Intermittent fasting and low-carb diets have goals and effects in common: Both lower blood sugar and insulin, and both put you in ketosis and help burn fat.
Low-carb vs. intermittent fasting: Which is Better? Are there specific scenarios in which an intermittent fasting plan outperforms a low-carb diet and vice versa?
How Does Intermittent Fasting Work?
During intermittent fasting (IF), you eat within a specific time window and fast during the rest of the day.
While there are several intermittent fasting forms, the most popular is eating within a time window of about 8 hours.
Therefore, as with the classic 16/8 intermittent fasting protocol, 16 hours of the day are determined to fasting. Sensibly also the sleep falls into this period, whereby only 8 hours of fasting remain.
Since there are straightforward rules, it’s simple to start with intermittent fasting:
- Skip breakfast
- No snacks
- Water, tea, coffee without milk and all sweeteners
Low Carb and Intermittent Fasting
What is the difference between intermittent fasting vs. low carb?
Both dietetic approaches have a common goal: They want to lower the storage hormone insulin.
And this is not only target-oriented in terms of weight loss but also reduces the risk of the major diseases and causes of death in our western world, such as (Herman et al. 20171; Orgel et al. 20142; Ferreira et al. 20183; Athauda et al. 20164):
- Insulin Resistance
- Metabolic syndrome
- Type 2 diabetes
- Cardiovascular diseases
For decades, we have worked under the false assumption that only excessive calories cause weight gain.
Calorie restriction can lead to short-term weight loss. However, studies show that the outdated approach leads to weight gain in the long term (Fothergill et al. 20165).
Accordingly, a study of 76,704 obese men and 99,791 obese women showed that an incredible 99.5% of them could not successfully lose weight with calorie reduction (Flides et al. 20156).
Accordingly, obesity is not a caloric but a hormonal imbalance.
Conversely, when insulin levels fall, people lose weight.
Let’s look at type 1 diabetes – a fatal disease before insulin was discovered. Why?
Because the beta cells in the pancreas could no longer produce insulin, the storage hormone’s absence led to weight loss until the affected person died.
Atkins and Intermittent Fasting
The Atkins diet, which was developed in the 1960s, is the classic low-carbohydrate diet par excellence.
But this is precisely where its weaknesses lie. Since nobody knew that protein also strongly stimulates insulin until the 1990s, people started to replace carbohydrates with lean protein (Nuttall et al. 19919).
For this reason, classic low-carbohydrate diets such as the Atkins diet are not nearly as effective at losing weight as intermittent fasting.
In contrast, pure fats such as extra virgin olive oil cause virtually no insulin response at all.
Above all, lean protein can lead to strong insulin reactions without the protective effect of fat. Unfortunately, due to fat’s medial demonization, we have begun to remove fats from natural foods.
Since it is far more effective in terms of health and weight loss to restrict protein and consume healthy fats, the Atkins approach was doomed to fail.
Keto and Intermittent Fasting
On the other hand, the keto diet considers that proteins stimulate insulin as well.
In this sense, keto and intermittent fasting also have the common goal of lowering insulin levels, deplete carbohydrate stores, and burn fat for energy.
And the term ketosis refers to nothing else than the body’s natural ability to burn fat for energy.
Since the body spreads this fat energy in the form of so-called ketones, the state of fat burning is called ketosis.
Because insulin blocks the enzyme that breaks down body fat, a low insulin level is essential once again (Meijssen et al. 200110).
Therefore fasting is the easiest and fastest way to get into ketosis.
Because the low-carb high-fat (LCHF) diet aims at the same effects as fasting, you can combine intermittent fasting and keto very well.
Intermittent Fasting vs. Low Carb
But which is better: low-carb or intermittent fasting?
The scientific comparison shows the differences concerning the essential aspects of these methods with common goals:
1. Blood Sugar
While eliminating carbohydrates ensures a lack of fuel to raise blood sugar and insulin levels, fasting can go one step beyond.
Accordingly, a study comparing fasting and low-carb in type-2-diabetics shows that zero-carb nutrition has tremendous impacts.
Nevertheless, fasting can be more consequential.
While the LCHF approach lowered blood sugar by 35% compared to the standard American diet (SAD), fasting reduced blood sugar by about 50%.
Since fasting is also a zero-carb approach, which is also free of the other macronutrients, such as protein and fat, this may not be surprising.
If we compare the low-carb diet with the standard western diet, the glucose response is significantly smaller. However, fasting is still better off.
Nevertheless, eliminating carbohydrates without calorie restriction could still account for 71% of the positive effect fasting had on blood sugar.
Researchers gave both diets (LCHF and SAD) to the patients in 3 meals per day.
Since the LCHF diet also consisted of 1750 calories, it was not a calorie restriction that caused blood sugar levels to drop (Nuttall et al. 201511).
According to this, with the right diet, which has nothing to do with calorie requirements, one can reduce blood sugar levels sustainably.
Nevertheless, fasting is still somewhat more effective. If a zero-carb approach does not bring the desired effect, one cannot become even more carbohydrate-free or more ketogenic.
When fasting, you can still go one step beyond and fast one more hour or even day.
Since the world record in fasting is 382 days, there is plenty of room (Stewart et al. 197312).
Furthermore, blood sugar is more stable when fasting than when eating a standard western diet since the liver produces glucose from fat and protein (gluconeogenesis). Also, without an initial blood sugar spike, there cannot be a blood sugar crash.
2. Insulin Resistance and Diabetes
Type 2 diabetes and its pre-existing disease insulin resistance characterize too much sugar and too much insulin (hyperinsulinemia) in the body.
Therefore, it is essential to cut down the intake of refined carbohydrates and sugar in the diet.
Accordingly, low-carb and intermittent fasting fulfill this essential point by minimizing carbohydrates.
Therefore, our study’s diabetes patients could reduce their insulin levels by 48% with low-carb and 69% with fasting.
Since a low-carb diet still contains proteins that increase insulin levels, the weaker outcome is plausible.
On average, the insulin response to carbohydrate elimination was less than one-third of a conventional diet (Nuttall et al. 201513).
For this reason, it also makes sense to combine low-carb with intermittent fasting. If you stick to a standard diet during eating periods, this will drive up blood sugar and insulin levels and minimize fasting benefits.
With this in mind, too much insulin is not the only but the primary driver of obesity and type 2 diabetes.
While diets hardly can, intermittent fasting can burn visceral fat in the liver and reverse insulin resistance and type 2 diabetes naturally (Halberg et al. 200514).
As it fights off these diseases’ root causes, intermittent fasting is more effective than a low-carb diet.
3. Weight Loss
Since the excess of insulin leads to weight gain, both low-carb and intermittent fasting are practical approaches to weight loss.
It’s not about calories. Refined carbohydrates are the most significant insulin stimulus, so a carbohydrate reduction reduces insulin.
Therefore, it has long been no secret that low-carb diets can reduce weight, especially abdominal fat (Volek et al. 200415).
Since protein also increases insulin levels, it makes sense to reduce protein and increase healthy fats in the diet in return. The bottom line is a ketogenic diet:
- 75-80% fat
- 20-25% protein
- 5-10% carbohydrates
Eating 100% pure fat, which hardly stimulates insulin, is challenging.
One of the few possibilities is a so-called Bulletproof Coffee, which enjoys worldwide popularity due to its energy boost from 100% fat.
However, fasting is the most effective way to lower insulin levels and lose weight. And you can always fast longer.
Accordingly, fasting is the ultimate ketogenic diet, so to speak, since you live 100% on fat – your body fat.
Therefore, intermittent fasting can burn harmful fat better than low-carb diets (Catenacci et al. 201616).
Since you can always go one step beyond when fasting, you will be ahead when losing weight. Nevertheless, the combination of intermittent fasting and low-carb is the most effective way to lose weight:
- Less insulin
- More fat burning
- Fewer health risks
Especially endurance athletes who want to maximize their aerobic performance often struggle with extreme carbohydrate restriction.
However, they can train on a low-carb diet while supplementing their energy intake with carbohydrates on competitions.
Many athletes call this combination the best of both worlds – low-carb and high-carb.
However, since low-carb nutrition predominates during training, the body is trained to burn stored body fat more efficiently.
For this reason, athletes can tap into body fat for as long as possible, even during a competition, and still have carbohydrates in their glycogen stores when others are running low.
On the other hand, many strength athletes do not want to do without carbohydrates altogether. Since they frequently empty their glycogen stores, they want to use dietary carbohydrates for muscle recovery (Murray et al. 201817).
With this in mind, combining low-carb and intermittent fasting can turn out great when applied correctly:
- Training day: More carbohydrates that can directly refill the glycogen stores of the muscles
- Rest day: carbohydrate-free LCHF or ketogenic diet
- Intermittent fasting: 16/8 with exercise at the end of the 16 hours before eating
However, you can modify any low-carb diet to athletic needs utilizing carb-cycling or a cyclical ketogenic diet.
Both low-carb and intermittent fasting can thus bring legitimate benefits for sports. Nevertheless, fasting stands out again, so bodybuilders learned to exploit it as well.
Since intermittent fasting stimulates the growth hormone, it can help build up lean mass (Ho et al. 198818).
Combine Low Carb and Intermittent Fasting to Get Results!
Intermittent fasting and low carb are essential for health and weight loss.
While low carb shuts down the cause of weight gain and modern diseases, intermittent fasting is the maintenance service that can repair the damage done.
When comparing low carb vs. intermittent fasting, the latter is more effective with blood sugar, insulin, and fat loss. However, it won’t do the work without diet support.
Because the more we eat industrially processed carbohydrate junk, the more we have to fast. If we continuously consume fast food, protein bars, and bakery goods, which let insulin soar, 16 hours of intermittent fasting is not enough.
Accordingly, a carbohydrate-based diet prevents intermittent fasting benefits, such as improved fat burning or memory function.
Moreover, frequent carb-loading inhibits the benefits of fasting and causes side effects such as keto flu and cravings.
Who does not change diet habits won’t experience noticeable weight loss or mental health improvements with intermittent fasting.
Since you are already on your way to ketosis and autophagy, the combination of intermittent fasting and keto is most effective in my experience.
Intermittent Fasting vs. Low Carb FAQ
Is Intermittent Fasting better than low carb?
Although intermittent fasting can be more potent than low-carb, it doesn’t work well with a high-carb diet. Hence, combining intermittent fasting with low-carb is the most powerful option.
Does intermittent fasting work with low carb diet?
Intermittent fasting works exceptionally well with low carb diets, since both aim on burning body fat for energy.
Does Calories matter when intermittent fasting?
Intermittent fasting aims at depleting your carbohydrate stores to burn body fat for energy. Therefore, calories matter less than carbohydrates in your diet.
How many carbs should I eat while intermittent fasting?
That’s up to you – the less you eat, the more effective you can burn body fat and lose weight.
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