How low carb is low carb?
Low carb is often defined as any diet containing fewer than 130 grams of carbs per day. Generally speaking, the fewer the carbs, the more effective the diet appears to be for weight loss without hunger and for treating type 2 diabetes.1 However, eating fewer carbs also makes the diet more restrictive and can make it feel more challenging to sustain.
At Diet Doctor, we recommend recipes and meal plans for up to 100 grams of carbs per day. Here are three examples of how a low-carb dinner can look, depending on how many carbs you eat per day (the yellow stuff is delicious herb butter).
Under 20 grams per day
20-50 grams per day
50-100 grams per day
Here’s the way we define different levels of carb intake at Diet Doctor:
- Ketogenic low carb <20 grams of net carbs per day.2This level of carbohydrates is defined as below 5 energy percent (E%) carbs in our recipes or, if it is a meal, 7 grams of carbs or less.3 In our ketogenic recipes, the amount of carbs per serving is shown in green balls.
- Moderate low carb 20-50 net grams per day. This level is defined as between 5-10 E% carbs in our recipes and the amount of carbs per serving is shown in yellow balls.
- Liberal low carb 50-100 net grams per day. This means 10-20 E% carbs in our recipes and the amount of carbs per serving is shown in orange balls.
For comparison, a regular Western diet can easily contain 250 grams of carbs or more in a day — most of them refined carbs, including sugar.4
Note: Although our recipes are arranged by percent calories from carbs, protein, and fat, we do not feel you need to calculate these on your own. We provide them as a reference, but we recommend you limit your carbs, ensure adequate protein, and adjust fat as needed for taste. That eliminates the need to constantly calculate “percent macros.”
Our listed carb counts are the number of digestible carbs, also called net carbs. This simply means we do not count the fiber.5 For example, you can eat nearly all the fiber you want from keto vegetables without seeing a significant blood sugar or insulin impact.6
However, don’t be fooled by the label “net carbs” on processed products, like chocolate bars. The labels can be misleading, as these products are often full of sugar alcohols that can have potential negative effects on weight and blood sugar.7 If in doubt, avoid anything with the words “net carbs” printed on it.
An effective low-carb diet is ideally based on fresh, unprocessed food.8 Learn more
How to choose
Some people may need to keep the carbs very low for maximum effect – a keto low-carb diet. This includes many people with significant weight issues, diabetes (mainly type 2) and food or sugar addiction, for example.9
Other, more carb-tolerant people, may do very well on a liberal low-carb diet.10 This also lowers the risk of any side effects.
The third group – healthy, lean, active people – may not even need to eat very low carb, as long as they consume mainly unprocessed carbs.
We believe that people looking for dramatic health improvements may do best starting out on a strict keto diet.11 Later, as you hopefully approach your weight and health goals, you can try adding back some carbs and see if you can maintain your health gains.
However, if avoiding most carbs does not feel possible to you, it’s possible to obtain health benefits just by avoiding the worst carbs.12 Feel free to use the guide below for a more gradual start:
Low-carb basics videos
How low carb is low carb? - the evidence
The guide contains scientific references. You can find these in the notes throughout the text, and click the links to read the peer-reviewed scientific papers. When appropriate we include a grading of the strength of the evidence, with a link to our policy on this. Our evidence-based guides are updated at least once per year to reflect and reference the latest science on the topic.
All our evidence-based health guides are written or reviewed by medical doctors who are experts on the topic. To stay unbiased we show no ads, sell no physical products, and take no money from the industry. We're fully funded by the people, via an optional membership. Most information at Diet Doctor is free forever.
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This is mainly based on the consistent experience of low-carb practitioners and stories from people trying different levels of carb restriction. [weak evidence]
The only small intervention study – to our knowledge – that compared different levels of carb restriction found trends toward greater weight loss and improvements in cardiometabolic risk factors as carb intake went lower. However, these trends did not reach statistical significance:
Low-carb diets can reduce hunger:
Low-carb diets can help reduce or even normalize blood sugar in people with type 2 diabetes:
A non-randomized trial with risk of financial bias shows that a very low-carb diet is remarkably effective at treating type 2 diabetes:
Net carbs = digestible carbs, i.e. total carbs minus fiber. ↩
The limit of five percent energy means that, if eating 2000 calories/day, five percent (or less) of your calorie intake will come from carbs. In practical terms, this means you’ll stay below a maximum of 20 grams of carbs on a 2,000-calorie diet, even if you only choose our most carb-rich keto recipes. In most cases, you’ll end up with far fewer carbs than that, as some of the keto recipes you use are likely to have significantly less than the maximum amount of carbs. ↩
Adults in the US consume about 50% of their calories from carbohydrates, or about 250 grams of carbs per day if eating 2000 calories:
Although some low-carb experts disagree, it’s generally accepted that humans lack the enzymes needed to break down fiber and absorb it into the bloodstream. Therefore, the fiber portion of carbs typically does not raise blood sugar or insulin levels.
Fiber does not directly affect blood sugar levels, though it can indirectly slow down the absorption of digestible carbohydrates that you eat.
Fiber can have both beneficial and some potential negative effects on gut health, but it usually has no major impact on the effects of a low-carb diet. ↩
For example, maltitol – a very common sweetener in low-carb products – has the highest glycemic (35) and insulinemic (27) indexes of all sugar alcohols.
About 50% of maltitol is digested and absorbed in the small intestine, like other carbs.
Gastroentérologie Clinique et Biologique 1991: Clinical tolerance, intestinal absorption, and energy value of four sugar alcohols taken on an empty stomach [randomized controlled trial; moderate evidence]
This is mainly based on evolutionary theories and clinical experience. [weak evidence]
Focus on eating good quality, minimally processed real food. Ideally, the food you buy shouldn’t even have a list of ingredients (or it should be very short).
Unprocessed real food is what our ancestors have been eating for millions of years, and what the human animal is evolutionarily adapted to. By introducing processing, e.g. refining carbohydrates in a way that increases the speed of absorption and reduces the amount of nutrients and fiber, we change the food into something to which our bodies may not be adapted, increasing the risk of adverse health effects.
This is mainly based on the consistent experience of low-carb practitioners, and stories from people trying different levels of carb restriction. [weak evidence]
The only small intervention study – to our knowledge – that compared different levels of carb restriction found trends toward larger effects with fewer carbs, on weight loss and cardiometabolic risk factors. However, these trends did not reach statistical significance:
Regarding sugar/food addiction, this can be improved by avoiding the high-reward foods that stimulate cravings, most of which are processed foods full of sugar and/or other refined carbohydrates. [clinical experience, weak evidence]
Keto diets have also been shown to reduce hunger:
Unless there’s a specific reason for you not to do this.
Whether people go on a low-carb or a low-fat diet, they tend to lose weight as long as they minimize sugar and refined flours in their diet:
JAMA 2018: Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion [randomized controlled trial; moderate evidence]
Read more about the above study in our analysis.
Here are more studies and overview articles showing a connection between sugar, excess weight and disease:
The American Journal of Clinical Nutrition 2007: Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease [overview article; ungraded]