Intermittent fasting and low-carb diets share crucial goals and benefits. They put you into ketosis, help burn fat, and lower blood sugar and insulin.
Do health benefits and results multiply when you combine low-carb and intermittent fasting? I researched for you. Save time and find all the answers in this science-backed article.
What Is Intermittent Fasting?
During intermittent fasting (IF), you eat within a specific time window and fast during the rest of the day.
While several intermittent fasting forms exist, eating within about 8 hours is the most popular.
Therefore, as with the classic 16/8 intermittent fasting protocol, 16 hours of the day are determined to be fasting. Sleep also 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
Can You Do Low-Carb and Intermittent Fasting?
Both approaches have a significant common benefit: They lower the storage hormone insulin.
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 However, studies show that the outdated approach leads to weight gain in the long term (Fothergill et al. 20165).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% 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.
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.
Developed in the 1960s, the Atkins diet is the classic low-carbohydrate diet.
But this is precisely where its weaknesses lie. Since nobody knew that protein strongly stimulates insulin until the 1990s, people started replacing 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.
Above all, lean protein can lead to solid insulin reactions without the protective effect of fat. Unfortunately, due to fat’s medical demonization, we have begun to remove fats from natural foods.
The Atkins approach was doomed to fail since restricting protein and consuming healthy fats is far more effective in weight loss.
On the other hand, the keto diet also considers that proteins stimulate insulin.
In this sense, keto and intermittent fasting also have the common goal of lowering insulin levels, depleting carbohydrate stores, and burning fat for energy.
And the term ketosis refers to the body’s natural ability to burn fat for energy.
Since the body spreads this fat energy through so-called ketones, the state of fat burning is called ketosis.
A low insulin level is essential because insulin blocks the enzyme that breaks down body fat (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 and Low-Carb Benefits
Intermittent fasting and low-carb diets aim at common goals. But what does the science say?
Which approach gets you better results, and do benefits multiply when combined?
1. Blood Sugar Regulation
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%.
This may not be surprising since fasting is also a zero-carb approach, free of other macronutrients, such as protein and fat.
The glucose response is significantly smaller if we compare the low-carb diet with the standard western diet. However, fasting is still better.
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, one can sustainably reduce blood sugar levels with the proper diet, which has nothing to do with calorie requirements.
Nevertheless, fasting is still somewhat more effective. If a zero-carb approach does not achieve the desired effect, one cannot become even more carbohydrate-free or ketogenic.
When fasting, you can still go one step beyond and fast one more hour or even a day.
Since the world record for fasting is 382 days, there is plenty of room (Stewart et al. 197312).
Furthermore, blood sugar is more stable when fasting than on a standard western diet since the liver produces glucose from fat and protein (gluconeogenesis). Also, there cannot be a blood sugar crash without an initial blood sugar spike.
2. Diabetes Prevention
Type 2 diabetes and its pre-existing disease, insulin resistance characterized by too much sugar and too much insulin (hyperinsulinemia) in the body.
Therefore, reducing the intake of refined carbohydrates and sugar in the diet is essential.
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, a 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, combining low-carb with intermittent fasting also makes sense. Sticking to a standard diet during eating will drive up blood sugar and insulin levels and minimize fasting benefits.
With this in mind, too much insulin is not the only 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 excess 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 carbohydrate reduction reduces insulin.
Therefore, it is no secret that low-carb diets can reduce weight, especially abdominal fat (Volek et al. 200415).
Since protein also increases insulin levels, reducing protein and increasing healthy fats in the diet makes sense. 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 the 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 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
4. Lean Mass
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 in 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 using 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 also learn to exploit it.
Since intermittent fasting stimulates the growth hormone, it can help build lean mass (Ho et al. 198818).
The Bottom Line
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.
Compared to low-carb, intermittent fasting 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.
Those who do not change their diet habits won’t experience noticeable weight loss or mental health improvements with intermittent fasting.
Frequently Asked Questions (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 aims to burn 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 effectively you can burn body fat and lose weight.
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Stephan is a writer and a true man of science, holding multiple diplomas and master's degrees in different research areas. His greatest passion is closing the gap between the conventional perception of health and the latest scientific evidence – always following the data.