When following a ketogenic diet, limiting your carb intake is essential for achieving and maintaining ketosis. Ketosis occurs when your body switches from primarily burning glucose to burning fatty acids and ketones for fuel. This metabolic state has been shown to aid weight loss, lower blood sugar, and provide other health benefits.
But how low do you need to go with your carb intake to reach ketosis? The answer depends on several factors.
What are net carbs?
To understand how many carbs you need for ketosis, it’s important to distinguish between total carbs and net carbs. Net carbs are calculated by subtracting the grams of fiber from the total carbohydrates in a food or meal.
Fiber does not impact blood sugar or ketone levels in the same way that digestible carbs do. That’s because fiber is not fully broken down and absorbed. For that reason, most ketogenic dieters focus on limiting net carbs specifically.
Standard ketogenic diet net carb intake
The standard ketogenic diet (SKD) typically recommends limiting net carbs to 20-50 grams per day. This level allows most people to reach and sustain ketosis.
Here are some examples of the amount of net carbs in common ketogenic diet foods:
| Food | Net carbs |
|---|---|
| 1/2 cup blueberries | 7 grams |
| 1 ounce almonds | 2.5 grams |
| 1 cup raw spinach | 0.5 grams |
| 3 ounces salmon | 0 grams |
As you can see, non-starchy vegetables, nuts, seeds, fish, meat, eggs and healthy oils are all low in net carbs. By building your meals around these foods and keeping servings of higher carb foods small, it’s possible to stay under 50 net grams daily.
Individual carb needs
While 20-50 net grams is the general recommendation, some individuals may need to go even lower or can get away with going slightly higher.
Factors that affect carb needs for ketosis include:
- Metabolic health – Insulin resistant individuals may need to go lower.
- Physical activity level – Active individuals may be able to eat more carbs.
- Body size – Larger bodies often require lower carb intake.
- Carb tolerance – Some people can eat more carbs and stay in ketosis.
The best way to determine your personal carb limit for ketosis is to test your ketone levels. Blood ketone meters provide the most accurate measurements. Aim for a ketone level between 0.5-3.0 mmol/L to confirm you are in nutritional ketosis.
Very low-carb ketogenic diets
Some variations of the ketogenic diet focus on carb counts that are even lower than the standard SKD range. These include:
Cyclical ketogenic diet
The cyclical ketogenic diet (CKD) involves periods of very low carb intake, such as less than 20 net grams per day for 5-6 days straight. This is followed by 1-2 days of higher carb intake, around 150 grams.
The purpose of the high-carb days is to replenish glycogen stores for intense workouts. This diet is often used by athletes and bodybuilders.
Targeted ketogenic diet
The targeted ketogenic diet (TKD) allows for 20-50 grams of carbs around workouts. Otherwise, daily carb intake remains very low, around 20-30 net grams.
The purpose of targeting carbs around workouts is to provide glucose when it is needed for high-intensity exercise performance.
Keto net carb counting tips
Here are some tips for tracking and limiting net carbs on a ketogenic diet:
- Use an app to look up the net carbs in foods easily.
- Read nutrition labels carefully and subtract fiber from total carbs.
- Stick to whole, unprocessed foods as often as possible.
- Watch portions of foods like nuts, dairy and some low carb fruits.
- Focus meals around protein, healthy fats and low-carb vegetables.
- Skip grains, sugar, starchy vegetables and most fruits.
Should you count total carbs or net carbs?
In most cases, tracking net carbs rather than total carbs makes the most sense for a true ketogenic diet. The reason is that fiber does not impact ketosis like other carbohydrates.
However, some experts suggest that both types of fiber should not necessarily be fully excluded from carb counts. While some fibers like cellulose are non-digestible, other fibers can be partially broken down and may need to be limited on very low-carb diets.
Additionally, some people aim for ultra-low carb diets below 20 total grams (not just net grams) for therapeutic uses of the ketogenic diet, like managing epilepsy. In those cases, total carbs may be tracked instead.
As long as you’re tracking one or the other accurately and making adjustments based on ketone testing, counting net carbs or total carbs can both be effective strategies.
Should carbs be limited at certain times?
In addition to keeping daily carb intake low, some research suggests there may be benefits to reducing carb consumption at specific times of day – especially in the evening and at night.
Animal studies have found that mice who consume carbs only during their active period gain less fat than mice who eat carbs day and night. The mice naturally consume more carbs during their awake hours.
This may be because carbs consumed at night when you’re inactive are more likely to be stored as fat. Carb timing could potentially boost fat loss.
Additionally, some evidence suggests your body may be more efficient at processing and utilizing carbs during the daytime. So you may be able to consume slightly more carbs earlier in the day without disrupting ketosis.
However, more human research is needed to say for sure whether carb timing makes a significant difference or not.
How to tell if you’re in ketosis
Since individual responses vary, it’s important to monitor and adjust your carb intake to ensure you reach and stay in ketosis. Signs you may be in ketosis include:
- Weight loss
- Reduced hunger and appetite
- Elevated ketone levels
- Improved mental focus
- Heightened energy and endurance
Testing your blood or urine ketone levels provides objective data to confirm you’ve reached ketosis. This allows you to adjust your diet until you find your optimal carb limit for maintaining the metabolic state on an ongoing basis.
Potential benefits of ketosis
Reaching and maintaining nutritional ketosis generally requires restricting net carb intake to somewhere below 50 grams per day at a minimum. But this dietary change can provide many benefits, including:
- Enhanced weight loss, especially reducing belly fat
- Better blood sugar control and insulin sensitivity
- Improvements in markers of metabolic syndrome
- Reduced inflammation markers
- Increased HDL (good) cholesterol
- Improved mental clarity and focus
Ketosis may also be therapeutic and improve conditions like epilepsy, Alzheimer’s disease, Parkinson’s disease, PCOS, and some cancers. More research is underway.
Potential side effects
Transitioning to a very low-carb diet can sometimes cause side effects often referred to as “keto flu.” Symptoms may include:
- Headaches
- Dizziness and fatigue
- Hunger and cravings
- Trouble sleeping
- Nausea
- GI issues
- Poor exercise performance
- Brain fog and trouble concentrating
These effects usually subside within 1-2 weeks as your body adapts to burning fat instead of glucose for fuel. Staying well hydrated and getting enough sleep, salt, magnesium and potassium can help counteract these temporary effects.
Maintaining ketosis long-term
Reaching ketosis by restricting carbs requires some initial adaptation. But staying in consistent nutritional ketosis long-term requires establishing new dietary habits to keep your carb intake around 20-50 grams or less per day.
Tips for maintaining ketosis include:
- Meal planning and tracking macros
- Finding keto-friendly recipes
- Avoiding carb-heavy foods like bread, pasta, baked goods, starchy veggies, and sweets
- Dining out smart – opting for bunless burgers, salads, and switching out fries for veggies
- Reading labels carefully
- Finding suitable low-carb substitutes for higher carb foods you miss
Conclusion
Limiting net carbs to 20-50 grams per day can help most people achieve ketosis within a short period of time. However, some individuals may need to go lower or can get away with going slightly higher based on personal tolerance and other factors.
Testing ketones and staying under your daily carb limit consistently is key for maintaining the benefits of ketosis in the long run. While very low-carb diets take some adjustment initially, this style of eating can improve many aspects of health.