined to help amplify results and reach ketosis even faster. In fact, by practicing intermittent fasting on keto, you can take advantage of the unique benefits that both have to offer.
So should I fast on keto? What ingredients belong on the keto diet food list? And how many hours should you fast intermittently? Heres everything you need to know about intermittent fasting on keto, plus how to get started.
Related: Beginners Guide to the Keto Diet
What To Eat While Intermittent Fasting
During your fasting window, you shouldnt eat anything. During your eating window, enjoy nutrient-dense keto foods like healthy proteins, vegetables, and fats.
Avoid breaking your fast with processed foods, carb-heavy meals, and dirty keto foods, as these can hinder the health benefits of fasting in the first place.
Also Check: How Much Weight Do You Lose From Water Fasting
Challenge #: Sleep Issues
Many folks have trouble going to bed hungry, and its not just a psychological quirk. In fact, fasting increases alertness chemicals like adrenaline and orexin-A that can make relaxation difficult.
What You Can Do: Back Off The Fasting. If you cant sleep, consider backing off to an easier fasting regimen. For example, step down to 16/8 from ADF. The benefits of fasting probably dont outweigh the harms of sleep deprivation. When in doubt, listen to your body!
What About Metabolism Slowdown
Were often told that having many small meals per day is critical for weight loss and metabolism. So, dropping down to a small eating window sounds like a bad plan.
But, the small frequent meal idea is a myth. You dont need to eat like that for weight loss. For that matter, short-term fasts can even speed up your metabolism and they help you lose weight.
The main metabolic impact actually comes from weight loss. Your metabolism may decrease when you lose weight especially if you lose a large amount . That effect occurs regardless of how you lose the weight.
Plus, intermittent fasting can help you retain muscle. This can be beneficial for your metabolism and is a key advantage.
Despite the myths, intermittent fasting doesnt slow down your metabolism
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Wont Intermittent Fasting Burn Muscle
That depends on the person and the duration of the fast. During fasting, the body first breaks down glycogen into glucose for energy. After that, the body increases body fat breakdown to provide energy.
Excess amino acids are also used for energy, but the body does not burn its own muscle for fuel unless it has to.49
Some studies, however, suggest that leaner individuals are at higher risk of lean body mass loss, and even reduced metabolic rate. Yet it appears this is less of a concern with overweight subjects.50
How To Follow The Fat Fast
Intuitively, the majority of your calories will derive from fat. You need to ensure they contain healthy fats such as monounsaturated fats, omega-3s and medium-chain triglycerides .
I recommend consulting this guide we have written for the best fat sources when carb intake is limited.
You should also incorporate small portions of high-quality protein sources and fibrous vegetables during a fat fast. Check out our Ketogenic Foods List for which foods are best.
Remember, you should only follow fat fasting for five days maximum most people should only implement this protocol once a month if necessary.
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Keto Diet What Can I Eat And What Not To Eat
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Overview Of Fat Fasting
Fat fasting is a form of fasting typically advised for those who are currently keto-adapted and at a weight-loss plateau.
The protocol of fat fasting entails consuming about 85-90% of your calories from fat while keeping your overall calorie consumption low, generally no more than 1000-1200 calories per day.
We strongly encourage that you follow a fat fast for no longer than 5 days at a time. If you follow a fat fast for any longer, you risk losing significant lean mass and micronutrient deficiencies.
When you begin a fat fast, and youre currently keto-adapted, your ketone values will likely get extremely high .
Since the majority of the energy youre consuming during a fat fast originates from fats, your body initiates lipolysis and begins utilizing fat stores for energy.
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Isnt Fasting The Same As Reducing Calories
No, not necessarily. Fasting can reduce the time you spend eating and primarily addresses the question of when to eat.62 Calorie reduction addresses the question of what and how much to eat. They are separate issues and should not be confused with each other.
Try The Most Popular/effective Method
The most popular method is 16/8. Otherwise known as the timed restricted eating routine. This involves 16 hours of fasting and 8 hours of eating. During the eating window you should consume balanced keto meals. Either 2 large meals or 3 smaller meals. Avoid snacking to maximise results and to maintain a strong digestive system. Overeating can cause your digestive system and your metabolism to slow down. This can cause stomach issues and weight gain.
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What Is An Egg Fast
An egg fast is a short-term diet plan that involves eating eggs in the day with cheese and butter, and it was developed by blogger Jimmy Moore back in 2010.
Its a restricted version of the ketogenic diet, so it is also high in fat, moderate in protein intake, and super low in carbs. You can eat eggs on keto, along with the full-fat dairy, too.
Why choose an egg fast? It is supposed to help you get through stagnation when youre looking to lose weight and have hit a plateau. Some people may also use it to help their body enter into ketosis for a traditional keto diet. How many eggs do you eat a day? You need to have at least 6 whole eggs, but can have more . You are slashing calorie intake though, regardless, so that is also supposed to aid in weight loss from a 3 day egg fast or 5 day egg fast. You are likely not going to go more than 5 days, as it is a very restrictive diet.
Intermittent Fasting And Muscle
Two ground-breaking studies have recently been published on the effects of intermittent fasting on males. One group of researchers studied the effects that 16 hours of intermittent fasting had on males that lift weights. They found that muscle mass stayed the same, fat mass decreased significantly, and the males who fasted for 16 hours a day burned more fat for fuel compared to the control group that only fasted for 12 hours.
Another study showed that combining 20 hours of fasting with resistance training resulted in an increase in muscle mass, strength, and endurance, and this was achieved by eating ~650 calories per day less than normal.
The benefits of intermittent fasting translate to untrained overweight and obese individuals as well. One study published in Obesity Reviews found that eating fewer calories is effective for fat loss, but it does come with some muscle loss. However, if the subjects fasted for 24 hours and ate as much as they wanted on the next day for a period of 12 weeks, they lost significantly less muscle mass.
Yes you read that correctly 24 hours of intermittent fasting without any resistance training and these subjects were able to preserve more muscle mass than the subjects that ate fewer calories every day without fasting at all. This finding contradicts our common sense, but when we dig deeper into autophagy we can find the mechanism behind this result.
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Intermittent Fasting Why Meal Timing Matters
Simply put, intermittent fasting is the dietary strategy of restricting your food consumption to a specific window of time. For example, one of the most common intermittent fasting approaches is fasting during an 18-hour window of time and eating during the 6-hour window of time that is left in the day.
Lets say your last meal was at 6 pm last night and you ate nothing else after that. To implement an intermittent fast, simply restrict eating until 12 pm the next afternoon . To do this every day, only eat between 12 pm and 6 pm and fast for the remainder of the day.
There are many different variations of intermittent fasting as well. Dr. Dom DAgostino, a well-known ketogenic diet researcher, suggests doing a longer intermittent fast for 3 days, 3 times a year. This means not eating for 3 days, and eating normally until the next fast.
Another way to try fasting for yourself is by incorporating intermittent fasts of 16 or more hours per day into your lifestyle. This is a much more accessible strategy that allows you to experience many of the benefits of taking a short break from calories.
Despite the simplicity of this concept, it may not be readily apparent how beneficial intermittent fasting can be for you, especially if you are already benefiting from the ketogenic diet.
How Does Fat Fasting Help You Burn Fat
Now we know that the main calories of fat fasting diet come from fats in food. It works to create the ketone molecules in the body that mainly results from the fats in the food that we eat. This diet promotes the breakage of fatty acids in the liver into ketone molecules.
As we said, fat fast is very low in calories and high in fat. Its designed to quickly decrease the carb stores and create a calorie deficit. If you adhere to fat fasting for 2-5 days, you may begin burning fat as your primary source of fuel due to entering ketosis. Especially if you are already on a low-carb diet because, in that case, a fat fast may also boost your ketone levels. Therefore, you lose weight because of the calorie deficit itself, but also by moving your body into ketosis and burning more fat.
Nevertheless, huge weight loss cant be explained by fat loss alone as a fat fast only lasts a few days. The reason for large shifts on the scale is because of a loss of water.
Water is stored alongside glycogen, the stored form of glucose, so when you lose glycogen you also lose water. In fact, if youre not already keto-adapted or youre doing a fat fast after a cheat day, you may think that you lost fat, but a lot of the weight lost during a fat fast is likely water weight.
In conclusion, as soon as you begin eating carbs again and replace your bodys glycogen stores, the weight will return.
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Intermittent Fasting And Keto: The Takeaway
As ways of eating inspired by ancestral eating patterns, intermittent fasting and keto are two sides of the dietary coin.
Intermittent fasting speeds up metabolism, while keto switches your body into metabolizing its excess fat stores.
Intermittent fasting activates cellular spring cleaning and renewal, while keto eliminates the sugar that can damage cells while feeding new cells with energy packed ketones.
These complementary forces enhance many of the shared benefits of intermittent fasting and keto including increased weight loss, reduced risk of diseases, reduced inflammation.
For women combining IF and keto can be particularly important by protecting against hormone imbalances that can be triggered by hypoglycemic stress. As always, these benefits depend on a well-formulated approach centered on healthy whole foods. We recommend building your intermittent fasting and keto meal plan around whole animal-based foods, keto specific superfoods, and exploring organ meats.